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This paper reports the results of a clinical investigation to determine the sustainability of intervention effects to lower blood pressure (BP) that were obtained through a short term education via home tele-monitoring of BP and regular counseling by bilingual nurses over one year. A total of 359 middle-aged (40–64 yrs) Korean immigrants completed a 15-month intervention that consisted of 6-week behavioral education followed by home tele–monitoring of BP and bilingual nurse telephone counseling for 12 months. The final analysis revealed a sharp increase in BP control rates sustained for over 12 months. At baseline, only 30% of the sample achieved BP control (< 140/90 mmHg). After the initial education period (approximately 3 months), 73.3% of the participants had controlled BP levels. The levels of control were maintained and continuously improved over a 12 month follow-up period (83.2%, p < 0.001). These findings suggest that BP monitoring and tailored counseling are both useful tools to sustain or improve short term intervention effects.
High blood pressure (HBP) remains a major public health concern both in the US and worldwide. According to a recent report by the Institute of Medicine 1, the health and economic burden of cardiovascular disease (CVD) and its risk factors, such as hypertension, has a major impact not only in developed countries but also in many low and middle income countries. There is a great need for crystallized lessons learned from developed countries such as the US in the management of hypertension that can be essential for implementing effective treatment strategies for individuals affected by such emerging epidemics such as hypertension and CVD worldwide.
Unfortunately, the report card for addressing the management of HBP in population levels for developed countries including the US is sub-optimal. Despite abundant knowledge, treatment options, and well established clinical guidelines for hypertension, only 24–29 % of people affected by the condition actually achieve the optimal levels of blood pressure (BP). 2 Moreover, the disease burden of HBP is known to disproportionately affect certain groups of individuals especially those that are socially disadvantaged. Certain ethnic minority groups such as African Americans and Korean Americans have been reported to have a higher prevalence of uncontrolled hypertension when compared to individuals from dominant cultural groups. 3–7
Managing chronic health conditions such as HBP requires providing evidence based pharmacological treatment and effective education of critical behaviors to promote healthy individual choices and appropriate self-care. The importance of promoting self care in managing HBP is underscored by the overall low control rate of HBP despite the overwhelming evidence for the effectiveness of pharmacological interventions in reducing BP both in the US and other developed countries.
Lifestyle modification or psychobehavioral education interventions of high blood pressure have varying degree of successes. 8–15 While most of these interventions have yielded successful outcomes in a relatively short amount of time (8 weeks to 6 months), the sustainability of those intervention outcomes or long term effects are questionable as many studies are only measured by short term outcomes.
Given that the nature of managing BP control is considered a life time endeavor, it is important to find effective ways to improve both self-care skills and motivations for individuals with hypertension over the course of their lifetime. Unfortunately, there has been little discussion about systematic ways to improve and maintain self care skills after critical knowledge and skills are obtained through a lifestyle modification education program with the goal of achieving and maintaining optimal BP as well as preventing complications.
A significant omission from the current literature includes ways of incorporating ever increasing health technology as a tool for motivating and improving self care behaviors in long term settings. Recently, intervention studies examining the effects of self-BP monitoring suggested that self monitoring of BP is associated with moderate BP reduction independent of other factors. 16–19 These findings are worth further exploring to see the effects of self monitoring as a potential means of sustaining positive effects through effective education or behavioral lifestyle modification interventions provided in community samples.
In light of these considerations, we designed a study that examines the sustainability of a community based lifestyle modification educational program using telephone transmitted self BP monitoring technology and nurse-led counseling done in a sample with HBP. In this paper, we present a pattern of sustainability of the individual’s knowledge self care skills and BP control one year after the group of people achieve the positive effect on these outcomes through short term education.
The Self-Help Intervention Program for HBP care (SHIP-HBP) was a community-based clinical trial designed to test the effects of a culturally tailored behavioral intervention in KAs residing in the Baltimore-Washington Metropolitan area. The SHIP-HBP combined a 6-week psycho-behavioral education with 12 months of BP self-monitoring and telephone counseling conducted by bilingual nurses. Details about the study design were reported elsewhere. 20 To be brief, the study employed a 2×2 factorial design with two key factors: a mode of education (i.e., in-class vs. mail) and intensity of telephone counseling (i.e., more intensive, bi-weekly counseling vs. less intensive, monthly counseling). Participants in both counseling groups used BP self-monitoring throughout the 12-month counseling period (Figure 1). Study outcomes included systolic and diastolic BP levels and several psychosocial variables that were collected at: baseline, 3, 9, and 15 months (except for BP measurements made via self-monitoring at home). The positive BP changes in study outcomes at the 3-month follow-up were also reported. 20 In the present paper, we are reporting the study outcomes collected at 3 months through 15 months during which the telephone counseling was offered.
Eligibility criteria for the SHIP-HBP trial included: 40 to 64 years of age; systolic BP (SBP) ≥ 140 mm Hg and/or diastolic BP (DBP) ≥ 90 mm Hg on two separate occasions or being on antihypertensive medication; and self-identification as a KA. At baseline, 445 eligible KAs were recruited through ethnic churches, grocery stores, and ethnic newspaper advertisements. Over the course of the clinical trial, 85 participants dropped out, resulting in 359 KAs at the 15-month follow-up. There were no significant differences in sociodemographic characteristics between those who remained in the study and those who dropped out.
Study procedures were approved by the Institutional Review Board, and every participant provided written informed consent. During the baseline evaluation, trained bilingual nurses obtained three BP measurements at 1-min intervals, while demographic and psychosocial variables were measured via self-report. Participants were then assigned to either the in-class or the mail education groups to receive HBP-related education for a 6 week period. Upon completion of the 6-week education, participants were given a BP monitor (A&D UA-767) equipped with a tele-transmission system along with instructions. They were asked to measure their BP at home and transmit the BP data via phone over the following 6 weeks of the test period, during which it was made certain that all participants were able to measure and transmit their BP readings.
At 3 months (i.e., at the end of the 6-week test period), the KAs were randomly assigned to either the more intensive counseling (MC) or less intensive telephone counseling (LC) groups. The MI group received bi-weekly telephone counseling, while the LI group received less frequent, monthly counseling by a trained bilingual nurse for 12 months. Trained nurse counselors made the phone calls from a private office at a local community center. As a safety measure, nurses called the participants regardless of the counseling schedule if the transmitted BP readings were 160/100 mm Hg or higher and contacted a consulting physician on the study team. When the BP readings were 180/110 mm Hg or higher, nurses either called the patient immediately to ask him/her to visit a nearby emergency room or called his/her physician. Nurses followed these up with off-schedule phone calls and then with an additional call within a week for updates.
During the counseling period, participants were instructed to measure their BP three times both upon waking (AM reading) as well as before retiring to bed at night (PM reading). The participants were asked to perform both sets of triplicate measurements two or more times a week. The transmission device automatically saved up to 200 BP measurements. Nevertheless, in order to facilitate timely screening of abnormal BP readings and feedback, participants were asked to send their measurements via telephone at least once a week. Transmitted BP data was used to generate BP reports, which showed the time and frequency of both the BP measurements and BP readings. BP reports were made available to both the participant as well as the nurse counselor throughout the 12-month counseling period.
During the 12-month counseling period, BP was measured at home by participants using the A&D UA-767 (A&D Company, Ltd, Tokyo, Japan), which is a fully automatic device using the oscillometric method. Given varying numbers of BP measurements for each participant, it was determined that the bi-weekly means of SBP and DBP measurements be used to derive BP data for the current investigation (see details about compliance with home BP monitoring). In accordance with the guidelines laid out in the seventh report of the Joint National Committee on Prevention, Detection, and Treatment and Control of High Blood Pressure, BP control was defined as home-measured BP < 135/85 mm Hg (130/85 mm Hg for patients with diabetes).
Other assessments included sociodemographic characteristics, insurance status, and medical history measured at baseline through the study questionnaire. In addition, psychosocial outcome variables were measured at baseline, 3, 9, and 15 month follow-ups. Specifically, HBP knowledge was assessed using 12 items developed by the National HBP Education Program of the National Heart Lung Blood Institute as well as by using 14 items generated by the investigative team based on the literature review. The HBP knowledge instrument has previously been used in KAs. HBP beliefs were assessed using a 12-item questionnaire. The questionnaire asked participants to indicate whether they believed certain behavioral factors could help lower their BP (i.e., smoking, stress, weight, alcohol, salt, medication, coffee, diet, cholesterol, and exercise) and what the most important factors were in controlling their BPs. HBP self-efficacy was measured using a scale adapted from the HBP belief scale. The modified scale used 4-point Likert type items asking how confident the person was in managing HBP in 11 different areas such as reducing salt intake, taking HBP medicines, or eating fatty foods less frequently. Higher scores indicated higher levels of self-efficacy in the management of HBP. Depression was measured using the Kim Depression Scale for Korean Americans (KDSKA). The KDSKA contains 21 items assessing depressive symptoms in the following four categories: emotional, cognitive, behavioral, and somatic. Each item is presented on a 4-point Likert-type scale as a declarative sentence related to one symptom of depression from the previous one-week period. Higher scores represented more depressive symptoms. Finally, medication adherence was measured through the medication subscale from the Hill-Bone Compliance Scale. The scale consisted of nine items on a 4-point Likert-type scale that measured the self-reported degree of adherence to HBP medication regimen. Higher scores indicated lower adherence.
Only participants who self-reported at least one BP measurement were included in the statistical analysis (N=359). Two blood pressure outcomes (mean SBP and mean DBP measured bi-weekly) and five psycho-social outcomes (the mean scores of the HBP knowledge, HBP beliefs, HBP self-efficacy, KDSKA, and Hill-Bone Compliance Scale instruments measured at three follow-up assessments) were modeled using mixed-effects models to examine the rate of change over time, differences between intervention groups, and differences in the rates of change between intervention groups for each outcome. At each follow-up, only those subjects completing at least six of the nine items on the Hill-Bone Compliance Scale and taking BP medication were included in the adherence model (N=240). Each person could report up to 34 biweekly BP measurements during follow-up; in total, 5408 biweekly BP observations were collected from 352 participants. The average number of measurements per participant was 15.4.
Nonlinear rates of change were considered for the BP models; however, the more parsimonious linear model was deemed sufficient via visual examination of the model diagnostics. Mixed-effects models were implemented to account for the correlation induced by repeated measures (section 3.1 in Rabe-Hesketh and Skrondal, 2008; Gardiner et al., 2009). The models were adjusted for age, sex, marital status, education, work status, health insurance status, years of residence in the US, BP medication status, family history of high BP, and years of high BP. All modeling was done in R version 2.8.1 (R Development Core Team, 2008).
After the initial education period (approximately 3 months), there was no statistically significant difference in the variables between groups (Table 1). The proportion of females was slightly more than that of males (47.1% male and 52.9% female) and the majority of participants (94.4%) were married. More than a half (55.2%) of the participants had at least graduated college and 56.8% of all the participants held full-time jobs. Less than 40 % of the participants had medical insurance (39.8%) and more than 40% of the patients were not on any BP medication (42.6%). 74.7% of the participants had one or more family members suffering from HBP and the percent for having other diseases, such as diabetes and hyper lipidemia, was 14.8%. The mean age was 51.9 years (range, 38–64 years), and mean period that the participants had suffered from HBP was 4.2 years.
In the analysis of BP changes using repeated measures of the mixed effect model, on average, we found a decrease of 0.13 mm Hg (95% CI=0.06, 0.20) over every two week period in the mean SBP of a typical individual in the group receiving the less intensive intervention, when controlling for age, gender, marital status, education, employment status, insurance coverage, years of high blood pressure, medications, family history, and co morbidities. We observed an average decrease of 0.15 mm Hg (95% CI=0.21, 0.08) over each two week period in the mean SBP of a typical individual in the group receiving the more intensive intervention, when controlling for all other covariates.
Similarly, we found an average decrease of 0.07 mm Hg (95% CI=0.02, 0.11) over every two week period in the mean DBP of a typical individual in the LI group when controlling for age, gender, marital status, education, employment status, insurance coverage, years of high blood pressure, medications, family history, and co- morbidities. We observed an average decrease of 0.11 mm Hg (95% CI=0.16, 0.07) over every two week period in the mean DBP of a typical individual in the MI group, when controlling for all other covariates.
In order to illustrate these BP changes in more simplistic manner, we have compared baseline BP with follow up BP using the estimated BP value based on the most typical individual in each group controlling all other covariates (e.g., age, marital status, education, employment, insurance, currently on BP medication,).
The baseline BP of the MI group was 145.5/91.5. After the class intervention, a typical individual in the MI group achieved a level of well-controlled BP at 3 months (133.03/82.37). This trend was also maintained at both the 6 month (131.15/81.69) and at 9 month (130.26/81.01) follow- up time points. Similarly, the baseline BP of the LI group was 142.1/90.91 and a typical individual from the group achieved a BP measurement of 133.28/82.85 at the 3 month follow-up time point. The BP of a typical individual from the LI group at the follow-up time points were 132.53/82.45 and 131.77/82.05 at 6 months and 9 months, respectively.
In order to assess the sustainability of maintaining controlled BP through our intervention strategies (counseling with Tele-transmitted Home BP monitoring), after these individuals achieved initial BP control, the proportion of individuals with controlled BP during the one year period were monitored on a monthly basis (Figure 2). The proportion of controlled BP for both groups (MC and LC) were well maintained (range 57.13% to 69.87%) over the one year period. In fact, the proportion of control rates of both groups continually improved whereas the MI group showed greater control rate (68.87% at 15 month) than LC group (65.22%). The control rate of the MC group at 3 month follow-up and the control rate of the LC group was 57.13 and 57.71%, respectively.
We used repeated measures of mixed linear models to test the long term effects of the counseling intervention on relevant psychological variables and self help skills.
Depression scores for both counseling groups decreased over time. There are no statistically significant differences between groups which indicats that the less frequent counseling was as effective as the more frequent counseling group. On average, we observed a decrease of 0.028 (95% CI = 0.051, 0.005) in the mean depression score of participants in the LC group and an average decrease of 0.027 (95% CI= 0.003, 0.051) in the MC group over every 3 month period when controlling for age, gender, marital status, education, employment status, insurance coverage, years of high blood pressure, medications, family history, and comorbidities (Table 4).
The evaluation of self efficacy using a repeated measure of the mixed effect model found that the perceived self efficacy was slightly increased over time for those participants who received more frequent counseling intervention (MC group) whereas it was slightly decreased in the LC group. We observed an average increase of 0.003 (95% CI= 0.017 decrease, 0.022 increase) in the mean self-efficacy score for participants in the MC group and a decrease of 0.004 (95% CI = 0.023 decrease, 0.015 increase) over every 3 month period when controlling for age, gender, marital status, education, employment status, insurance coverage, years of high blood pressure, medications, family history, and co morbidities.
The results of a mixed linear model using HBP knowledge as an outcome variable demonstrated that as a group, the participants retained the knowledge that they obtained via the structured education program over a year ago. In fact, both groups with different frequencies of counseling demonstrated small increases in the HBP knowledge questionnaire. We observed an increase of 0.014 (95% CI = 0.007, 0.021) in the mean knowledge score of participants in the LI group and an average increase of 0.014 (95% CI= 0.007, 0.020) in MC group over every 3 month period when controlling for age, gender, marital status, education, employment status, insurance coverage, years of high blood pressure, medications, family history, and comorbidities. (Table 4)
Similarly, the mixed effect model using HBP related health beliefs also demonstrated small increases over time in both groups: we observed a mean score increase of 0.016 (95% CI = 0.003 decrease, 0.035 increase) in the LC group and an average increase of 0.018 (95% CI= 0.002 decrease, 0.037 increase) in the MC group over every 3 month period when controlling for age, gender, marital status, education, employment status, insurance coverage, years of high blood pressure, medications, family history, and comorbidities.
Participants in both groups showed improvement in their adherence levels on HBP treatment recommendations including HBP medication taking, low salt diet and appointment keeping behavior with his/her doctor. On average, we observed a decrease of 0.046 (95% CI = 0.024, 0.069) in the mean non-adherence score of participants in the LC group and an average decrease of 0.028 (95% CI= 0.006, 0.050) in the MC group over every 3 month period when controlling for age, gender, marital status, education, employment status, insurance coverage, years of high blood pressure, medications, family history, and comorbidities.
The present study indicated that individualized counseling by bilingual nurses based on tele-transmitted monitoring of home BP was effective in sustaining BP control achieved through a series of group HBP education over 12 months in hypertensive Korean Americans. Moreover, the findings of this study suggested that counseling strategy accompanied by home BP monitoring was successful for further improving BP control. While the exact dose response association was not quantified, the participants in the more counseled group improved their BP and psychosocial outcomes more than participants in the less counseled group. This pattern of steady improvement in BP outcomes is clinically meaningful as maintaining optimal BP over time directly leads to declines in stroke and coronary artery disease incidence and mortality. 21, 22
The favorable results in the improvement of psychosocial outcomes such as the decrease of depressive symptoms are also noteworthy. Depression was known as an important correlate of critical self care behavior in HBP, such as adherence to treatment recommendations and self efficacy. 23
Another encouraging outcome of this counseling strategy that was illustrated in this evaluation was the retainment of HBP knowledge that was obtained by participants after a 6 week HBP cluster education. As reported in our previous paper that described our 3 month follow up results that immediately followed the cluster education, an individual’s knowledge of HBP was significantly increased after the education. 20 The present study demonstrated that the level of improved HBP knowledge was sustained after 15 months of intervention (from the point of baseline measurement). Based on this result, it is safe to conclude that regular feedback from a nurse counselor can act as a continuing booster intervention to maintain the participants’ knowledge of HBP. Non-adherence was also shown to improve at 24 months, which included HBP medical treatment, low sodium diet, and appointment-keeping behavior with his/her doctor. However, we could not find a dose-effect relationship between telephone counseling intensity and self-care behavior despite both groups showing improvement in health behaviors. 24
Home BP monitoring has been well investigated as an intervention for improving BP control.25–28 BP measurement seems to improve BP recognition, which may lead to improved BP medication adherence and better BP control. Because both groups (more intensive counseling group vs. less intensive counseling group) received tele-transmitted BP monitoring, we could not make any inference on the independent effect of home BP monitoring on BP outcomes.
The sustaining pattern of significant improvements and of BP outcomes for both groups over a relatively long period time, however, highlights the potential efficacy of the combined strategy with counseling and home BP monitoring in maintaining optimal BP levels for a long period of time. It seems that the self monitoring of BP provides a certain level of biofeedback 29, which also helps to motivate the individual towards staying with desirable behaviors for maintaining or improving BP outcomes such as medication adherence and subscribing to a healthy lifestyle. 30
While our study is the first study of its kind that tests the efficacy of a combined strategy (counseling and home BP monitoring) in producing a long term sustainability of optimal BP outcomes, positive short term outcomes of a tailored telephone counseling by a nurse have been reported in the literature. 31–35 As with other studies, our individual counseling includes problem-solving in regards to BP measurement, medical treatment, and maintaining a healthy lifestyle (e.g., diet, exercise, weight control, smoking, and alcohol consumption. A unique characteristic of our counseling protocol was that all counseling was conducted by trained bilingual nurses. Given that the participants of this study were first generation immigrants facing significant language barriers when using mainstream resources, the culturally tailored education messages delivered and discussed with bilingual nurses were well received by the participants. The detailed information regarding our counseling protocol was reported elsewhere. 24
The limitations of our study are as follows: First, because of the lack of a true control group, our inferences were strictly based on relative assessment rather than an absolute comparison between the intervention and control group. In addition, because we did not use a factorial design that would have helped to partition the independent effect of each component of our intervention, we could not come to any precise conclusions on which parts of the strategy (counseling vs. home BP monitoring) were the most important for yielding desirable long term BP outcomes.
Despite these limitations, the findings of this study suggest that the combined strategy of counseling and home BP monitoring is an effective strategy for improving long term BP outcome for the individuals. In particular, the strategies we have used in this study can inform researchers and clinicians wanting to find community based evidence materials that deliver high quality, equitable care for increasingly diverse patient populations.
This research was supported by a grant from the Agency for Healthcare Research and Quality (R01 HS13160, Clinical Trials Registry NCT00473681) and the Johns Hopkins University School of Nursing Center for Excellence in Promoting Cardiovascular Health for Vulnerable Populations (funded by National Institute of Nursing Research P30 NR011409).