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1.  The impact of arm position and pulse pressure on the validation of a wrist-cuff blood pressure measurement device in a high risk population 
Despite the increasing popularity of blood pressure (BP) wrist monitors for self-BP measurement at home, device validation and the effect of arm position remains an issue. This study focused on the validation of the Omron HEM-609 wrist BP device, including an evaluation of the impact of arm position and pulse pressure on BP measurement validation. Fifty patients at high risk for cardiovascular disease were selected (age 65 ± 10 years). Each patient had two measurements with a mercury sphygmomanometer and three measurements with the wrist BP device (wrist at the heart level while the horizontal arm supported [HORIZONTAL], hand supported on the opposite shoulder [SHOULDER], and elbow placed on a desk [DESK]), in random order. The achieved systolic BP (SBP) and diastolic BP (DBP) wrist-cuff readings were compared to the mercury device and the frequencies of the readings within 5, 10, and 15 mmHg of the gold standard were computed and compared with the British Hypertension Society (BHS) and Association for the Advancement of Medical Instrumentation (AAMI) protocols. The results showed while SBP readings with HORIZONTAL and SHOULDER positions were significantly different from the mercury device (mean difference = 7.1 and 13.3 mmHg, respectively; P < 0.05), the DESK position created the closest reading to mercury (mean difference = 3.8, P > 0.1). Approximately 71% of SBP readings with the DESK position were within ±10 mmHg, whereas it was 62.5% and 34% for HORIZONTAL and SHOULDER positions, respectively. Wrist DBP attained category D with BHS criteria with all three arm positions. Bland–Altman plots illustrated that the wrist monitor systematically underestimated SBP and DBP values. However a reading adjustment of 5 and 10 mmHg for SBP and DBP (DESK position) resulted in improvement with 75% and 77% of the readings being within 10 mmHg (grade B), respectively. AAMI criteria were not fulfilled due to heterogeneity. The findings also showed that the mismatch between the mercury and wrist-cuff systolic BP readings was directly associated with pulse pressure. In conclusion the DESK position produces the most accurate readings when compared to the mercury device. Although wrist BP measurement may underestimate BP measured compared to a mercury device, an adjustment by 5 and 10 mmHg for SBP and DBP, respectively, creates a valid result with the DESK position. Nevertheless, considering the observed variations and the possible impact of arterial stiffness, individual clinical validation is recommended.
PMCID: PMC2866552  PMID: 20463830
blood pressure; device validation; position
2.  Validation study of the Dinamap ProCare 200 upper arm blood pressure monitor in children and adolescents 
Korean Journal of Pediatrics  2011;54(11):463-469.
Purpose
To validate the Dinamap ProCare 200 blood pressure (BP) monitor against a mercury sphygmomanometer in children 7 to 18 years old in accordance with the 2010 International Protocol of European Society of Hypertension (ESH-IP2) and the British Hypertension Society (BHS) protocol.
Methods
Forty-five children were recruited for the study. A validation procedure was performed following the protocol based on the ESH-IP2 and BHS protocols for children and adolescents. Each subject underwent 7 sequential BP measurements alternatively with a mercury sphygmomanometer and the test device by trained nurses. The results were analyzed according to the validation criteria of ESH-IP2.
Results
The mean (±SD) difference in the absolute BP values between test device and mercury sphygmomanometer readings was 1.85±1.65 mmHg for systolic BP (SBP) and 4.41±3.53 mmHg for diastolic BP (DBP). These results fulfilled the Association for the Advancement of Medical Instrumentation criterion of a mean±SD below 5±8 mmHg for both SBP and DBP. The percentages of test device-observer mercury sphygmomanometer BP differences within 5, 10, and 15 mmHg were 96%, 100%, and 100% for SBP, and 69%, 92%, and 100% for DBP, respectively, in the part 1 analysis; both SBP and DBP passed the part 1 criteria. In the part 2 analysis, SBP passed the criteria but DBP failed.
Conclusion
Although the Dinamap ProCare 200 BP monitor failed an adapted ESH-IP2, SBP passed. When comparing BP readings measured by oscillometers and mercury sphygmomanometers, one has to consider the differences between them, particularly in DBP, because DBP can be underestimated.
doi:10.3345/kjp.2011.54.11.463
PMCID: PMC3254892  PMID: 22253643
Blood pressure; Oscillometric device; Dinamap; Validation studies; International protocol
3.  Validation of the Oregon Scientific BPU 330 for self-monitoring of blood pressure according to the International Protocol 
Vascular Health and Risk Management  2008;4(5):1121-1125.
Objective:
Extensive marketing of devices for self-measurement of blood pressure has created a need for purchasers to be able to satisfy themselves that such devices have been evaluated according to agreed criteria. The Oregon Scientific BPU 330 blood pressure monitor is an electronic device for upper arm measurement. This study assessed the accuracy of the Oregon Scientific BPU 330 blood pressure monitor according to the International Protocol by the Working Group on Blood Pressure Monitoring of the European Society of Hypertension for validation of blood pressure measuring devices.
Method:
52 participants over 30 years of age were studied in the validation. Nine blood pressure measurements were taken alternately with a mercury sphygmomanometer by two observers, and by the supervisor, using the BPU 330 device. A total of 33 participants were selected for the analysis. The validation was divided into two phases. Phase 1 included 15 participants. If the device passed phase 1, 18 more participants were included. The 99 pairs of measurements were compared according to the International Protocol. The device was given a pass/fail recommendation based on its accuracy compared with the mercury standard (within 5, 10, and 15 mmHg), as well as the number met in the ranges specified by the International Protocol.
Results:
The mean and standard deviation of the difference between the mean of the observers and the BPU 330 device were 1.7 ± 4.7 mmHg and 2.8 ± 3.9 mmHg for systolic blood pressure (SBP) and diastolic blood pressure (DBP), respectively. In phase 1, the device passed with a total of 33, 43, and 44 SBP readings; 38, 44, and 45 DBP readings were within 5, 10, and 15 mmHg, respectively. In phase 2.1, 81, 95, and 96 for SBP, and 83, 95, and 98 for DBP readings fell within the zones of 5, 10, and 15 mmHg, respectively. In phase 2.2, the last phase, 28 participants fell within the zone of two of the three comparisons, lying within 5 mmHg for SBP and 29 participants for DBP. No participants fell within the zone of all three of their comparisons over 5 mmHg apart for both SBP and DBP.
Conclusion:
The BPU 330 can be recommended for self-monitoring of blood pressure in the adult population, according to the International Protocol.
PMCID: PMC2605325  PMID: 19183762
blood pressure; self-monitoring; hypertension; International Protocol
4.  Evaluating the Accuracy of an Aneroid Sphygmomanometer in a Clinical Trial Setting 
American journal of hypertension  2008;22(3):263-266.
BACKGROUND
The mercury sphygmomanometer, the “gold” standard for blood pressure measurements, has been gradually phased out in many institutions because of environmental concerns. Our on-going clinical trial compared the use of mercury vs. aneroid sphygmomanometers, before implementing a study-wide transition to the aneroid sphygmomanometer.
METHODS
The Diabetes Prevention Program Outcomes Study (DPPOS) studied the accuracy of the Welch allyn Tycos 767-Series Mobile aneroid sphygmomanometer from 20 March 2006 to 21 June 2006 at multiple clinic centers. We compared readings from 997 participants in 24 clinic centers using both mercury and aneroid sphygmomanometers.
RESULTS
The study found no statistically significant difference for systolic blood pressure (SBP) (P > 0.05) and a small but significantly (P < 0.0001) lower (0.8 mm hg) reading for diastolic blood pressure (DBP) using the aneroid sphygmomanometer. Regression analysis of aneroid vs. mercury showed regression lines (Y = 4.8 + 0.96X for SBP, Y = 3.1 + 0.95X for DBP) slightly but statistically significantly different from the line of equality (P < 0.001). Participants’ age, sex, race/ethnicity, body mass index, blood pressure, and clinical center together explain about 8−10% of the variation of the difference between readings from the two sphygmomanometers. Based on the above result, on 1 august 2006, DPPOS clinics began the conversion from mercury to aneroid sphygmomanometers.
CONCLUSIONS
The Welch allyn Tycos 767-Series Mobile aneroid model 7670−04 tested in this validation study can be used to replace mercury model in clinical trials.
doi:10.1038/ajh.2008.338
PMCID: PMC2699679  PMID: 19057514
5.  Which is More Accurate in Measuring the Blood Pressure? A Digital or an Aneroid Sphygmomanometer 
Introduction
Hypertension is one of the major public health problem affecting the whole world so its accurate measurement is of utmost importance for its early diagnosis and management. Concerns related to the potential ill effects of mercury on health and environment, has led to the widespread use of non-mercury sphygmomanometers.
Aim
A study was conducted to compare the accuracy of readings of aneroid and digital sphygmomanometers in reference to mercury sphygmomanometers and determine the hypertensive classification agreement between the mercury and non-mercury devices.
Materials and Methods
The study was conducted in an OPD of a health centre in a rural community of West Bengal which is the rural field practice area of our institute. An aneroid and a digital sphygmomanometer were compared to a properly calibrated mercury sphygmomanometer. All the subjects above the age of 25 years, in two days per week, selected randomly from five working days per week in a period of one month were selected. Two blood pressure readings of each of 218 study subjects was recorded with each pretested sphygmomanometer. Paired t-test, Kappa coefficients, sensitivity and specificity tests were done. Receiver Operating Characteristics curve analysis was done and Youden index was estimated to detect the optimal cut off point for the diagnosis of hypertension by non-mercury sphygmomanometers.
Results
Data analysis of 218 study subjects showed the mean difference of the mercury reading and the test device was much less for aneroid than that of the digital device for both systolic and diastolic blood pressure. More than 89% of aneroid readings and less than 44% of the readings by digital device had absolute difference of 5mm Hg. when compared with the mercury readings for both systolic and diastolic blood pressure. Sensitivity and specificity of aneroid device was higher (86.7% and 98.7%) than digital device (80% and 67.7%). Receiver Operating Characteristic curve had larger area under the curve for aneroid device than digital device for both SBP and DBP.
Conclusion
The aneroid device had better accuracy than the digital device as compared to mercury sphygmomanometer and should be used for proper and better management.
doi:10.7860/JCDR/2016/14351.7458
PMCID: PMC4843288  PMID: 27134902
Blood pressure measurement; Digital sphygmomanometer; Hypertension; Receiver operating characteristics curve; youden index
6.  Validation of four automatic devices for self-measurement of blood pressure according to the International Protocol of the European Society of Hypertension 
Background
Four electronic devices for self-measurement of brachial blood pressure (BP): the Omron M1 Plus, the Omron M6 Comfort, the Spengler KP7500 D, and the Microlife BP A100 Plus, were evaluated in four separate studies according to the International Protocol of the European Society of Hypertension (ESH).
Design
The International Validation Protocol is divided into 2 phases: the first phase is performed on 15 selected subjects (45 pairs of BP measurements); if the device passes this phase, 18 supplementary subjects are included (54 pairs of BP measurements) making a total number of 33 subjects (99 pairs of BP measurements) on which the final validation is performed.
Methods
The same methodology recommended by the ESH protocol was applied for the 4 studies. In each study and for each subject, 4 BP measurements were performed simultaneously by 2 trained observers using mercury sphygmomanometers alternately with 3 measurements by the tested device. The difference between the BP value given by the device and that obtained by the two observers (mean of the two observers) was calculated for each measure. The 99 pairs of BP differences were classified into 3 categories (≤5, ≤10, ≤15 mmHg). The number of differences in each category was compared with the number required by the International Protocol. An individual analysis was then done to determine for each subject the number of comparisons ≤5 mmHg. At least 22 of the 33 subjects should have 2 of their 3 comparisons ≤5 mmHg.
Results
All 4 tested devices passed the first and the second phase of the validation process. The average differences between the device and mercury sphygmomanometer readings were −1.4 ± 5.5 and −0.4 ± 4.8 mmHg for SBP and DBP respectively for the Omron M1 Plus device, −2.1 ± 7.4 and 0.1 ± 4.9 mmHg for SBP and DBP respectively for the Omron M6 Comfort device, −1.4 ± 8.6 and −0.1 ± 3.5 mmHg for SBP and DBP respectively for the Spengler KP7500 D device, and 1.6 ± 4.2 mmHg and 0.54 ± 2.8 mmHg for SBP and DBP respectively for the Microlife BP A100 Plus device. For all devices, readings differing by less than 5, 10, and 15 mmHg for SBP and DBP values fulfill the recommendation criteria of the International Protocol as well as the individual analysis.
Conclusions
Omron M1 Plus (HEM-4011C-E), Omron M6 Comfort (HEM 7000-E), Spengler KP7500 D, and Microlife BP A100 Plus devices fulfilled the validation recommendations of the International Protocol.
PMCID: PMC2291343  PMID: 17969368
Omron M1 Plus (HEM-4011C-E); Omron M6 Comfort (HEM-7000-E); Spengler KP7500 D and Microlife BP A100 Plus; validation; International Protocol; self-blood pressure measurement
7.  Validation of the Omron HEM-7201 upper arm blood pressure monitor, for self-measurement in a high altitude environment, according to the European Society of Hypertension International Protocol revision 2010 
Journal of human hypertension  2013;27(8):487-491.
Few studies have been conducted on blood pressure monitors and their use at high altitude. This study is the first to evaluate an automated blood pressure device at high altitude following a standard validation protocol. The Omron HEM-7201 upper arm automatic blood pressure monitor was tested for accuracy in Lhasa, Tibet, China (3650 m above sea level) according to the European Society of Hypertension International Protocol revision 2010 (ESH-IP2). Thirty-three participants received 9–10 sequential blood pressure measurements alternating from a mercury sphygmomanometer and the device. The mean device-observer measurement difference was 1.0 ± 5.9 mmHg for systolic blood pressure (SBP) and −3.1 ± 4.6 mmHg for diastolic blood pressure (DBP). Of the 99 measurement pairs analyzed, 72, 90, and 97 device readings were within 5, 10, and 15 mmHg, respectively, of the observer measurements for SBP, and 68, 92, and 99 readings for DBP. The number of participants with at least two out of three measurements within 5mmHg was 27 for SBP and 25 for DBP. Three participants had no measurements within 5 mmHg for SBP or DBP. The Omron HEM-7201 passes the ESH-IP2 validation criteria and can therefore be recommended for use in adults in this setting.
doi:10.1038/jhh.2013.4
PMCID: PMC3709008  PMID: 23466876
blood pressure; high altitude; International Protocol; Tibet; validation studies
8.  An analysis of blood pressure measurement in a primary care hospital in Swaziland 
Abstract
Background
Measurement of blood pressure (BP) is done poorly because of both human and machine errors.
Aim
To assess the difference between BP recorded in a pragmatic way and that recorded using standard guidelines; to assess differences between wrist- and mercury sphygmomanometer-based readings; and to assess the impact on clinical decision-making.
Setting
Royal Swaziland Sugar Corporation Mhlume hospital, Swaziland.
Method
After obtaining consent, BP was measured in a pragmatic way by a nurse practitioner who made treatment decisions. Thereafter, patients had their BP re-assessed using standard guidelines by mercury (gold standard) and wrist sphygmomanometer.
Results
The prevalence of hypertension was 25%. The mean systolic BP was 143 mmHg (pragmatic) and 133 mmHg (standard) using a mercury sphygmomanometer; and 140 mmHg for standard BP assessed using wrist device. The mean diastolic BP was 90 mmHg, 87 mmHg and 91 mmHg for pragmatic, standard mercury and wrist, respectively. Bland Altman analyses showed that pragmatic and standard BP measurements were different and could not be interchanged clinically. Treatment decisions between those based on pragmatic BP and standard BP agreed in 83.3% of cases, whilst 16.7% of participants had their treatment outcomes misclassified. A total of 19.5% of patients were started erroneously on anti-hypertensive therapy based on pragmatic BP.
Conclusion
Clinicians need to revert to basic good clinical practice and measure BP more accurately in order to avoid unnecessary additional costs and morbidity associated with incorrect treatment resulting from disease misclassification. Contrary to existing research, wrist devices need to be used with caution.
doi:10.4102/phcfm.v6i1.590
PMCID: PMC4565038  PMID: 26245425
9.  The Relationship Between Preoperative and Primary Care Blood Pressure Among Veterans Presenting from Home for Surgery. Is There Evidence for Anesthesiologist-Initiated Blood Pressure Referral? 
Anesthesia and Analgesia  2011;114(1):205-214.
Background
American College of Cardiology/American Heart Association guidelines describe the perioperative evaluation as “a unique opportunity to identify patients with hypertension,” however factors such as anticipatory stress or medication noncompliance may induce a bias toward higher blood pressure, leaving clinicians unsure about how to interpret preoperative hypertension. Information describing the relationship between preoperative intake blood pressure and primary care measurements could help anesthesiologists make primary care referrals for improved blood pressure control in an evidence-based fashion. We hypothesized that the preoperative examination provides a useful basis for initiating primary care blood pressure referral.
Methods
We analyzed retrospective data on 2807 patients who arrived from home for surgery and who were subsequently evaluated within 6 months after surgery in the primary care center of the same institution. After descriptive analysis, we conducted multiple linear regression analysis to identify day-of-surgery (DOS) factors associated with subsequent primary care blood pressure. We calculated the sensitivity, specificity, and positive and negative predictive value of different blood pressure referral thresholds using both a single-measurement and a two-stage screen incorporating recent preoperative and DOS measurements for identifying patients with subsequently elevated primary care blood pressure.
Results
DOS systolic blood pressure (SBP) was higher than subsequent primary care SBP by a mean bias of 5.5mmHg (95% limits of agreement +43.8 to −32.8). DOS diastolic blood pressure (DBP) was higher than subsequent primary care DBP by a mean bias of 1.5mmHg (95% limits of agreement +13.0 to −10.0). Linear regression of DOS factors explained 19% of the variability in primary care SBP and 29% of the variability in DBP. Accounting for the observed bias, a two-stage SBP referral screen requiring preoperative clinic SBP≥140mmHg and DOS SBP≥146mmHg had 95.9% estimated specificity (95% CI 94.4 to 97.0) for identifying subsequent primary care SBP≥140mmHg and estimated sensitivity of 26.8% (95% CI 22.0 to 32.0). A similarly high specificity using a single DOS SBP required a threshold SBP≥160mmHg, for which estimated specificity was 95.2% (95% CI 94.2 to 96.1). For DBP, a presenting DOS DBP≥92mmHg had 95.7% specificity (95% CI 94.8 to 96.4) for subsequent primary care DBP≥90mmHg with a sensitivity of 18.8% (95% CI 14.4 to 24.0).
Conclusion
A small bias toward higher DOS blood pressures relative to subsequent primary care measurements was observed. DOS factors predicted only a small proportion of the observed variation. Accounting for the observed bias, a two-stage SBP threshold and a single-reading DBP threshold were highly specific though insensitive for identifying subsequent primary care blood pressure elevation.
doi:10.1213/ANE.0b013e318239c4c1
PMCID: PMC3282161  PMID: 22075017
10.  Quality Control and Validation of Oscillometric Blood Pressure Measurements Taken During an Epidemiological Investigation 
Medicine  2015;94(37):e1475.
Supplemental Digital Content is available in the text
Abstract
This study aims to validate blood pressure (BP) values measured by an oscillometric BP monitor and seek possible calibration methods if discrepancies exist.
Noninvasive BP measurement outcomes were determined using an oscillometric BP monitor (Omron HBP-1300) versus a mercury sphygmomanometer (standard device). Two percent of subjects enrolled in an epidemiological investigation were systematically sampled in this study. Intraclass correlation coefficient (ICC) was used to evaluate measurement reliability, paired t-test was used to evaluate trueness, and linear regression was used for calibration. The Association for the Advancement of Medical Instrumentation (AAMI) standards and British Hypertension Society (BHS) protocols were used for validation quality assessment.
Both mercury sphygmomanometer (standard device) and oscillometric BP monitor (test device) displayed high reliability. A significant difference in systolic blood pressure (SBP) was observed between devices. SBP calibration was achieved by using an effective linear regression model (B = 0.803 and constant = 19.592, P < 0.001). The calibrated model was corroborated by verification samples (P = 0.120) and was found to pass AAMI standards and BHS protocol requirements.
Calibrated SBP measurements from the Omron HBP-1300 device were valid. Use of a combination of statistical methods, such as ICC for reliability assessment as well as paired t-test for trueness evaluation can be used to validate data from the oscillometric BP monitors.
doi:10.1097/MD.0000000000001475
PMCID: PMC4635802  PMID: 26376388
11.  Twenty-Four-Hour Ambulatory Blood Pressure Monitoring in Hypertension 
Executive Summary
Objective
The objective of this health technology assessment was to determine the clinical effectiveness and cost-effectiveness of 24-hour ambulatory blood pressure monitoring (ABPM) for hypertension.
Clinical Need: Condition and Target Population
Hypertension occurs when either systolic blood pressure, the pressure in the artery when the heart contracts, or diastolic blood pressure, the pressure in the artery when the heart relaxes between beats, are consistently high. Blood pressure (BP) that is consistently more than 140/90 mmHg (systolic/diastolic) is considered high. A lower threshold, greater than 130/80 mmHg (systolic/diastolic), is set for individuals with diabetes or chronic kidney disease.
In 2006 and 2007, the age-standardized incidence rate of diagnosed hypertension in Canada was 25.8 per 1,000 (450,000 individuals were newly diagnosed). During the same time period, 22.7% of adult Canadians were living with diagnosed hypertension.
A smaller proportion of Canadians are unaware they have hypertension; therefore, the estimated number of Canadians affected by this disease may be higher. Diagnosis and management of hypertension are important, since elevated BP levels are related to the risk of cardiovascular disease, including stroke. In Canada in 2003, the costs to the health care system related to the diagnosis, treatment, and management of hypertension were over $2.3 billion (Cdn).
Technology
The 24-hour ABPM device consists of a standard inflatable cuff attached to a small computer weighing about 500 grams, which is worn over the shoulder or on a belt. The technology is noninvasive and fully automated. The device takes BP measurements every 15 to 30 minutes over a 24-to 28-hour time period, thus providing extended, continuous BP recordings even during a patient’s normal daily activities. Information on the multiple BP measurements can be downloaded to a computer.
The main detection methods used by the device are auscultation and oscillometry. The device avoids some of the pitfalls of conventional office or clinic blood pressure monitoring (CBPM) using a cuff and mercury sphygmomanometer such as observer bias (the phenomenon of measurement error when the observer overemphasizes expected results) and white coat hypertension (the phenomenon of elevated BP when measured in the office or clinic but normal BP when measured outside of the medical setting).
Research Questions
Is there a difference in patient outcome and treatment protocol using 24-hour ABPM versus CBPM for uncomplicated hypertension?
Is there a difference between the 2 technologies when white coat hypertension is taken into account?
What is the cost-effectiveness and budget impact of 24-hour ABPM versus CBPM for uncomplicated hypertension?
Research Methods
Literature Search
Search Strategy
A literature search was performed on August 4, 2011 using OVID MEDLINE, MEDLINE In-Process and Other Non-Indexed Citations, EMBASE, the Cumulative Index to Nursing and Allied Health Literature (CINAHL), the Cochrane Library, and the International Agency for Health Technology Assessment (INAHTA) for studies published from January 1, 1997 to August 4, 2011. Abstracts were reviewed by a single reviewer. For those studies meeting the eligibility criteria, full-text articles were obtained. Reference lists were also examined for any additional relevant studies not identified through the search. Articles with unknown eligibility were reviewed with a second clinical epidemiologist and then a group of epidemiologists until consensus was established. The quality of evidence was assessed as high, moderate, low, or very low according to GRADE methodology.
Inclusion Criteria
English language articles;
published between January 1, 1997 and August 4, 2011;
adults aged 18 years of age or older;
journal articles reporting on the effectiveness, cost-effectiveness, or safety for the comparison of interest;
clearly described study design and methods;
health technology assessments, systematic reviews, meta-analyses, or randomized controlled trials.
Exclusion Criteria
non-English papers;
animal or in vitro studies;
case reports, case series, or case-case studies;
studies comparing different antihypertensive therapies and evaluating their antihypertensive effects using 24-hour ABPM;
studies on home or self-monitoring of BP, and studies on automated office BP measurement;
studies in high-risk subgroups (e.g. diabetes, pregnancy, kidney disease).
Outcomes of Interest
Patient Outcomes
mortality: all cardiovascular events (e.g., myocardial infarction [MI], stroke);
non-fatal: all cardiovascular events (e.g., MI, stroke);
combined fatal and non-fatal: all cardiovascular events (e.g., MI, stroke);
all non-cardiovascular events;
control of BP (e.g. systolic and/or diastolic target level).
Drug-Related Outcomes
percentage of patients who show a reduction in, or stop, drug treatment;
percentage of patients who begin multi-drug treatment;
drug therapy use (e.g. number, intensity of drug use);
drug-related adverse events.
Quality of Evidence
The quality of the body of evidence was assessed as high, moderate, low, or very low according to the GRADE Working Group criteria.
As stated by the GRADE Working Group, the following definitions of quality were used in grading the quality of the evidence:
Summary of Findings
Short-Term Follow-Up Studies (Length of Follow-Up of ≤ 1 Year)
Based on very low quality of evidence, there is no difference between technologies for non-fatal cardiovascular events.
Based on moderate quality of evidence, ABPM resulted in improved BP control among patients with sustained hypertension compared to CBPM.
Based on low quality of evidence, ABPM resulted in hypertensive patients being more likely to stop antihypertensive therapy and less likely to proceed to multi-drug therapy compared to CBPM.
Based on low quality of evidence, there is a beneficial effect of ABPM on the intensity of antihypertensive drug use compared to CBPM.
Based on moderate quality of evidence, there is no difference between technologies in the number of antihypertensive drugs used.
Based on low to very low quality of evidence, there is no difference between technologies in the risk for a drug-related adverse event or noncardiovascular event.
Long-Term Follow-Up Study (Mean Length of Follow-Up of 5 Years)
Based on moderate quality of evidence, there is a beneficial effect of ABPM on total combined cardiovascular events compared to CBPM.
Based on low quality of evidence, there is a lack of a beneficial effect of ABPM on nonfatal cardiovascular events compared to CBPM; however, the lack of a beneficial effect is based on a borderline result.
Based on low quality of evidence, there is no beneficial effect of ABPM on fatal cardiovascular events compared to CBPM.
Based on low quality of evidence, there is no difference between technologies for the number of patients who began multi-drug therapy.
Based on low quality of evidence, there is a beneficial effect of CBPM on control of BP compared to ABPM. This result is in the opposite direction than expected.
Based on moderate quality of evidence, there is no difference between technologies in the risk for a drug-related adverse event.
PMCID: PMC3377518  PMID: 23074425
12.  Validation of the custo screen 400 ambulatory blood pressure-monitoring device according to the European Society of Hypertension International Protocol revision 2010 
Objective
The aim of the present study was to validate the custo screen 400 ambulatory blood pressure-monitoring (ABPM) device according to the 2010 International Protocol revision of the European Society of Hypertension (ESH-IP). The device can be used for ABPM for up to 72 hours.
Materials and methods
Systolic and diastolic blood pressure (SBP and DBP, respectively) were sequentially measured in 33 adult subjects (13 males and 20 females) and compared with a standard mercury sphygmomanometer (two observers). A total of 99 comparison pairs were obtained.
Results
The custo screen 400 met the requirements of parts 1 and 2 of the ESH-IP revision 2010. The mean difference between the device and reference sphygmomanometer readings was −0.5±4.5 mmHg for SBP and −0.1±3.3 mmHg for DBP. All but one measurement were within the absolute difference of 10 mmHg between the device and the observers for SBP and DBP. The number of absolute differences between the device and the observers within a range of 5 mmHg was 84 of 99 readings for SBP, and 93 of 99 readings for DBP.
Conclusion
The custo screen 400 ABPM device met the requirements of the 2010 ESH-IP revision, and hence can be recommended for ABPM in adults. To our knowledge, the custo screen 400 is the first device to pass the revised ESH-IP 2010.
doi:10.2147/VHRM.S63602
PMCID: PMC4027883  PMID: 24868162
validation; ambulatory blood pressure monitoring; ESH
13.  Assessing agreement of blood pressure-measuring devices in Tibetan areas of China: a systematic review 
Heart Asia  2016;8(2):46-51.
Background
The validity of blood pressure (BP)-measuring tools at very high altitudes is uncertain. Therefore, the objective of this review was to examine the degree of agreement of BP-measuring devices in Tibet.
Methods
We conducted electronic searches in Medline, Embase, Cinahl, Cochrane Library, Global Health Library and the ISI Web of Science. Randomised and observational studies were considered for inclusion. The methodological characteristics of included studies were assessed using the Quality Assessment of Diagnostic Accuracy Studies-2 criteria. Our primary outcome was the difference in mean BP measurements between the new device and the gold standard.
Results
We identified three eligible studies, out of which two with a total of 162 participants were included. The studies differed in their methodology. One study reported significantly higher systolic blood pressure (SBP) measurement with electronic sphygmomanometer (Omron) compared with mercury sphygmomanometer (mean difference 5.8±4.7 mm Hg; p<0.001), with no significant difference in diastolic blood pressure (DBP) measurement (0.4±3.9 mm Hg; p=0.23). The second study reported mean differences of 1.0±5.9 mm Hg and −3.1±4.6 mm Hg for SBP and DBP, respectively.
Conclusion
The limited evidence from published studies suggests that automated (Omron) BP monitors show a high degree of agreement for DBP when compared against mercury sphygmomanometer at high altitudes. However, the degree of such agreement for SBP is not consistent. Few studies assessing the validity of automated BP monitors at high altitudes have been conducted, and they differ in design and methodology. Further research assessing the suitability of BP-measuring instruments at high altitudes is therefore warranted.
doi:10.1136/heartasia-2016-010798
PMCID: PMC5093356  PMID: 27843497
EBM; HYPERTENSION
14.  Life Course Trajectories of Systolic Blood Pressure Using Longitudinal Data from Eight UK Cohorts 
PLoS Medicine  2011;8(6):e1000440.
Analysis of eight population-based and occupational cohorts from the UK reveals the patterns of change of blood pressure in the population through the life course.
Background
Much of our understanding of the age-related progression of systolic blood pressure (SBP) comes from cross-sectional data, which do not directly capture within-individual change. We estimated life course trajectories of SBP using longitudinal data from seven population-based cohorts and one predominantly white collar occupational cohort, each from the United Kingdom and with data covering different but overlapping age periods.
Methods and Findings
Data are from 30,372 individuals and comprise 102,583 SBP observations spanning from age 7 to 80+y. Multilevel models were fitted to each cohort. Four life course phases were evident in both sexes: a rapid increase in SBP coinciding with peak adolescent growth, a more gentle increase in early adulthood, a midlife acceleration beginning in the fourth decade, and a period of deceleration in late adulthood where increases in SBP slowed and SBP eventually declined. These phases were still present, although at lower levels, after adjusting for increases in body mass index though adulthood. The deceleration and decline in old age was less evident after excluding individuals who had taken antihypertensive medication. Compared to the population-based cohorts, the occupational cohort had a lower mean SBP, a shallower annual increase in midlife, and a later midlife acceleration. The maximum sex difference was found at age 26 (+8.2 mm Hg higher in men, 95% CI: 6.7, 9.8); women then experienced steeper rises and caught up by the seventh decade.
Conclusions
Our investigation shows a general pattern of SBP progression from childhood in the UK, and suggests possible differences in this pattern during adulthood between a general population and an occupational population.
Please see later in the article for the Editors' Summary
Editors' Summary
Background
About a third of US and UK adults have high blood pressure (hypertension). Although hypertension has no obvious symptoms, it can lead to life-threatening heart attacks, stroke, and other forms of cardiovascular disease (CVD). It is diagnosed by measuring blood pressure—the force that blood moving around the body exerts on the inside of large blood vessels. Blood pressure is highest when the heart is pumping out blood (systolic blood pressure [SBP]) and lowest when the heart is re-filling with blood (diastolic blood pressure [DBP]). Normal adult blood pressure is defined as an SBP of less than 130 millimeters of mercury (mm Hg) and a DBP of less than 85 mm Hg (a blood pressure of 130/85). A reading of more than 140/90 indicates hypertension. Many factors affect blood pressure, but overweight people and individuals who eat fatty or salty food are at high risk of developing hypertension. Moreover, blood pressure tends to increase with age. Mild hypertension can often be corrected by making lifestyle changes, but many people take antihypertensive drugs to reduce their blood pressure.
Why Was This Study Done?
Several trials have indicated that SBP is an important, modifiable risk factor for CVD. But, to determine the best way to prevent CVD, it is important to understand how SBP changes through life and how lifestyle factors affect this age-related progression. Textbook descriptions of age-related changes in SBP are based on studies that measured SBP at a single time point in groups (cohorts) of people of different ages. However, such “cross-sectional” studies do not capture within-individual changes in SBP and may be affected by environmental effects related to specific historical periods. The best way to measure age-related changes in SBP is through longitudinal studies in which SBP is repeatedly measured over many years in a single cohort. Such studies are underway, but it will be some decades before individuals in these studies reach old age. In this study, therefore, the researchers use data from multiple UK cohorts that had repeated SBP measurements taken over different but overlapping periods of life to investigate the life course trajectory of SBP.
What Did the Researchers Do and Find?
The researchers used statistical models to analyze data from longitudinal studies of SBP in seven population-based cohorts (the participants were randomly chosen from the general population) and in one occupational cohort (civil servants). SBP measurements were available for 30,372 individuals with ages spanning from seven years to more than 80 years. The researchers' analysis revealed four phases of SBP change in both sexes: a rapid increase in SBP during adolescent growth, a gentler increase in early adulthood, a midlife acceleration beginning in the fourth decade of life, and a period in late adulthood when SBP increases slowed and then reversed. This last phase was less marked when people taking antihypertensive drugs were excluded from the analysis. After adjusting for increases in body mass index (a measure of body fat) during adulthood, the magnitude of the SBP age-related changes was similar but the average SBP at each age was lower. Compared to the population-based cohorts, the occupational cohort had a lower average SBP, a shallower annual increase in SBP, and a later midlife acceleration, possibly because of socially determined modifiable SBP-related factors such as diet and lifestyle. Finally, although women had lower SBPs in early adulthood than men, they experienced steeper midlife SBP rises (probably because of a menopause-related effect on salt sensitivity) so that by the seventh decade of life, men and women had similar average SBPs.
What Do These Findings Mean?
These findings describe the general pattern of age-related progression of SBP from early childhood in the UK. The findings may not be generalizable because other populations may be exposed to different distributions of modifiable factors. In addition, their accuracy may be affected by differences between cohorts in how SBP was measured. Nevertheless, these findings—in particular, the slower midlife increase in SBP in the occupational cohort than in the population-based cohorts—suggest that the key determinants of age-related increases in blood pressure are modifiable and could be targeted for CVD prevention. Further research is now needed to identify exactly which factors affect the life course trajectory of SBP and to discover when these factors have their greatest influence on SBP.
Additional Information
Please access these Web sites via the online version of this summary at http://dx.doi.org/10.1371/journal.pmed.1000440.
The US National Heart Lung and Blood Institute has patient information about high blood pressure (in English and Spanish)
The American Heart Association provides information on high blood pressure and on cardiovascular diseases (in several languages)
The UK National Health Service Choices Web site also provides detailed information for patients about hypertension and about cardiovascular disease
MedlinePlus provides links to further information about high blood pressure, heart disease, and stroke (in English and Spanish)
doi:10.1371/journal.pmed.1000440
PMCID: PMC3114857  PMID: 21695075
15.  How Accurate Are Home Blood Pressure Devices in Use? A Cross-Sectional Study 
PLoS ONE  2016;11(6):e0155677.
Background
Out of office blood pressure measurements, using either home monitors or 24 hour ambulatory monitoring, is widely recommended for management of hypertension. Though validation protocols, meant to be used by manufacturers, exist for blood pressure monitors, there is scant data in the literature about the accuracy of home blood pressure monitors in actual clinical practice. We performed a chart review in the blood pressure assessment clinic at a tertiary care centre.
Methods
We assessed the accuracy of home blood pressure monitors used by patients seen in the nephrology clinic in Ottawa between the years 2011 to 2014. We recorded patient demographics and clinical data, including the blood pressure measurements, arm circumference and the manufacturer of the home blood pressure monitor. The average of BP measurements performed with the home blood pressure monitor, were compared to those with the mercury sphygmomanometer. We defined accuracy based on a difference of 5 mm Hg in the blood pressure values between the home monitor and mercury sphygmomanometer readings. The two methods were compared using a Bland-Altman plot and a student’s t-test.
Results
The study included 210 patients. The mean age of the study population was 67 years and 61% was men. The average mid-arm circumference was 32.2 cms. 30% and 32% of the home BP monitors reported a mean systolic and diastolic BP values, respectively, different from the mercury measurements by 5 mm Hg or more. There was no significant difference between the monitors that were accurate versus those that were not when grouped according to the patient characteristics, cuff size or the brand of the home monitor.
Conclusions
An important proportion of home blood pressure monitors used by patients seen in our nephrology clinic were inaccurate. A re-validation of the accuracy and safety of the devices already in use is prudent before relying on these measurements for clinical decisions.
doi:10.1371/journal.pone.0155677
PMCID: PMC4889144  PMID: 27249056
16.  Is it reliable to measure the forearm blood pressure in children? 
Background:
When the upper arm (UA) is inaccessible or a standard-sized blood pressure (BP) cuff is unavailable, some healthcare workers use the forearm (FA) to measure BP with a mercury sphygmomanometer.
Objective:
The objective was to determine the accuracy of BP measurement in the arm and FA.
Design:
Prospective, randomized study.
Setting:
Department of Pediatrics, JNMC, Sawangi (Meghe)
Participants:
A total of 72 children aged 5–15 years.
Measurements:
Mercury and Automatic (OMRON Tokyo, 108-0075 Japan) BP measurements were recorded from the arm and FA at 2 min intervals.
Results:
In our study, 72 children of both sexes were enrolled. The mean age of the children was 10.13 ± 2.82 years, and 48% were females. Pearson's correlation coefficient between FA and UA systolic BP (SBP) measured by mercury was 0.782, and for diastolic BP (DBP) it was 0.824. Similarly, Pearson's correlation coefficient between FA and UA SBP measured with an automated device (OMRON) was 0.843, and for DBP it was 0.846. The average readings for the SBP and DBP were higher in the FA than in the UA by approximately 3 mmHg. There was a statistically significant difference in both SBP and DBP.
Conclusions:
The FA is an acceptable method of BP monitoring when the UA cannot be accessed. The pressure from FA is probably higher than it would be from UA.
doi:10.4103/2230-8229.155376
PMCID: PMC4415132  PMID: 25983603
Blood pressure; forearm; OMRON; upper arm
17.  Evaluation des sphygmomanomètres utilisés par les médecins de famille en milieu extra-hospitalier du Bas-Saint-Laurent. 
Canadian Family Physician  2001;47:281-286.
OBJECTIVE: To assess the precision and integrity of all aneroid and mercury sphygmomanometers regularly used by family physicians practising outside hospitals. DESIGN: Cross-sectional study. SETTING: Private medical clinics and local community health centres in Bas-Saint-Laurent, Qué. PARTICIPANTS: A total of 151 of the 166 physicians in this administrative region. MAIN OUTCOME MEASURES: Precision of the mercury sphygmomanometers was measured using the difference between a reading in the absence of pressure and level 0. Precision of the aneroid sphygmomanometers was measured using variations at pressures of 140 mm Hg and 90 mm Hg compared with those on a calibrated mercury sphygmomanometer. Integrity of sphygmomanometers, arm cuffs, and inflating bulbs was also assessed. RESULTS: In all, 258 sphygmomanometers met the inclusion criteria (111 mercury sphygmomanometers and 147 aneroid sphygmomanometers). Discrepancies of > or = 4 mm Hg were found in 15.5% of these instruments (12.6% and 17.7% of the mercury and aneroid sphygmomanometers, respectively). In 31.0% of the instruments (52.3% and 15.0% of the mercury and aneroid sphygmomanometers, respectively), one component was malfunctioning. CONCLUSION: Sphygmomanometers that measure patients' blood pressure inaccurately could result in an incorrect diagnosis of hypertension or in a normal blood pressure reading in a hypertensive patient.
PMCID: PMC2016254  PMID: 11228028
18.  Agreement of Blood Pressure Measurements between Random-Zero and Standard Mercury Sphygmomanometers 
The random-zero sphygmomanometer has been widely used in observational studies and clinical trials for blood pressure measurement. We examined the agreement of blood pressure measurements between random-zero and standard mercury sphygmomanometers among 2,007 Chinese study participants aged 15–60 years. Three blood pressure readings were obtained by trained observers using random-zero and standard mercury sphygmomanometers, respectively, in a random order. Overall, blood pressure readings obtained using the random-zero device were significantly lower than those obtained with the standard mercury sphygmomanometer, with a mean difference ranging from −3.0 to −2.7 mm Hg for systolic and −1.4 to −0.9 mm Hg for diastolic blood pressure (all p <0.01). Correlation coefficients between mean blood pressure measurements obtained using the random-zero and standard mercury sphygmomanometers were high (0.90 for systolic and 0.85 for diastolic blood pressure, both p< 0.0001). In conclusion, our study indicated that there was strong agreement between blood pressure measurements obtained using the random-zero and standard mercury sphygmomanometers although blood pressure values were on average lower with the random-zero sphygmomanometer.
doi:10.1097/MAJ.0b013e31816956ac
PMCID: PMC2587170  PMID: 19011391
blood pressure measurements; random-zero sphygmomanometer; standard mercury sphygmomanometer; agreement
19.  A new automatic blood pressure kit auscultates for accurate reading with a smartphone 
Medicine  2016;95(32):e4538.
Abstract
The widely used oscillometric automated blood pressure (BP) monitor was continuously questioned on its accuracy. A novel BP kit named Accutension which adopted Korotkoff auscultation method was then devised. Accutension worked with a miniature microphone, a pressure sensor, and a smartphone. The BP values were automatically displayed on the smartphone screen through the installed App. Data recorded in the phone could be played back and reconfirmed after measurement. They could also be uploaded and saved to the iCloud. The accuracy and consistency of this novel electronic auscultatory sphygmomanometer was preliminarily verified here. Thirty-two subjects were included and 82 qualified readings were obtained. The mean differences ± SD for systolic and diastolic BP readings between Accutension and mercury sphygmomanometer were 0.87 ± 2.86 and −0.94 ± 2.93 mm Hg. Agreements between Accutension and mercury sphygmomanometer were highly significant for systolic (ICC = 0.993, 95% confidence interval (CI): 0.989–0.995) and diastolic (ICC = 0.987, 95% CI: 0.979–0.991). In conclusion, Accutension worked accurately based on our pilot study data. The difference was acceptable. ICC and Bland–Altman plot charts showed good agreements with manual measurements. Systolic readings of Accutension were slightly higher than those of manual measurement, while diastolic readings were slightly lower. One possible reason was that Accutension captured the first and the last korotkoff sound more sensitively than human ear during manual measurement and avoided sound missing, so that it might be more accurate than traditional mercury sphygmomanometer. By documenting and analyzing of variant tendency of BP values, Accutension helps management of hypertension and therefore contributes to the mobile heath service.
doi:10.1097/MD.0000000000004538
PMCID: PMC4985331  PMID: 27512876
auscultation; blood pressure monitor; hypertension; smartphone; sphygmomanometer
20.  Blood pressure and its associated factors among primary school children in suburban Selangor, Malaysia: A cross-sectional survey 
Background:
Little is known about the relationship of blood pressure (BP) with adiposity indicators, dietary habits, physical activity, and sleep in school children in Malaysia. We aimed to study about the distribution of BP and its associated factors in primary school children.
Materials and Methods:
A survey was carried out on a random sample of 335 children in five primary schools. BP was measured with a mercury sphygmomanometer. Anthropometry was done by standard methods. Demographic information, dietary habits, physical activity, and duration of sleep were collected by interviews. World Health Organization classification based on body mass index (BMI) and waist circumference (WC) cut-offs were used to define overweight/obesity. Elevated BP was defined according to US reference standards.
Results:
A total 335 children (144 boys and 191 girls) were examined. Their mean age was 9.18 years (standard deviation [SD] = 0.28). Overall mean systolic blood pressure (SBP) and mean diastolic blood pressure (DBP) were 99.32 mmHg (SD = 10.79) and 67.11 mmHg (SD = 10.76), respectively. Mean BMI and WC were 16.39 (SD = 3.58) and 57.77 cm (SD = 8.98), respectively. The prevalence of pre-hypertension was 12.23% (95% confidence intervals [CIs] 8.73, 15.75) and hypertension was 13.4% (95% CIs 9.78, 17.09). Mean SBP and DBP was higher among overweight and obese children than normal children. By multivariate linear regression analyses, BMI (β = 0.250, P = 0.049) and WC (β = 0.308, P = 0.015) were positively associated with SBP; age (β = 0.111, P = 0.017), BMI (β = 0.320, P = 0.012) were positively associated with DBP but total (weekly) hours of sleep (β = −0.095, P = 0.037) was negatively associated with DBP.
Conclusion:
BP was associated with BMI and WC. Health promotion activities should be initiated in primary schools.
doi:10.4103/2230-8229.114769
PMCID: PMC3748653  PMID: 23983560
Blood pressure; body mass index; cross-sectional survey; obesity; school children; waist circumference
21.  Validation of Omron RS8, RS6, and RS3 home blood pressure monitoring devices, in accordance with the European Society of Hypertension International Protocol revision 2010 
Background
Allowing patients to measure their blood pressure at home is recognized as being of clinical value. However, it is not known how often these measurements are taken correctly. Blood pressure monitors for home use fall into two types based on the position of the cuff, ie, at the upper arm or the wrist. The latter is particularly convenient, as measurements can be taken fully clothed. This study aimed to evaluate the performance of the wrist-type blood pressure monitors Omron RS8 (HEM-6310F-E), Omron RS6 (HEM-6221-E), and Omron RS3 (HEM-6130-E).
Methods
A team of three trained doctors validated the performance of these devices by comparing the measurements obtained from these devices with those taken using a standard mercury sphygmomanometer. All the devices met the validation requirements of the European Society of Hypertension International Protocol revision 2010.
Results
The difference in blood pressure readings between the tested device and the standard mercury sphygmomanometer was within 3 mmHg, which is acceptable according to the European Society of Hypertension guidelines.
Conclusion
All the home devices tested were found to be suitable for measuring blood pressure at home because their performance fulfilled the requirement of the guidelines.
doi:10.2147/VHRM.S44569
PMCID: PMC3671796  PMID: 23745050
blood pressure; device; European Society of Hypertension; guideline; measurement; validation
22.  The association between blood pressure and whole blood methylmercury in a cross-sectional study among Inuit in Greenland 
Environmental Health  2012;11:44.
Background
The Inuit in Greenland have a high average consumption of marine species and are highly exposed to methylmercury, which in other studies has been related to hypertension. Data on the relation between methylmercury and hypertension is limited, especially in populations subjected to a high exposure of methylmercury. We examined the relation between whole blood mercury and blood pressure (BP) in Inuit in Greenland.
Methods
A cross-sectional population-based study among adult Inuit in Greenland was performed in 2005–2009. Information on socio-demography, lifestyle, BP, blood samples and clinical measurements was obtained – the latter after overnight fasting. BP was measured according to standardized guidelines. Whole blood mercury concentration was used as a marker of exposure. The analyses were restricted to Inuit aged 30–69 years with four Greenlandic grandparents (N = 1,861). Multivariate regression analyses with inclusion of confounders were done separately for men and women with the omission of participants receiving anti-hypertensive drugs, except for logistic regression analyses of the relation between mercury and presence of hypertension (yes/no).
Results
The mean whole blood mercury level was 20.5 μg/L among men and 14.7 μg/L among women. In multivariate analyses adjusted for confounders, diastolic BP decreased with increasing mercury concentration. In men diastolic BP decreased significantly for each four-fold increase in mercury concentration (Beta = −0.04, standard error = 0.01, p = 0.001), while no relation between mercury and diastolic BP was found among women. For systolic BP, a similar non-statistically significant result was seen only for men (Beta = −0.02, standard error = 0.01, p = 0.06). A relation between mercury and hypertension was only found in men; the odds ratio for hypertension was 0.99 (95% CI: 0.98-0.99). No relation between quintiles of mercury and hypertension was found. The relationship between mercury and BP parameters may be non-linear: In analyses of quintiles of mercury the overall effect of mercury on BP parameters was only statistically significant for diastolic BP among men (Wald test, p = 0.01), however pairwise comparisons showed that some quintiles were not statistically different. This result is supported by LOESS modelling.
Conclusions
No adverse associations between whole blood mercury and blood pressure were found. With increasing whole blood mercury concentrations, diastolic BP and the risk of hypertension decreased among men in the study: this may be explained by confounding by exercise or unknown factors.
doi:10.1186/1476-069X-11-44
PMCID: PMC3403910  PMID: 22747793
Whole blood mercury; Blood pressure; Hypertension; Inuit; Greenland
23.  The Influence of Health Systems on Hypertension Awareness, Treatment, and Control: A Systematic Literature Review 
PLoS Medicine  2013;10(7):e1001490.
Will Maimaris and colleagues systematically review the evidence that national or regional health systems, including place of care and medication co-pays, influence hypertension awareness, treatment, and control.
Please see later in the article for the Editors' Summary
Background
Hypertension (HT) affects an estimated one billion people worldwide, nearly three-quarters of whom live in low- or middle-income countries (LMICs). In both developed and developing countries, only a minority of individuals with HT are adequately treated. The reasons are many but, as with other chronic diseases, they include weaknesses in health systems. We conducted a systematic review of the influence of national or regional health systems on HT awareness, treatment, and control.
Methods and Findings
Eligible studies were those that analyzed the impact of health systems arrangements at the regional or national level on HT awareness, treatment, control, or antihypertensive medication adherence. The following databases were searched on 13th May 2013: Medline, Embase, Global Health, LILACS, Africa-Wide Information, IMSEAR, IMEMR, and WPRIM. There were no date or language restrictions. Two authors independently assessed papers for inclusion, extracted data, and assessed risk of bias. A narrative synthesis of the findings was conducted. Meta-analysis was not conducted due to substantial methodological heterogeneity in included studies. 53 studies were included, 11 of which were carried out in LMICs. Most studies evaluated health system financing and only four evaluated the effect of either human, physical, social, or intellectual resources on HT outcomes. Reduced medication co-payments were associated with improved HT control and treatment adherence, mainly evaluated in US settings. On balance, health insurance coverage was associated with improved outcomes of HT care in US settings. Having a routine place of care or physician was associated with improved HT care.
Conclusions
This review supports the minimization of medication co-payments in health insurance plans, and although studies were largely conducted in the US, the principle is likely to apply more generally. Studies that identify and analyze complexities and links between health systems arrangements and their effects on HT management are required, particularly in LMICs.
Please see later in the article for the Editors' Summary
Editors' Summary
Background
In 2008, one billion people, three-quarters of whom were living in low- and middle-income countries, had high blood pressure (hypertension). Worldwide, hypertension, which rarely has any symptoms, leads to about 7.5 million deaths annually from heart attacks, stroke, other cardiovascular diseases, and kidney disease. Hypertension, selected by the World Health Organization as the theme for World Health Day 2013, is diagnosed by measuring blood pressure, the force that blood circulating in the body exerts on the inside of large blood vessels. Blood pressure is highest when the heart is contracts to pump blood out (systolic blood pressure) and lowest when the heart relaxes and refills (diastolic blood pressure). Normal adult blood pressure is defined as a systolic blood pressure of less than 120 millimeters of mercury (mmHg) and a diastolic blood pressure of less than 80 mmHg (a blood pressure of less than 120/80 mmHg). A blood pressure reading of more than 140/90 mmHg indicates hypertension. Many factors affect blood pressure, but overweight people and individuals who eat fatty or salty foods are at high risk of developing hypertension.
Why Was This Study Done?
Most individuals can achieve good hypertension control, which reduces death and disability from cardiovascular and kidney disease, by making lifestyle changes (mild hypertension) and/or by taking antihypertensive drugs. Yet, in both developed and developing countries, many people with hypertension are not aware of their condition and are not adequately treated. As with other chronic diseases, weaknesses in health care systems probably contribute to the inadequate treatment of hypertension. A health care system comprises all the organizations, institutions, and resources whose primary purpose is to improve health. Weaknesses in health care systems can exist at the national, regional, district, community, and household level. In this systematic review (a study that uses predefined criteria to identify all the research on a given topic), the researchers investigate how national and regional health care system arrangements influence hypertension awareness, treatment, and control. Actions that might influence hypertension care at this level of health care systems include providing treatment for hypertension at no or reduced cost, the introduction of financial incentives to healthcare practitioners for the diagnosis and treatment of hypertension, and enhanced insurance coverage in countries such as the US where people pay for health care through insurance policies.
What Did the Researchers Do and Find?
The researchers identified 53 studies that analyzed whether regional or national health care systems arrangements were associated with patient awareness of hypertension, treatment of hypertension, adherence to antihypertensive medication treatment, and control of hypertension. The researchers used an established conceptual framework for health care systems and an approach called narrative synthesis to analyze the results of these studies, most of which were conducted in the US (36 studies) and other high-income countries (eight studies). Nearly all the studies evaluated the effects of health system financing on hypertension outcomes, although several looked at the effects of delivery and governance of health systems on these outcomes. The researchers' analysis revealed an association between reduced medication co-payments (drug costs that are not covered by health insurance and that are paid by patients in countries without universal free healthcare) and improved hypertension control and treatment adherence, mainly in US settings. In addition, in US settings, health insurance coverage was associated with improved hypertension outcomes, as was having a routine physician or place of care.
What Do These Findings Mean?
These findings suggest that minimizing co-payments for health care and expansion of health insurance coverage in countries without universal free health care may improve the awareness, treatment, and control of hypertension. Although these findings are based mainly on US studies, they are likely to apply more generally but, importantly, these findings indicate that additional, high-quality studies are needed to unravel the impact of health systems arrangements on the management of hypertension. In particular, they reveal few studies in low- and middle-income countries where most of the global burden of hypertension lies and where weaknesses in health systems often result in deficiencies in the care of chronic diseases. Moreover, they highlight a need for studies that evaluate how aspects of health care systems other than financing (for example, delivery and governance mechanisms) and interactions between health care system arrangements affect hypertension outcomes. Without the results of such studies, governments and national and international organizations will not know the best ways to deal effectively with the global public-health crisis posed by hypertension.
Additional Information
Please access these Web sites via the online version of this summary at http://dx.doi.org/10.1371/journal.pmed.1001490.
The US National Heart Lung and Blood Institute has patient information about high blood pressure (in English and Spanish)
The American Heart Association provides information on high blood pressure (in several languages) and personal stories about dealing with high blood pressure
The UK National Health Service (NHS) Choices website provides detailed information for patients about hypertension and a personal story about hypertension
The World Health Organization provides information on controlling blood pressure and on health systems (in several languages); its "A Global Brief on Hypertension" was published on World Health Day 2013
MedlinePlus provides links to further information about high blood pressure (in English and Spanish)
doi:10.1371/journal.pmed.1001490
PMCID: PMC3728036  PMID: 23935461
24.  Cardiac autonomic activity and blood pressure among Nunavik Inuit adults exposed to environmental mercury: a cross-sectional study 
Environmental Health  2008;7:29.
Background
Mercury is a contaminant that reaches high levels in Nunavik (North of Quebec). It is transformed into methylmercury (MeHg) and accumulated in marine mammals and predator fish, an important part of the traditional Inuit diet. MeHg has been suggested to affect BP in adults and children while the influence on HRV has only been studied in children. We aimed to assess the impact of MeHg levels on HRV and BP in Inuit adults from Nunavik.
Methods
In the fall of 2004, the «Qanuippitaa?» Health Survey was conducted in Nunavik (Quebec, Canada) and information on HRV was collected among 280 adults aged 40 years and older. Indicators of the time and frequency domains of HRV were derived from a 2-hour Holter recording. BP was measured according to the Canadian Coalition for High Blood Pressure technique. Pulse pressure (PP) was the difference between systolic (SBP) and diastolic blood pressure (DBP). Blood mercury concentration was used as exposure biomarker. Statistical analysis was conducted through linear regression and multivariable linear regression was used to control for confounders.
Results
Mercury was negatively correlated with low frequency (LF) (r = -0.18; p = 0.02), the standard deviation of RR intervals (SDNN) (r = -0.14; p = 0.047) and the coefficient of variation of RR intervals (CVRR) (r = -0.18; p = 0.011) while correlations with other HRV parameters did not reach statistical significance. After adjusting for confounders, the association with LF (beta = -0.006; p = 0.93) became non significant. However, the association with SDANN became statistically significant (beta = -0.086; p = 0.026) and CVRR tended to decrease with blood mercury concentrations (beta = -0.057; p = 0.056). Mercury was positively correlated with SBP (r = 0.25; p < 0.0001) and PP (r = 0.33; p < 0.0001). After adjusting for confounders, these associations remained statistically significant (beta SBP = 4.77; p = 0.01 and beta PP = 3.40; p = 0.0036). Moreover, most of the HRV parameters correlated well with BP although SBP the best before adjustment for mercury exposure.
Conclusion
The results of this study suggest a deleterious impact of mercury on BP and HRV in adults. SBP and PP increased with blood mercury concentrations while SDANN decreased with blood mercury concentrations.
doi:10.1186/1476-069X-7-29
PMCID: PMC2443124  PMID: 18538022
25.  Alcohol Intake and Blood Pressure: A Systematic Review Implementing a Mendelian Randomization Approach 
PLoS Medicine  2008;5(3):e52.
Background
Alcohol has been reported to be a common and modifiable risk factor for hypertension. However, observational studies are subject to confounding by other behavioural and sociodemographic factors, while clinical trials are difficult to implement and have limited follow-up time. Mendelian randomization can provide robust evidence on the nature of this association by use of a common polymorphism in aldehyde dehydrogenase 2 (ALDH2) as a surrogate for measuring alcohol consumption. ALDH2 encodes a major enzyme involved in alcohol metabolism. Individuals homozygous for the null variant (*2*2) experience adverse symptoms when drinking alcohol and consequently drink considerably less alcohol than wild-type homozygotes (*1*1) or heterozygotes. We hypothesise that this polymorphism may influence the risk of hypertension by affecting alcohol drinking behaviour.
Methods and Findings
We carried out fixed effect meta-analyses of the ALDH2 genotype with blood pressure (five studies, n = 7,658) and hypertension (three studies, n = 4,219) using studies identified via systematic review. In males, we obtained an overall odds ratio of 2.42 (95% confidence interval [CI] 1.66–3.55, p = 4.8 × 10−6) for hypertension comparing *1*1 with *2*2 homozygotes and an odds ratio of 1.72 (95% CI 1.17–2.52, p = 0.006) comparing heterozygotes (surrogate for moderate drinkers) with *2*2 homozygotes. Systolic blood pressure was 7.44 mmHg (95% CI 5.39–9.49, p = 1.1 × 10−12) greater among *1*1 than among *2*2 homozygotes, and 4.24 mmHg (95% CI 2.18–6.31, p = 0.00005) greater among heterozygotes than among *2*2 homozygotes.
Conclusions
These findings support the hypothesis that alcohol intake has a marked effect on blood pressure and the risk of hypertension.
Using a mendelian randomization approach Sarah Lewis and colleagues find strong support for the hypothesis that alcohol intake has a marked effect on blood pressure and the risk of hypertension.
Editors' Summary
Background.
High blood pressure (hypertension) is a common medical condition that affects nearly a third of US and UK adults. Hypertension has no symptoms but can lead to heart attacks or strokes. It is diagnosed by measuring blood pressure—the force that blood moving around the body exerts on the inside of large blood vessels. Blood pressure is highest when the heart is pumping out blood (systolic pressure) and lowest when it is filling up with blood (diastolic pressure). Normal blood pressure is defined as a systolic pressure of less than 130 millimeters of mercury (mmHg) and a diastolic pressure of less than 85 mmHg (a blood pressure of 130/85). A reading of more than 140/90 indicates hypertension. Many factors affect blood pressure, but overweight people and individuals who eat too much salty or fatty foods are at high risk of developing hypertension. Mild hypertension can often be corrected by lifestyle changes, but many people also take antihypertensive drugs to reduce their blood pressure.
Why Was This Study Done?
Another modifiable lifestyle factor thought to affect blood pressure is alcohol intake. Observational studies that ask people about their drinking habits and measure their blood pressure suggest that alcohol intake correlates with blood pressure, but they cannot prove a causal link because of “confounding”—other risk factors associated with alcohol drinking, such as diet, might also affect the study participant's blood pressures. A trial that randomly assigns people to different alcohol intakes could provide this proof of causality, but such a trial is impractical. In this study, therefore, the researchers have used “Mendelian randomization” to investigate whether alcohol intake affects blood pressure. An inactive variant of aldehyde dehydrogenase 2 (ALDH2; the enzyme that removes alcohol from the body) has been identified. People who inherit the variant form of this gene from both parents have an ALDH2 *2*2 genotype (genetic makeup) and become flushed and nauseated after drinking. Consequently, they drink less than people with a *1*2 genotype and much less than those with a *1*1 genotype. Because inheritance of these genetic variants does not affect lifestyle factors other than alcohol intake, an association between ALDH2 genotypes and blood pressure would indicate that alcohol intake has an effect on blood pressure without any confounding.
What Did the Researchers Do and Find?
The researchers identified ten published studies (mainly done in Japan where the ALDH2 gene variant is common) on associations between ALDH2 genotype and blood pressure or hypertension using a detailed search protocol (a “systematic review”). A meta-analysis (a statistical method for combining the results of independent studies) of the studies that had investigated the association between ALDH2 genotype and hypertension showed that men with the *1*1 genotype (highest alcohol intake) and those with the *1*2 genotype (intermediate alcohol intake) were 2.42 and 1.72 times more likely, respectively, to have hypertension than those with the *2*2 genotype (lowest alcohol intake). There was no association between ALDH2 genotype and hypertension among the women in these studies because they drank very little. Systolic and diastolic blood pressures showed a similar relationship to ALDH2 genotype in a second meta-analysis of relevant studies. Finally, the researchers estimated that for men the lifetime effect of drinking 1 g of alcohol a day (one unit of alcohol contains 8 g of alcohol in the UK and 14 g in the US; recommended daily limits in these countries are 3–4 and 1–2 units, respectively) would be an increase in systolic blood pressure of 0.24 mmHg.
What Do These Findings Mean?
These findings support the suggestion that alcohol has a marked effect on blood pressure and hypertension. Consequently, some cases of hypertension could be prevented by encouraging people to reduce their daily alcohol intake. Although the Mendelian randomization approach avoids most of the confounding intrinsic to observational studies, it is possible that a gene near ALDH2 that has no effect on alcohol intake affects blood pressure, since genes are often inherited in blocks. Alternatively, ALDH2 could affect blood pressure independent of alcohol intake. The possibility that ALDH2 could effect blood pressure independently of alcohol is intake made unlikely by the fact that no effect of genotype on blood pressure is seen among women who drink very little. Additional large-scale studies are needed to address these possibilities, to confirm the current finding in more people, and to improve the estimates of the effect that alcohol intake has on blood pressure.
Additional Information.
Please access these Web sites via the online version of this summary at http://dx.doi.org/10.1371/journal.pmed.0050052.
The MedlinePlus encyclopedia has a page on hypertension (in English and Spanish)
The American Heart Association provides information for patients and health professionals about hypertension
The UK Blood Pressure Association provides information for patients and health professionals on all aspects of hypertension, including information about alcohol affects blood pressure
The Explore@Bristol science center (a UK charity) provides an alcohol unit calculator and information on the effects of alcohol
The International Center for Alcohol Policies provides drinking guidelines for countries around the world
doi:10.1371/journal.pmed.0050052
PMCID: PMC2265305  PMID: 18318597

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