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1.  Missed Opportunities to Initiate Endoscopic Evaluation for Colorectal Cancer Diagnosis 
Objectives
Delayed diagnosis of colorectal cancer (CRC) is among the most common reasons for ambulatory diagnostic malpractice claims in the United States. Our objective was to describe missed opportunities to diagnose CRC before endoscopic referral, in terms of patient characteristics, nature of clinical clues, and types of diagnostic-process breakdowns involved.
Methods
We conducted a retrospective cohort study of consecutive, newly diagnosed cases of CRC between February 1999 and June 2007 at a tertiary health-care system in Texas. Two reviewers independently evaluated the electronic record of each patient using a standardized pretested data collection instrument. Missed opportunities were defined as care episodes in which endoscopic evaluation was not initiated despite the presence of one or more clues that warrant a diagnostic workup for CRC. Predictors of missed opportunities were evaluated in logistic regression. The types of breakdowns involved in the diagnostic process were also determined and described.
Results
Of the 513 patients with CRC who met the inclusion criteria, both reviewers agreed on the presence of at least one missed opportunity in 161 patients. Among these patients there was a mean of 4.2 missed opportunities and 5.3 clues. The most common clues were suspected or confirmed iron deficiency anemia, positive fecal occult blood test, and hematochezia. The odds of a missed opportunity were increased in patients older than 75 years (odds ratio (OR) = 2.3; 95% confidence interval (CI) 1.3–4.1) or with iron deficiency anemia (OR = 2.2; 95% CI 1.3–3.6), whereas the odds of a missed opportunity were lower in patients with abnormal flexible sigmoidoscopy (OR = 0.06; 95% CI 0.01–0.51), or imaging suspicious for CRC (OR = 0.3; 95% CI 0.1–0.9). Anemia was the clue associated with the longest time to endoscopic referral (median = 393 days). Most process breakdowns occurred in the provider–patient clinical encounter and in the follow-up of patients or abnormal diagnostic test results.
Conclusions
Missed opportunities to initiate workup for CRC are common despite the presence of many clues suggestive of CRC diagnosis. Future interventions are needed to reduce the process breakdowns identified.
doi:10.1038/ajg.2009.324
PMCID: PMC2758321  PMID: 19550418
2.  Misinterpretation of the chest x ray as a factor in the delayed diagnosis of lung cancer 
Postgraduate Medical Journal  2002;78(917):158-160.
All patients in 1997 with a histologically proved diagnosis of lung cancer in Castle Hill Hospital in whom a full set of case notes and x rays could be retrieved were studied. All previous chest x rays were reviewed by a consultant chest physician and a radiologist, who were blinded to the eventual site of the lesion and the point at which a suspicious abnormality first appeared. Case notes were inspected to clarify the cause of any error. Fifty eight patients were eligible, 28 of whom had previous chest x rays. Of these 14 were found to be abnormal. A significant difference (p=0.007) in time from diagnosis to death was found between those with a missed abnormality, median (interquartile range, IQR) 105 (55–219) days and those with no previous abnormality, median (IQR) 260 (137–512) days. In the 14 in whom the diagnosis was missed the median (IQR) delay from first abnormal chest x ray to the eventual diagnostic x ray was 101 (48–339) days. A significant difference (p=0.001) was also found between the median (IQR) time from first abnormal chest x ray to start of treatment between those with missed abnormalities, 155 (115–376) days, and those with no previous abnormality on chest x ray, 51 (44–77) days. The most common reason (47%) for the diagnosis to be missed was failure of the radiologist reporting the x ray to recognise the abnormality.
It is not unusual to find previous significant radiological abnormalities in patients in whom a diagnosis of lung cancer is later made. This leads to a diagnostic delay which has a significant effect on time to initiation of treatment and palliation of symptoms, although not necessarily to eventual outcome.
doi:10.1136/pmj.78.917.158
PMCID: PMC1742288  PMID: 11884698
3.  Patient- and system-related barriers for the earlier diagnosis of colorectal cancer 
BMC Family Practice  2009;10:65.
Background
A cohort of colorectal cancer (CRC) patients represents an opportunity to study missed opportunities for earlier diagnosis. Primary objective: To study the epidemiology of diagnostic delays and failures to offer/complete CRC screening. Secondary objective: To identify system- and patient-related factors that may contribute to diagnostic delays or failures to offer/complete CRC screening.
Methods
Setting: Rural Veterans Administration (VA) Healthcare system. Participants: CRC cases diagnosed within the VA between 1/1/2000 and 3/1/2007. Data sources: progress notes, orders, and pathology, laboratory, and imaging results obtained between 1/1/1995 and 12/31/2007. Completed CRC screening was defined as a fecal occult blood test or flexible sigmoidoscopy (both within five years), or colonoscopy (within 10 years); delayed diagnosis was defined as a gap of more than six months between an abnormal test result and evidence of clinician response. A summary abstract of the antecedent clinical care for each patient was created by a certified gastroenterologist (GI), who jointly reviewed and coded the abstracts with a general internist (TW).
Results
The study population consisted of 150 CRC cases that met the inclusion criteria. The mean age was 69.04 (range 35-91); 99 (66%) were diagnosed due to symptoms; 61 cases (46%) had delays associated with system factors; of them, 57 (38% of the total) had delayed responses to abnormal findings. Fifteen of the cases (10%) had prompt symptom evaluations but received no CRC screening; no patient factors were identified as potentially contributing to the failure to screen/offer to screen. In total, 97 (65%) of the cases had missed opportunities for early diagnosis and 57 (38%) had patient factors that likely contributed to the diagnostic delay or apparent failure to screen/offer to screen.
Conclusion
Missed opportunities for earlier CRC diagnosis were frequent. Additional studies of clinical data management, focusing on following up abnormal findings, and offering/completing CRC screening, are needed.
doi:10.1186/1471-2296-10-65
PMCID: PMC2758830  PMID: 19754964
4.  Comparison of Missed Opportunities for Earlier HIV Diagnosis in 3 Geographically Proximate Emergency Departments 
Annals of emergency medicine  2011;58(1 0 1):S17-22.e1.
Objective
Differences in the prevalence of undiagnosed HIV between different types of emergency departments (EDs) are not well understood. We seek to define missed opportunities for HIV diagnosis within 3 geographically proximate EDs serving different patient populations in a single metropolitan area.
Methods
For an urban academic, an urban community, and a suburban community ED located within 10 miles of one another, we reviewed visit records for a cohort of patients who received a new diagnosis of HIV between July 1999 and June 2003. Missed opportunities for earlier HIV diagnosis were defined as ED visits in the year before diagnosis, during which there was no documented ED HIV testing offer or test. Outcomes were the number of missed opportunity visits and the number of patients with a missed opportunity for each ED. We secondarily reviewed medical records for missed opportunity encounters, using an extensive list of indications that might conceivably trigger testing.
Results
Among 276 patients with a new HIV diagnosis, 123 (44.5%) visited an ED in the year before diagnosis or received a diagnosis in the ED. The urban academic ED HIV testing program diagnosed 23 (8.3%) cases and offered testing to 24 (8.7%) patients who declined. Missed opportunities occurred during 187 visits made by 76 (27.5%) patients. These included 70 patients with 157 visits at the urban academic ED, 9 patients with 24 visits at the urban community ED, and 4 patients with 6 visits at the suburban community ED. Medical records were available for 172 of the 187 missed opportunity visits. Visits were characterized by the following potential testing indicators: HIV risk factors (58; 34%), related diagnosis indicating risk (7; 4%), AIDS-defining illness (8; 5%), physician suspicion of HIV (29; 17%), and nonspecific signs or symptoms of illness potentially consistent with HIV (126; 73%).
Conclusion
Geographically proximate EDs differ in their opportunities for earlier HIV diagnosis, but all 3 sites had missed opportunities. Many ED patients with undiagnosed HIV have potential indications for testing documented even in the absence of a dedicated risk assessment, although most of these are nonspecific signs or symptoms of illness that may not be clinically useful selection criteria.
doi:10.1016/j.annemergmed.2011.03.018
PMCID: PMC3690121  PMID: 21684399
5.  Participation in EHR based simulation improves recognition of patient safety issues 
BMC Medical Education  2014;14(1):224.
Background
Electronic health records (EHR) are becoming increasingly integrated into the clinical environment. With the rapid proliferation of EHRs, a number of studies document an increase in adverse patient safety issues due to the EHR-user interface. Because of these issues, greater attention has been placed on novel educational activities which incorporate use of the EHR. The ICU environment presents many challenges to integrating an EHR given the vast amounts of data recorded each day, which must be interpreted to deliver safe and effective care. We have used a novel EHR based simulation exercise to demonstrate that everyday users fail to recognize a majority of patient safety issues in the ICU. We now sought to determine whether participation in the simulation improves recognition of said issues.
Methods
Two ICU cases were created in our EHR simulation environment. Each case contained 14 safety issues, which differed in content but shared common themes. Residents were given 10 minutes to review a case followed by a presentation of management changes. Participants were given an immediate debriefing regarding missed issues and strategies for data gathering in the EHR. Repeated testing was performed in a cohort of subjects with the other case at least 1 week later.
Results
116 subjects have been enrolled with 25 subjects undergoing repeat testing. There was no difference between cases in recognition of patient safety issues (39.5% vs. 39.4%). Baseline performance for subjects who participated in repeat testing was no different than the cohort as a whole. For both cases, recognition of safety issues was significantly higher among repeat participants compared to first time participants. Further, individual performance improved from 39.9% to 63.6% (p = 0.0002), a result independent of the order in which the cases were employed. The degree of improvement was inversely related to baseline performance. Further, repeat participants demonstrated a higher rate of recognition of changes in vitals, misdosing of antibiotics and oversedation compared to first time participants.
Conclusion
Participation in EHR simulation improves EHR use and identification of patient safety issues.
Electronic supplementary material
The online version of this article (doi:10.1186/1472-6920-14-224) contains supplementary material, which is available to authorized users.
doi:10.1186/1472-6920-14-224
PMCID: PMC4287422  PMID: 25336294
6.  Utilizing an Electronic Health Record System to Improve Vaccination Coverage in Children 
Applied Clinical Informatics  2010;1(3):221-231.
Background
Electronic Health Records (EHR) are widely believed to improve quality of care and effectiveness of service delivery. Use of EHR to improve childhood immunization rates has not been fully explored in an ambulatory setting.
Objective
To describe a pediatric practice’s use of Electronic Health Records (EHR) in improving childhood immunization.
Methods
A multi-faceted EHR-based quality improvement initiative used electronic templates with pre-loaded immunization records, automatic diagnosis coding, and EHR alerts of missing or delayed vaccinations. An electronic patient tracking system was created to identify patients with missing vaccines. Barcode scanning technology was introduced to aid speed and accuracy of documentation of administered vaccines. Electronic reporting to a local health department immunization registry facilitated ordering of vaccines.
Results
Immunization completion rates captured in monthly patient reports showed a rise in the percentage of children receiving the recommended series of vaccination (65% to 76%) (p<0.000). Barcode technology reduced the time of immunization documentation (86 seconds to 26 seconds) (p<0.000). Use of barcode scanning showed increased accuracy of documentation of vaccine lot numbers (from 95% to 100%) (p<0.000).
Conclusion
EHR-based quality improvement interventions were successfully implemented at a community health center. EHR systems have versatility in their ability to track patients in need of vaccines, identify patients who are delayed, facilitate ordering and coding of multiple vaccines and promote interdisciplinary communication among personnel involved in the vaccination process. EHR systems can be used to improve childhood vaccination rates.
doi:10.4338/ACI-2009-12-CR-0028
PMCID: PMC3631905  PMID: 23616838
Electronic Health Records; pediatrics; childhood vaccinations; immunization registry
7.  How context affects electronic health record-based test result follow-up: a mixed-methods evaluation 
BMJ Open  2014;4(11):e005985.
Objectives
Electronic health record (EHR)-based alerts can facilitate transmission of test results to healthcare providers, helping ensure timely and appropriate follow-up. However, failure to follow-up on abnormal test results (missed test results) persists in EHR-enabled healthcare settings. We aimed to identify contextual factors associated with facility-level variation in missed test results within the Veterans Affairs (VA) health system.
Design, setting and participants
Based on a previous survey, we categorised VA facilities according to primary care providers’ (PCPs’) perceptions of low (n=20) versus high (n=20) risk of missed test results. We interviewed facility representatives to collect data on several contextual factors derived from a sociotechnical conceptual model of safe and effective EHR use. We compared these factors between facilities categorised as low and high perceived risk, adjusting for structural characteristics.
Results
Facilities with low perceived risk were significantly more likely to use specific strategies to prevent alerts from being lost to follow-up (p=0.0114). Qualitative analysis identified three high-risk scenarios for missed test results: alerts on tests ordered by trainees, alerts ‘handed off’ to another covering clinician (surrogate clinician), and alerts on patients not assigned in the EHR to a PCP. Test result management policies and procedures to address these high-risk situations varied considerably across facilities.
Conclusions
Our study identified several scenarios that pose a higher risk for missed test results in EHR-based healthcare systems. In addition to implementing provider-level strategies to prevent missed test results, healthcare organisations should consider implementing monitoring systems to track missed test results.
doi:10.1136/bmjopen-2014-005985
PMCID: PMC4244393  PMID: 25387758
Elecronic Health Records; Missed Test Results; Patient Follow-up; Social-Technical Model; Patient Safety; Diagnostic Errors
8.  Developing Software to “Track and Catch” Missed Follow-up of Abnormal Test Results in a Complex Sociotechnical Environment 
Applied Clinical Informatics  2013;4(3):359-375.
Summary
Background
Abnormal test results do not always receive timely follow-up, even when providers are notified through electronic health record (EHR)-based alerts. High workload, alert fatigue, and other demands on attention disrupt a provider’s prospective memory for tasks required to initiate follow-up. Thus, EHR-based tracking and reminding functionalities are needed to improve follow-up.
Objectives
The purpose of this study was to develop a decision-support software prototype enabling individual and system-wide tracking of abnormal test result alerts lacking follow-up, and to conduct formative evaluations, including usability testing.
Methods
We developed a working prototype software system, the Alert Watch And Response Engine (AWARE), to detect abnormal test result alerts lacking documented follow-up, and to present context-specific reminders to providers. Development and testing took place within the VA’s EHR and focused on four cancer-related abnormal test results. Design concepts emphasized mitigating the effects of high workload and alert fatigue while being minimally intrusive. We conducted a multifaceted formative evaluation of the software, addressing fit within the larger socio-technical system. Evaluations included usability testing with the prototype and interview questions about organizational and workflow factors. Participants included 23 physicians, 9 clinical information technology specialists, and 8 quality/safety managers.
Results
Evaluation results indicated that our software prototype fit within the technical environment and clinical workflow, and physicians were able to use it successfully. Quality/safety managers reported that the tool would be useful in future quality assurance activities to detect patients who lack documented follow-up. Additionally, we successfully installed the software on the local facility’s “test” EHR system, thus demonstrating technical compatibility.
Conclusion
To address the factors involved in missed test results, we developed a software prototype to account for technical, usability, organizational, and workflow needs. Our evaluation has shown the feasibility of the prototype as a means of facilitating better follow-up for cancer-related abnormal test results.
doi:10.4338/ACI-2013-04-RA-0019
PMCID: PMC3799004  PMID: 24155789
Diagnostic errors; patient safety; test results; care delays; health information technology
9.  Understanding diagnosis of lung cancer in primary care: qualitative synthesis of significant event audit reports 
Background
Most lung cancers present symptomatically, but the pathway to diagnosis in primary care can be complex and is poorly understood. Significant event audit (SEA) is a quality improvement technique widely used in UK general practice.
Aim
To gain insights into the diagnostic process for lung cancer, drawn from analysis of SEA documents.
Design and setting
Qualitative analysis of SEAs from 92 general practices in the North of England Cancer Network.
Method
Participating practices were provided with a standardised electronic template and asked to undertake a significant event audit related to the most recent diagnosis of lung cancer in the practice, even if that patient had since died. Reported accounts for 132 diagnoses were analysed using a modified framework approach.
Results
Most SEAs demonstrated timely recognition and referral. Where this had taken longer, there were often reasonable explanations, including: chest X-rays reported as normal or with benign findings; patient-mediated factors, such as delay in re-presenting or declining earlier referral; and presentation complicated by comorbidity. Some opportunities for earlier referral were also found. Lessons drawn from these events included limitations of chest X-ray as a diagnostic tool, the need for vigilance in patients with existing morbidity, and the importance of ‘safety-netting’.
Conclusion
Qualitative synthesis of SEAs offered considerable value in understanding circumstances surrounding the diagnostic process for lung cancer in primary care. The most common presentation was with cough or other symptoms indicative of infection, and it is by understanding more about these patients in particular that most can be gained.
doi:10.3399/bjgp13X660760
PMCID: PMC3529291  PMID: 23336459
cancer; early diagnosis; lung; primary health care; qualitative research
10.  What characteristics of primary care and patients are associated with early death in patients with lung cancer in the UK? 
Thorax  2014;70(2):161-168.
Background
The UK has poor lung cancer survival rates and high early mortality, compared to other countries. We aimed to identify factors associated with early death, and features of primary care that might contribute to late diagnosis.
Methods
All cases of lung cancer diagnosed between 2000 and 2013 were extracted from The Health Improvement Network database. Patients who died within 90 days of diagnosis were compared with those who survived longer. Standardised chest X-ray (CXR) and lung cancer rates were calculated for each practice.
Results
Of 20 142 people with lung cancer, those who died early consulted with primary care more frequently prediagnosis. Individual factors associated with early death were male sex (OR 1.17; 95% CI 1.10 to 1.24), current smoking (OR 1.43; 95% CI 1.28 to 1.61), increasing age (OR 1.80; 95% CI 1.62 to 1.99 for age ≥80 years compared to 65–69 years), social deprivation (OR 1.16; 95% CI 1.04 to 1.30 for Townsend quintile 5 vs 1) and rural versus urban residence (OR 1.22; 95% CI 1.06 to 1.41). CXR rates varied widely, and the odds of early death were highest in the practices which requested more CXRs. Lung cancer incidence at practice level did not affect early deaths.
Conclusions
Patients who die early from lung cancer are interacting with primary care prediagnosis, suggesting potentially missed opportunities to identify them earlier. A general increase in CXR requests may not improve survival; rather, a more timely and appropriate targeting of this investigation using risk assessment tools needs further assessment.
doi:10.1136/thoraxjnl-2014-205692
PMCID: PMC4316923  PMID: 25311471
Lung Cancer; Clinical Epidemiology
11.  The frequency of missed test results and associated treatment delays in a highly computerized health system 
BMC Family Practice  2007;8:32.
Background:
Diagnostic errors associated with the failure to follow up on abnormal diagnostic studies ("missed results") are a potential cause of treatment delay and a threat to patient safety. Few data exist concerning the frequency of missed results and associated treatment delays within the Veterans Health Administration (VA).
Objective:
The primary objective of the current study was to assess the frequency of missed results and resulting treatment delays encountered by primary care providers in VA clinics.
Methods:
An anonymous on-line survey of primary care providers was conducted as part of the health systems ongoing quality improvement programs. We collected information from providers concerning their clinical effort (e.g., number of clinic sessions, number of patient visits per session), number of patients with missed abnormal test results, and the number and types of treatment delays providers encountered during the two week period prior to administration of our survey.
Results:
The survey was completed by 106 out of 198 providers (54 percent response rate). Respondents saw and average of 86 patients per 2 week period. Providers encountered 64 patients with missed results during the two week period leading up to the study and 52 patients with treatment delays. The most common missed results included imaging studies (29 percent), clinical laboratory (22 percent), anatomic pathology (9 percent), and other (40 percent). The most common diagnostic delays were cancer (34 percent), endocrine problems (26 percent), cardiac problems (16 percent), and others (24 percent).
Conclusion:
Missed results leading to clinically important treatment delays are an important and likely underappreciated source of diagnostic error.
doi:10.1186/1471-2296-8-32
PMCID: PMC1891295  PMID: 17519017
12.  Impact of Missing Data on Analysis of Postoperative Cognitive Decline (POCD) 
Applied nursing research : ANR  2013;26(2):71-75.
Background
There are a variety of techniques to handle missing data, such as removing observations with missing data from the analyses or estimating the missing values using various imputation algorithms. Dropping subjects from standard regression models and analyzing only completers, however, may bias results from the true value of reality. Likewise, ‘last-observation-carried-forward’ may not be an appropriate technique for studies measuring a particular variable over time.
Methods
This dataset was part of a larger prospective cohort study that examined Postoperative Cognitive Decline (POCD) after surgery in older adults. Data collectors had provided the reasons for data being missing using adjectives including ‘confused,’ ‘incapable,’ ‘stuporous,’ ‘comatose,’ and ‘intubated.’ Data having these qualitative notations were re-coded as ‘incapable’ and trial scores of zero were recorded. This value of ‘0’ indicated that the patient was cognitively incapable of performing the neuropsychological test.
Results
Missing data varied by cognitive test and postoperative day. Re-coding Word List scores from missing to zero when a patient was too cognitively impaired to complete the tests improved sample size by 13.5% of Postoperative Day (POD) 1 and 12.8% on POD 2. Recoding missing data to zero for the Digit Symbol test resulted in 29.3% larger sample size on POD 1 and 22.7% on POD 2. Verbal Fluency gained 15.7% sample size with re-coding for POD 1 and 13.7% for POD 2. Re-coding of each cognitive test reduced missing data sample size to 20–32% in all cognitive tests for each day.
Discussion
Our data suggest that using a scoring system that enters a value of ‘0’ when patients are unable to perform cognitive testing did significantly increase the number of patients that met the diagnosis of postoperative cognitive decline using the criteria that were determined a priori and may lessen chances of Type II error (failure to detect a difference).
doi:10.1016/j.apnr.2012.11.001
PMCID: PMC3620895  PMID: 23290047
cognition; missing data; methods
13.  Near misses in bladder cancer - an airline safety approach to urology. 
INTRODUCTION: Traditionally, surgical audit has identified and highlighted the incidence of adverse events complicating a patient's care. The airline industry has taken this concept a step further back by identifying and studying near misses, i.e. events that have the potential to do harm. We have applied this approach to patients with known or suspected bladder cancer. PATIENTS AND METHODS: A prospective study was performed by two urology firms on all patients with known or suspected bladder cancer over a 3-week period. Patients presented to either a central (hub) hospital, or to an associated (spoke) hospital. Four stages in bladder cancer care were considered: (i) diagnostic or check flexible cystoscopy; (ii) admission to hospital prior to TURBT; (iii) peri-operative period; and (iv) first out-patient consultation. A separate proforma, comprising various aspects of management was used for each of these stages of care. If any one criterion was not met, the episode was recorded as a near miss. Near misses were classified as due to capacity limitations in the system, clerical error, equipment failure, clinical error and patient failure. RESULTS: A total of 115 completed episodes were recorded. A near miss was recorded in 65 (56.5%) of all episodes. Capacity limitations accounted for 54%, clinical error for 23%, clerical error for 16%, patient failure for 5% and equipment failure for 2% of all recorded near misses. Of particular note is that near misses relating to diagnosis were more common at the spoke hospital, delayed referral from GPs accounted for more than 25% of clinical error, diagnosis of 5 new bladder tumours was delayed and availability of upper tract imaging was a problem at all phases of patient management. CONCLUSIONS: Near misses are very common in the management of patients with bladder cancer, and their identification should provide a useful framework for identifying potential areas for improvement in patient care.
doi:10.1308/003588403322520717
PMCID: PMC1964416  PMID: 14629876
14.  Trends in missed presentations and late HIV diagnosis in a UK teaching hospital: a retrospective comparative cohort study 
Background
Late diagnosis is an important cause of HIV-related morbidity, mortality and healthcare costs in the UK and undiagnosed infection limits efforts to reduce transmission. National guidelines provide recommendations to increase HIV testing in all healthcare settings. We evaluated progress towards these recommendations by comparing missed opportunities for HIV testing and late diagnosis in two six year cohorts from North East Scotland.
Methods
We reviewed diagnostic pathways of all patients newly diagnosed with HIV referred to infectious diseases and genito-urinary medicine services between 1995 and 2000 (n = 48) and 2004 to 2009 (n = 117). Missed presentations (failure to diagnose ≤ 1 month of a clinical or non-clinical indicator for testing), late diagnosis (CD4 < 350 cells/mm3), and time to diagnosis (months from first presentation to diagnosis) were compared between cohorts using χ2 and log-rank tests. Determinants of missed presentation were explored by multivariate logistic regression. Breslow-Day tests assessed change in diagnostic performance by patient subgroup.
Results
There were significant decreases in missed presentations (33% to 17%; P = 0.02) and time to diagnosis (mean 17 months to 4 months; P = 0.005) but not in late diagnosis (56% vs. 60%; P = 0.57) between earlier and later cohorts. In the later cohort patients were significantly more likely to have acquired HIV abroad and presented with early HIV disease, and testing was more likely to be indicated by transmission risk or contact with GUM services than by clinical presentation. Missed presentation remained significantly less likely in the later cohort (OR = 0.28, 95% CI 0.11 to 0.72; P = 0.008) after adjustment for age, transmission risks and number of clinical indicators. Reductions in missed presentation were greater in patients < 40 years, of non-UK origin, living in least deprived neighbourhoods and with early disease at presentation (P < 0.05). 27% of missed presentations occurred in primary care and 46% in general secondary care.
Conclusions
While early diagnosis has improved in epidemiological risk groups, clinical indications for HIV testing continue to be missed, particularly in patients who are older, of UK origin and from more deprived communities. Increasing testing in non-specialist services is a priority.
doi:10.1186/1471-2334-12-72
PMCID: PMC3337293  PMID: 22455558
HIV; Cohort studies; Delayed diagnosis; Adult
15.  Patterns of Non-Administration of Ordered Doses of Venous Thromboembolism Prophylaxis: Implications for Novel Intervention Strategies 
PLoS ONE  2013;8(6):e66311.
Background
Recent studies have documented high rates of non-administration of ordered venous thromboembolism (VTE) prophylaxis doses. Intervention strategies that target all patients have been effective, but prohibitively resource-intensive. We aimed to identify efficient intervention strategies based on patterns of non-administration of ordered VTE prophylaxis.
Methods and Findings
In this retrospective review of electronic medication administration records, we included adult hospitalized patients who were ordered pharmacologic VTE prophylaxis with unfractionated heparin or enoxaparin over a seven-month period. The primary measure was the proportion of ordered doses of VTE prophylaxis not administered, assessed at the patient, floor, and floor type levels. Differences in non-administration rates between groups were assessed using generalized estimating equations. A total of 103,160 ordered VTE prophylaxis doses during 10,516 patient visits on twenty-nine patient floors were analyzed. Overall, 11.9% of ordered doses were not administered. Approximately 19% of patients missed at least one quarter and 8% of patients missed over one half of ordered doses. There was marked heterogeneity in non-administration rate at the floor level (range: 5–27%). Patients on medicine floors missed a significantly larger proportion (18%) of ordered doses compared to patients on other floor types (8%, Odds Ratio: 2.4, p<0.0001). However, more than half of patients received at least 86% of their ordered doses, even on the lowest performing floor. The 20% of patients who missed at least two ordered doses accounted for 80% of all missed doses.
Conclusions
A substantial proportion of ordered doses of VTE prophylaxis were not administered. The heterogeneity in non-administration rate between patients, floors, and floor types can be used to target interventions. The small proportion of patients that missed multiple ordered doses accounted for a large majority of non-administered doses. This recognition of the Pareto principle provides opportunity to efficiently target a relatively small group of patients for intervention.
doi:10.1371/journal.pone.0066311
PMCID: PMC3683023  PMID: 23799091
16.  Use and satisfaction with key functions of a common commercial electronic health record: a survey of primary care providers 
Background
Despite considerable financial incentives for adoption, there is little evidence available about providers’ use and satisfaction with key functions of electronic health records (EHRs) that meet “meaningful use” criteria.
Methods
We surveyed primary care providers (PCPs) in 11 general internal medicine and family medicine practices affiliated with 3 health systems in Texas about their use and satisfaction with performing common tasks (documentation, medication prescribing, preventive services, problem list) in the Epic EHR, a common commercial system. Most practices had greater than 5 years of experience with the Epic EHR. We used multivariate logistic regression to model predictors of being a structured documenter, defined as using electronic templates or prepopulated dot phrases to document at least two of the three note sections (history, physical, assessment and plan).
Results
146 PCPs responded (70%). The majority used free text to document the history (51%) and assessment and plan (54%) and electronic templates to document the physical exam (57%). Half of PCPs were structured documenters (55%) with family medicine specialty (adjusted OR 3.3, 95% CI, 1.4-7.8) and years since graduation (nonlinear relationship with youngest and oldest having lowest probabilities) being significant predictors. Nearly half (43%) reported spending at least one extra hour beyond each scheduled half-day clinic completing EHR documentation. Three-quarters were satisfied with documenting completion of pneumococcal vaccinations and half were satisfied with documenting cancer screening (57% for breast, 45% for colorectal, and 46% for cervical). Fewer were satisfied with reminders for overdue pneumococcal vaccination (48%) and cancer screening (38% for breast, 37% for colorectal, and 31% for cervical). While most believed the problem list was helpful (70%) and kept an up-to-date list for their patients (68%), half thought they were unreliable and inaccurate (51%).
Conclusions
Dissatisfaction with and suboptimal use of key functions of the EHR may mitigate the potential for EHR use to improve preventive health and chronic disease management. Future work should optimize use of key functions and improve providers’ time efficiency.
doi:10.1186/1472-6947-13-86
PMCID: PMC3750656  PMID: 24070335
Electronic health record (EHR); Attitude of health personnel; Attitude to computers; Primary care; Efficiency; Quality of care; Medical informatics/utilization
17.  The frequency of diagnostic errors in outpatient care: estimations from three large observational studies involving US adult populations 
BMJ Quality & Safety  2014;23(9):727-731.
Background
The frequency of outpatient diagnostic errors is challenging to determine due to varying error definitions and the need to review data across multiple providers and care settings over time. We estimated the frequency of diagnostic errors in the US adult population by synthesising data from three previous studies of clinic-based populations that used conceptually similar definitions of diagnostic error.
Methods
Data sources included two previous studies that used electronic triggers, or algorithms, to detect unusual patterns of return visits after an initial primary care visit or lack of follow-up of abnormal clinical findings related to colorectal cancer, both suggestive of diagnostic errors. A third study examined consecutive cases of lung cancer. In all three studies, diagnostic errors were confirmed through chart review and defined as missed opportunities to make a timely or correct diagnosis based on available evidence. We extrapolated the frequency of diagnostic error obtained from our studies to the US adult population, using the primary care study to estimate rates of diagnostic error for acute conditions (and exacerbations of existing conditions) and the two cancer studies to conservatively estimate rates of missed diagnosis of colorectal and lung cancer (as proxies for other serious chronic conditions).
Results
Combining estimates from the three studies yielded a rate of outpatient diagnostic errors of 5.08%, or approximately 12 million US adults every year. Based upon previous work, we estimate that about half of these errors could potentially be harmful.
Conclusions
Our population-based estimate suggests that diagnostic errors affect at least 1 in 20 US adults. This foundational evidence should encourage policymakers, healthcare organisations and researchers to start measuring and reducing diagnostic errors.
doi:10.1136/bmjqs-2013-002627
PMCID: PMC4145460  PMID: 24742777
Trigger Tools; Diagnostic Errors; Patient Safety; Chart Review Methodologies; Medical Error, Measurement/Epidemiology
18.  Electronic Health Record-Based Surveillance of Diagnostic Errors in Primary Care 
BMJ quality & safety  2011;21(2):93-100.
Background
Diagnostic errors in primary care are harmful but difficult to detect. We tested an electronic health record (EHR)-based method to detect diagnostic errors in routine primary care practice.
Methods
We conducted a retrospective study of primary care visit records “triggered” through electronic queries for possible evidence of diagnostic errors: Trigger 1: A primary care index visit followed by unplanned hospitalization within 14 days; and Trigger 2: A primary care index visit followed by ≥ 1 unscheduled visit(s) within 14 days. Control visits met neither criterion. Electronic trigger queries were applied to EHR repositories at two large healthcare systems between October 1, 2006 and September 30, 2007. Blinded physician-reviewers independently determined presence or absence of diagnostic errors in selected triggered and control visits. An error was defined as a missed opportunity to make or pursue the correct diagnosis when adequate data was available at the index visit. Disagreements were resolved by an independent third reviewer.
Results
Queries were applied to 212,165 visits. On record review, we found diagnostic errors in 141 of 674 Trigger 1-positive records (PPV=20.9%, 95% CI, 17.9%-24.0%) and 36 of 669 Trigger 2-positive records (PPV=5.4%, 95% CI, 3.7%-7.1%). The control PPV of 2.1% (95% CI, 0.1%-3.3%) was significantly lower than that of both triggers (P ≤ .002). Inter-rater reliability was modest, though higher than in comparable previous studies (κ = 0.37 [95% CI=0.31-0.44]).
Conclusions
While physician agreement on diagnostic error remains low, an EHR-facilitated surveillance methodology could be useful for gaining insight into the origin of these errors.
doi:10.1136/bmjqs-2011-000304
PMCID: PMC3680372  PMID: 21997348
diagnostic errors; primary care; patient safety; electronic health records; triggers; automated surveillance; error detection
19.  Retrospective case review of missed opportunities for primary prevention of stroke and TIA in primary care: protocol paper 
BMJ Open  2014;4(11):e006622.
Introduction
Stroke is a major health problem and transient ischaemic attack (TIA) is an important risk factor for stroke. Primary prevention of stroke and TIA will have the greatest impact on reducing the burden of these conditions. Evidence-based guidelines for stroke/TIA prevention identify individuals eligible for preventative interventions in primary care. This study will investigate: (1) the proportion of strokes/TIAs with prior missed opportunities for prevention in primary care; (2) the influence of patient characteristics on missed prevention opportunities and (3) how the proportion of missed prevention opportunities has changed over time.
Methods and analysis
A retrospective case review will identify first-ever stroke and patients with TIA between 2000 and 2013 using anonymised electronic medical records extracted from the health improvement network (THIN) database. Four categories of missed opportunities for stroke/TIA prevention will be sought: untreated high blood pressure in patients eligible for treatment (either blood pressure ≥160/100 or ≥140/90 mm Hg in patients at high cardiovascular disease (CVD) risk); patients with atrial fibrillation with high stroke risk and no anticoagulant therapy; no lipid modifying drug therapy prescribed in patients at high CVD risk or with familial hypercholesterolaemia. The proportion of patients with each missed opportunity and multiple missed opportunities will be calculated. Mixed effect logistic regression will model the relationship between demographic and patient characteristics and missed opportunities for care; practice will be included as a random effect.
Ethics and dissemination
THIN data collection was approved by the NHS South East Multi-centre Research Ethics Committee (MREC) in 2003. This study was approved by the independent scientific review committee in May 2013. Dissemination of findings has the potential to change practice, improve the quality of care provided to patients and ultimately reduce the incidence of strokes and TIAs. Findings will be published in a peer-reviewed journal and disseminated at national and international conferences.
doi:10.1136/bmjopen-2014-006622
PMCID: PMC4244480  PMID: 25387760
PRIMARY CARE; PREVENTIVE MEDICINE
20.  Outcomes of Computerized Physician Order Entry in an Electronic Health Record After Implementation in an Outpatient Oncology Setting 
Journal of Oncology Practice  2011;7(4):233-237.
EHR/CPOE systems improve completeness of medical record and chemotherapy order documentation, as well as user satisfaction with the medical record system.
Purpose:
Computerized physician order entry (CPOE) in electronic health records (EHR) has been recognized as an important tool in optimal health care provision that can reduce errors and improve safety. The objective of this study is to describe documentation completeness and user satisfaction of medical charts before and after implementation of an outpatient oncology EHR/ CPOE system in a hospital-based outpatient cancer center within three treatment sites.
Methods:
This study is a retrospective chart review of 90 patients who received one of the following regimens between 1999 and 2006: FOLFOX, AC, carboplatin + paclitaxel, ABVD, cisplatin + etoposide, R-CHOP, and clinical trials. Documentation completeness scores were assigned to each chart based on the number of documented data points found out of the total data points assessed. EHR/CPOE documentation completeness was compared with completeness of paper charts orders of the same regimens. A user satisfaction survey of the paper chart and EHR/CPOE system was conducted among the physicians, nurses, and pharmacists who worked with both systems.
Results:
The mean percentage of identified data points successfully found in the EHR/CPOE charts was 93% versus 67% in the paper charts (P < .001). Regimen complexity did not alter the number of data points found. The survey response rate was 64%, and the results showed that satisfaction was statistically significant in favor of the EHR/CPOE system.
Conclusion:
Using EHR/CPOE systems improves completeness of medical record and chemotherapy order documentation and improves user satisfaction with the medical record system. EHR/CPOE requires constant vigilance and maintenance to optimize patient safety.
doi:10.1200/JOP.2011.000261
PMCID: PMC3140445  PMID: 22043187
21.  Consequences of Missed Opportunities for HIV Testing during Pregnancy and Delayed Diagnosis for Mexican Women, Children and Male Partners 
PLoS ONE  2014;9(11):e109912.
Introduction
HIV testing during pregnancy permits prevention of vertical (mother-to-child) transmission and provides an opportunity for women living with HIV to access treatment for their own health. In 2001, Mexico’s National HIV Action Plan committed to universal offer of HIV testing to pregnant women, but in 2011, only 45.6% of women who attended antenatal care (ANC) were tested for HIV. The study objective was to document the consequences of missed opportunities for HIV testing and counseling during pregnancy and late HIV diagnosis for Mexican women living with HIV and their families.
Methods
Semi-structured-interviews with 55 women living with HIV who had had a pregnancy since 2001 were completed between 2009 and 2011. Interviews were analyzed thematically using a priori and inductive codes.
Results
Consistent with national statistics, less than half of the women living with HIV (42%) were offered HIV testing and counseling during ANC. When not diagnosed during ANC, women had multiple contacts with the health-care system due to their own and other family members’ AIDS-related complications before being diagnosed. Missed opportunities for HIV testing and counseling during antenatal care and health-care providers failure to recognize AIDS-related complications resulted in pediatric HIV infections, AIDS-related deaths of children and male partners, and HIV disease progression among women and other family members. In contrast, HIV diagnosis permitted timely access to interventions to prevent vertical HIV transmission and long-term care and treatment for women living with HIV.
Conclusions
Omissions of the offer of HIV testing and counseling in ANC and health-care providers’ failure to recognize AIDS-related complications had negative health, economic and emotional consequences. Scaling-up provider-initiated HIV testing and counseling within and beyond antenatal care and pre-service and in-service trainings on HIV and AIDS for health-care providers can hasten timely HIV diagnosis and contribute to improved individual and public health in Mexico.
doi:10.1371/journal.pone.0109912
PMCID: PMC4220915  PMID: 25372464
22.  Missing Clinical Information in NHS hospital outpatient clinics: prevalence, causes and effects on patient care 
Background
In Britain over 39,000 reports were received by the National Patient Safety Agency relating to failures in documentation in 2007 and the UK Health Services Journal estimated in 2008 that over a million hospital outpatient visits each year might take place without the full record available. Despite these high numbers, the impact of missing clinical information has not been investigated for hospital outpatients in the UK.
Studies in primary care in the USA have found 13.6% of patient consultations have missing clinical information, with this adversely affecting care in about half of cases, and in Australia 1.8% of medical errors were found to be due to the unavailability of clinical information.
Our objectives were to assess the frequency, nature and potential impact on patient care of missing clinical information in NHS hospital outpatients and to assess the principal causes. This is the first study to present such figures for the UK and the first to look at how clinicians respond, including the associated impact on patient care.
Methods
Prospective descriptive study of missing information reported by surgeons, supplemented by interviews on the causes.
Data were collected by surgeons in general, gastrointestinal, colorectal and vascular surgical clinics in three teaching hospitals across the UK for over a thousand outpatient appointments. Fifteen interviews were conducted with those involved in collating clinical information for these clinics.
The study had ethics approval (Hammersmith and Queen Charlotte's & Chelsea Research Ethics Committee), reference number (09/H0707/27). Participants involved in the interviews signed a consent form and were offered the opportunity to review and agree the transcript of their interview before analysis. No patients were involved in this research.
Results
In 15% of outpatient consultations key items of clinical information were missing. Of these patients, 32% experienced a delay or disruption to their care and 20% had a risk of harm. In over half of cases the doctor relied on the patient for the information, making a clinical decision despite the information being missing in 20% of cases. Hospital mergers, temporary staff and non-integrated IT systems were contributing factors.
Conclusions
If these findings are replicated across the NHS then almost 10 million outpatients are seen each year without key clinical information, creating over a million unnecessary appointments, and putting nearly 2 million patients at risk of harm. There is a need for a systematic, regular audit of the prevalence of missing clinical information. Only then will we know the impact on clinical decision making and patient care of new technology, service reorganisations and, crucially given the present financial climate, temporary or reduced staffing levels. Further research is needed to assess the relationship between missing clinical information and diagnostic errors; to examine the issue in primary care; and to consider the patients perspective.
doi:10.1186/1472-6963-11-114
PMCID: PMC3118108  PMID: 21605359
23.  Decreasing Missed Opportunities for HIV Testing in Primary Care through Enhanced Utilization of the Electronic Medical Record 
Journal of AIDS & clinical research  2012;Suppl 4:10.4172/2155-6113.S4-006.
Objectives
We sought to decrease “missed opportunities” for HIV testing by implementing an electronic medical record based intervention designed to increase HIV testing among previously untested men and women ages 18-64 seeking primary medical care in an urban publicly-funded health care system.
Methods
In July 2010, we implemented an electronic medical record based reminder to alert providers to the absence of an HIV test among all patients’ ages 13-64 years old. We compared the rate of missed opportunities for HIV testing among primary care patients seen during the two and a half years before the intervention with that of patients seen during the two years after the intervention was begun. A “missed opportunity” was defined as the failure of a previously untested patient to obtain HIV testing despite having made one or more primary care office visits during a specified time period.
Results
After the implementation of HIV testing reminders, first-time HIV testing increased significantly for both men and women 18-64 years old, resulting in a significant reduction in “missed opportunities.” The intervention was equally effective across different racial and ethnic groups. An increase in new HIV diagnoses after the intervention was observed, consistent with an increase in the number of individuals in the population who received testing.
Conclusions
An electronic medical record-based reminder can significantly increase HIV testing among men and women ages 18-64 who are seeking primary care services.
doi:10.4172/2155-6113.S4-006
PMCID: PMC3868368  PMID: 24363958
HIV testing reminders; Electronic medical record-based reminder; HIV diagnoses
24.  Toward an Understanding of Disengagement from HIV Treatment and Care in Sub-Saharan Africa: A Qualitative Study 
PLoS Medicine  2013;10(1):e1001369.
Norma Ware and colleagues conducted a large qualitative study among patients in HIV treatment programs in sub-Saharan Africa to investigate reasons for missed visits and provide an explanation for disengagement from care.
Background
The rollout of antiretroviral therapy in sub-Saharan Africa has brought lifesaving treatment to millions of HIV-infected individuals. Treatment is lifelong, however, and to continue to benefit, patients must remain in care. Despite this, systematic investigations of retention have repeatedly documented high rates of loss to follow-up from HIV treatment programs. This paper introduces an explanation for missed clinic visits and subsequent disengagement among patients enrolled in HIV treatment and care programs in Africa.
Methods and Findings
Eight-hundred-ninety patients enrolled in HIV treatment programs in Jos, Nigeria; Dar es Salaam, Tanzania; and Mbarara, Uganda who had extended absences from care were tracked for qualitative research interviews. Two-hundred-eighty-seven were located, and 91 took part in the study. Interview data were inductively analyzed to identify reasons for missed visits and to assemble them into a broader explanation of how missed visits may develop into disengagement. Findings reveal unintentional and intentional reasons for missing, along with reluctance to return to care following an absence. Disengagement is interpreted as a process through which missed visits and ensuing reluctance to return over time erode patients' subjective sense of connectedness to care.
Conclusions
Missed visits are inevitable over a lifelong course of HIV care. Efforts to prevent missed clinic visits combined with moves to minimize barriers to re-entry into care are more likely than either approach alone to keep missed visits from turning into long-term disengagement.
Please see later in the article for the Editors' Summary
Editors' Summary
Background
The human immunodeficiency virus (HIV) infects cells of the immune system, destroying or impairing their function. As the infection progresses, the immune system becomes weaker, and the affected person becomes more susceptible to life-threatening infections. Over the past three decades, 25 million people have died from HIV, and according to the World Health Organization, in 2011, there were roughly 34.2 million people living with HIV, over 60% of whom lived in sub-Saharan Africa. Although HIV cannot be cured, the virus can be suppressed by combination antiretroviral therapy (ART) consisting of three or more antiretroviral drugs. ART controls viral replication and strengthens the immune system, allowing the affected person to fight off infections. With ART, HIV can be managed as a chronic disease: people living with HIV can live healthy lives as long as they take antiretroviral drugs regularly for the rest of their lives.
Why Was This Study Done?
Unfortunately, poor retention in HIV programs is a huge problem: a large proportion—30%–60% in some settings in sub-Saharan Africa—of people starting ART, are lost to follow-up and stop taking treatment. Few studies have looked in depth at the reasons why people with HIV in sub-Saharan Africa miss clinic appointments or even stop coming altogether. So in this study in Tanzania, Uganda, and Nigeria, the researchers did a qualitative analysis from the patients' perspective on the reasons for missing clinic visits. Qualitative research can use information-gathering techniques, such as open-ended interviews, to develop an in-depth understanding of human behavior and the reasons behind such behavior.
What Did the Researchers Do and Find?
The researchers indentified people to interview by using “tracking lists” from HIV/AIDS care clinics in the three countries—patient tracking by clinical trackers is increasingly used as a way to contact patients who have missed clinic appointments. The researchers included people in the study who had been tracked and contacted by clinic trackers, had been absent from the clinic for three months or more, and gave consent to be re-contacted by the researchers. The researchers interviewed participants, using their local language, on several topics, including their experiences of care at the clinic and of tracking, and the circumstances of missed appointments. The detailed accounts were transcribed, and then the researchers categorized the reasons for missing appointments into intentional and unintentional reasons.
Eight-hundred-ninety patients in the three countries were tracked during the study period, but only 287 were located, of whom 91 participated in the study. Of the 91 participants, 76 were being prescribed ART, and 15 had not started treatment. The main unintentional reason for missing clinic visits was a conflicting demand on the patients' time, which was often unexpected and for complex reasons, such as caring for a dying relative, going to a funeral, or traveling to work. These reasons were often transient and changed over time. Intentional reasons were often related to dissatisfaction with the care received at the clinic, especially “the harsh treatment” they received from health workers, which typically referred to behavior perceived by patients to be rude. For example, participants reported being spoken to “roughly” or feeling that the clinic staff “didn't care.” Such behavior made patients feel hurt, humiliated, and angry, and reluctant to return to the clinic. The researchers found that, overall, disengagement from care appeared to be a process through which missed visits and subsequent reluctance to return over time eroded patients' sense of connectedness to care.
What Do These Findings Mean?
Absences from care will be inevitable over a lifetime course of treatment for HIV/AIDS. These findings indicate that absences may be unintentional as well as intentional, and that the reasons are complex and can change over time. Initial reasons for missing may disappear, leaving patients free, but reluctant, to return to care. Reasons for reluctance include shame at having been absent and the anticipation of a negative response to return from care providers. Patient education for ART initiation in sub-Saharan Africa often includes stern warnings about the lifelong commitment beginning ART represents. Paradoxically, educational efforts intended to maximize the benefits of ART for patients may be driving some away from care. Therefore, efforts to prevent missed clinic visits coupled with strategies to minimize any obstacles to coming back to care are necessary to keep patients' missed visits from turning into long-term disengagement from treatment.
Additional Information
Please access these websites via the online version of this summary at http://dx.doi.org/10.1371/journal.pmed.1001369.
This study is further discussed in a PLOS Medicine Perspective by Edward Mills
The World Health Organization has the latest data on access to ART
The US National Institute of Allergy and Infectious Diseases has more information on types of ART, and also on adherence to treatment
The US Centers for Disease Control and Prevention has some information about interventions to help improve adherence
doi:10.1371/journal.pmed.1001369
PMCID: PMC3541407  PMID: 23341753
25.  Obstructive Sleep Apnea and Risk of Cardiovascular Events and All-Cause Mortality: A Decade-Long Historical Cohort Study 
PLoS Medicine  2014;11(2):e1001599.
Tetyana Kendzerska and colleagues explore the association between physiological measures of obstructive sleep apnea other than the apnea-hypopnea index and the risk of cardiovascular events.
Please see later in the article for the Editors' Summary
Background
Obstructive sleep apnea (OSA) has been reported to be a risk factor for cardiovascular (CV) disease. Although the apnea-hypopnea index (AHI) is the most commonly used measure of OSA, other less well studied OSA-related variables may be more pathophysiologically relevant and offer better prediction. The objective of this study was to evaluate the relationship between OSA-related variables and risk of CV events.
Methods and Findings
A historical cohort study was conducted using clinical database and health administrative data. Adults referred for suspected OSA who underwent diagnostic polysomnography at the sleep laboratory at St Michael's Hospital (Toronto, Canada) between 1994 and 2010 were followed through provincial health administrative data (Ontario, Canada) until May 2011 to examine the occurrence of a composite outcome (myocardial infarction, stroke, congestive heart failure, revascularization procedures, or death from any cause). Cox regression models were used to investigate the association between baseline OSA-related variables and composite outcome controlling for traditional risk factors. The results were expressed as hazard ratios (HRs) and 95% CIs; for continuous variables, HRs compare the 75th and 25th percentiles. Over a median follow-up of 68 months, 1,172 (11.5%) of 10,149 participants experienced our composite outcome. In a fully adjusted model, other than AHI OSA-related variables were significant independent predictors: time spent with oxygen saturation <90% (9 minutes versus 0; HR = 1.50, 95% CI 1.25–1.79), sleep time (4.9 versus 6.4 hours; HR = 1.20, 95% CI 1.12–1.27), awakenings (35 versus 18; HR = 1.06, 95% CI 1.02–1.10), periodic leg movements (13 versus 0/hour; HR = 1.05, 95% CI 1.03–1.07), heart rate (70 versus 56 beats per minute [bpm]; HR = 1.28, 95% CI 1.19–1.37), and daytime sleepiness (HR = 1.13, 95% CI 1.01–1.28).The main study limitation was lack of information about continuous positive airway pressure (CPAP) adherence.
Conclusion
OSA-related factors other than AHI were shown as important predictors of composite CV outcome and should be considered in future studies and clinical practice.
Please see later in the article for the Editors' Summary
Editors' Summary
Background
Obstructive sleep apnea (OSA) is a common sleep-related breathing disorder, particularly among middle-aged and elderly people. It is characterized by apnea—a brief interruption in breathing that lasts at least 10 seconds—and hypopnea—a decrease of more than 50% in the amplitude of breathing that lasts at least 10 seconds or clear but smaller decrease in amplitude associated with either oxygen desaturation or an arousal. Patients with OSA experience numerous episodes of apnea and hypopnea during the night; severe OSA is defined as having 30 or more episodes per hour (an apnea-hypopnea index [AHI] of >30). These breathing interruptions occur when relaxation of the upper airway muscles decreases the airflow, which lowers the amount of oxygen in the blood. As a result, affected individuals frequently wake from deep sleep as they struggle to breathe. Symptoms of OSA include loud snoring and daytime sleepiness. Treatments include lifestyle changes such as losing weight (excess fat around the neck increases airway collapse) and smoking cessation. For severe OSA, doctors recommend continuous positive airway pressure (CPAP), in which a machine blows pressurized air through a face mask into the airway to keep it open.
Why Was This Study Done?
OSA can be life-threatening. Most directly, daytime sleepiness can cause accidents, but OSA is also associated with an increased risk of developing cardiovascular disease (CVD, disease that affects the heart and the circulation). To date, studies that have investigated the association between OSA and the risk of myocardial infarction (heart attack), congestive heart failure, stroke, and other CVDs have used the AHI to diagnose and categorize the severity of OSA. However, by focussing on AHI, clinicians and researchers may be missing opportunities to improve their ability to predict which patients are at the highest risk of CVD. In this historical cohort study, the researchers investigate the association between other OSA-related variables (for example, blood oxygen saturation and sleep fragmentation) and the risk of cardiovascular events and all-cause mortality (death). A historical cohort study examines the medical records of groups of individuals who have different characteristics at baseline for the subsequent occurrence of specific outcomes.
What Did the Researchers Do and Find?
The researchers used administrative data (including hospitalization records and physicians' claims for services supplied to patients) to follow up adults referred for suspected OSA who underwent diagnostic polysomnography (a sleep study) at a single Canadian hospital between 1994 and 2010. A database of the polysomnography results provided information on OSA-related variables for all the study participants. Over an average follow-up of about 6 years, 11.5% of the 10,149 participants were hospitalized for a myocardial infarction, stroke, or congestive heart failure, underwent a revascularization procedure (an intervention that restores the blood supply to an organ or tissue after CVD has blocked a blood vessel), or had died from any cause. After adjusting for multiple established risk factors for CVD such as smoking and age in Cox regression models (a statistical approach that examines associations between patient variables and outcomes), several OSA-related variables (but not AHI) were significant predictors of CVD. The strongest OSA-related predictor of cardiovascular events or all-cause mortality was total sleep time spent with oxygen saturation below 90%, which increased the risk of a cardiovascular event or death by 50%. Other statistically significant OSA-related predictors (predictors that were unlikely to be associated with the outcome through chance) of cardiovascular events or death included total sleep time, number of awakenings, frequency of periodic leg movements, heart rate, and daytime sleepiness.
What Do These Findings Mean?
These findings indicate that OSA-related factors other than AHI are important predictors of the composite outcome of a cardiovascular event or all-cause mortality. Indeed, although AHI was significantly associated with the researchers' composite outcome in an analysis that did not consider other established risk factors for CVD (“confounders”), the association became non-significant after controlling for potential confounders. The accuracy of these findings, which need to be confirmed in other settings, is likely to be limited by the lack of information available about the use of CPAP by study participants and by the lack of adjustment for some important confounders. Importantly, however, these findings suggest that OSA-related factors other than AHI should be considered as predictors of CVD in future studies and in clinical practice.
Additional Information
Please access these websites via the online version of this summary at http://dx.doi.org/10.1371/journal.pmed.1001599.
The US National Heart Lung and Blood Institute has information (including several videos) about obstructive sleep apnea (in English and Spanish), sleep studies, heart disease, and other cardiovascular diseases (some information in English and Spanish)
The UK National Health Service Choices website provides information (including personal stories) about sleep apnea and about cardiovascular disease
The not-for-profit American Sleep Apnea Association provides detailed information about sleep apnea for patients and health-care professionals, including personal stories about the condition
The MedlinePlus encyclopedia has pages on obstructive sleep apnea and on polysomnography; MedlinePlus provides links to further information and advice about obstructive sleep apnea, heart diseases, and vascular diseases (in English and Spanish)
doi:10.1371/journal.pmed.1001599
PMCID: PMC3913558  PMID: 24503600

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