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Self blood pressure monitoring (SBPM) can facilitate hypertension management, but determinants of SBPM are understudied. The authors examined the relationship of patient and social environment characteristics to monitor possession and frequency of SBPM in 578 male hypertensive veterans. Measures included possession of a monitor; SBPM frequency; concurrent blood pressure control; and patient demographic, clinical, and psychosocial factors. In logistic regression analyses, older age, diabetes, unemployment, and better mental health status were related to greater likelihood of monitor possession. Ordinal logistic regression showed that among patients with a monitor, having diabetes, being unemployed, and having a shorter duration of hypertension were independently related to greater frequency of SBPM. Monitor possession, but not frequency of SBPM, was related to a decreased likelihood of blood pressure control in adjusted analyses. Our results suggest that patient characteristics may influence SBPM and may represent points of leverage for intervening to increase self-monitoring.
Hypertension affects 65 million Americans1 and is a major risk factor for cardiovascular and renal disease.2 Two recent studies suggest that while rates of blood pressure (BP) control among individuals with hypertension have improved in recent years, fewer than half of all patients with hypertension have achieved target BP levels.3,4 There remains a strong incentive to understand how to improve BP control.
Self blood pressure monitoring (SBPM) at home is increasingly recognized as an important tool in hypertension management; this is noted in the latest hypertension guidelines.5 Growing enthusiasm for SBPM follows evidence that it may facilitate BP control,6–8 reduce the need for frequent office visits,7 and decrease costs of hypertension care.7 SBPM may result in improved hypertension outcomes in several ways. First, it provides documentation of the effects of medications and other lifestyle changes, which may improve patient adherence and subsequent BP control,5,9–11 particularly among patients who have difficulty remembering to take their medications.9,10 Positive results (ie, seeing BP decrease) encourage the patient to continue treatment, whereas continued high BP readings may lead to appropriate alterations in lifestyle or therapy.12 Furthermore, when therapies are unsuccessful in reducing BP, patients are more inclined to work with their physicians to alter their medical regimen sooner.13 Finally, home BP measurements may also help avoid unnecessary medication treatment due to higher office measurements resulting from the white-coat effect5 or, alternatively, may prevent providers from disregarding high clinic readings due to an assumed white-coat effect.
Despite evidence of its beneficial effects and acceptance as an important aspect of clinical care for hypertension,14,15 the factors that influence patients’ possession of a home BP monitor, and particularly the frequency with which they use monitors, are largely unknown. Some research suggests that women,16 older patients,16 and those with higher levels of education16,17 and who see physicians who involve them more in treatment decisions18 are more likely to have a monitor, although psychosocial and clinical factors remain unexamined. Furthermore, among patients who have home monitors, few studies have identified factors associated with the frequency with which they use them. Identifying possible influences on possession of a home monitor and frequency of its use could be useful in implementing interventions to increase SBPM and ultimately improve hypertension outcomes.
The goal of this study was to examine, in patients with hypertension receiving primary care through the Department of Veterans Affairs (VA) health care system, individual and social environment characteristics that were related to SBPM, including (1) possession of a home BP monitor and (2) frequency of home BP recordings among patients with a monitor. A secondary aim was to examine whether possession of a monitor or SBPM frequency was related to BP control.
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SBPM is being increasingly advocated for individuals with hypertension, yet little is known about patients’ SBPM in practice. Our investigation of male veterans with hypertension is one of few existing studies to examine the overall frequency and potential determinants of patients’ SBPM.
We found that 61% of our patient sample reported having a BP monitor at home. This is similar to the rate of 60% reported in a recent national Internet survey of patients with hypertension4 and considerably higher than the rates of 16% and 44% reported in two British clinic-based studies.17,29 Although it was unknown how participants in our study obtained their monitors, the relatively high proportion of patients with a monitor may reflect good access to monitors in the VA health system and/or encouragement from their health providers to engage in SBPM. More research is needed on the source from which patients obtain their monitors and whether health system differences and insurance coverage affect patients’ access to monitors.
We found that older age and having diabetes increased patients’ likelihood of having a home BP monitor and that individuals who had a monitor were more likely to have inadequate concurrent BP control. In other words, patients with greater risk of negative cardiovascular outcomes were more likely to have a home monitor. Our finding that unemployed individuals were more likely to have a monitor compared with employed or retired individuals is also consistent with this pattern of results, in that unemployment may be a proxy for worse functional status. Our results suggest that providers may tend to recommend SBPM for patients with risk factors for worse health outcomes, compared with patients at lower risk, or that such patients may be more likely to agree to home monitoring or initiate home monitoring on their own. In particular, patients with diabetes as well as hypertension may be more natural candidates for SBPM, in their own view as well as their providers’, because of established skills and experience with self-monitoring blood glucose levels. Regardless of the reason for these findings, it is encouraging that home monitor possession was more common among patients with greater risk, given the possible beneficial effect of SBPM on BP levels and cardiovascular outcomes. However, future interventions to increase the use of SBPM might emphasize benefits for lower-risk patients, including possible reduced need for office visits.
We also found that individuals with better mental health status were more likely to have a monitor. These results are consistent with recent findings that physicians may hesitate to intensify hypertension treatment for patients experiencing high levels of stress or psychological comorbidity.30 Such patients might also be less receptive to adding another component to their hypertension self-management regimen. More research is needed on the impact of SBPM on patients’ psychological outcomes, especially for those with preexisting psychological comorbidity.
In addition to elucidating potential influences on the likelihood that patients have a home monitor, this research fills a gap regarding the frequency with which patients who have monitors engage in SBPM. In the absence of clear guidelines as to how frequently SBPM should be performed and the absence of a significant relationship of more frequent SBPM to BP control in this sample, we are limited in our ability to make firm judgments regarding the frequency data collected in our study. However, our data suggest that among those with a home monitor, many engage in SBPM only sporadically, with 16% reporting only monthly use and 18% reporting unknown use. Furthermore, the meta-analysis showing the beneficial effect of SBPM on BP control was based on studies in which patients performed SBPM multiple times a week.6 SBPM is likely to yield fewer benefits when performed on a sporadic basis, although more research is needed on the optimal schedule of SBPM.
As with possession of a monitor, having diabetes and being unemployed were associated with greater frequency of SBPM, again suggesting that patients with greater cardiovascular risk and/or worse functional status may have greater motivation to perform SBPM consistently. In addition, having diabetes and being unemployed may facilitate more frequent SBPM from a practical standpoint. That is, those with diabetes may already engage in other disease self-monitoring tasks and may incorporate SBPM into their routine more easily, while unemployed individuals may simply experience fewer barriers related to time and competing responsibilities when trying to incorporate SBPM into their lives. We also found that patients who had been living with hypertension for a longer time were less likely to monitor more frequently, suggesting that patients who have a home monitor may become more complacent about using it regularly the longer they have the condition.
Despite a solid base of evidence that SBPM can lead to better BP control, we found that patients who had a home monitor actually had worse BP control at office visits, and among those with a monitor, more frequent SBPM was not related to BP control. These findings are likely due to limitations of our study design, namely, the cross-sectional, observational nature of our data, and should not necessarily be taken as evidence that SBPM is not effective or an important part of hypertension self-management. A more likely interpretation, as discussed above, is that physicians and patients may use SBPM more when BP is poorly controlled, as another tool to achieve BP control. Further, our reliance on BP measurements taken at office visits may have obscured the true relationship between home monitor possession and BP control. Office BP measurements might be reduced in patients without a monitor because in the absence of home BP measurements to the contrary, providers may classify patients with controlled BP as having uncontrolled BP on the basis of office assessment and perhaps (unnecessarily) intensify treatment until office measurements show that BP is controlled. However, the same treatment intensification might not occur for patients with a monitor who appear to have uncontrolled BP via office measurements but controlled BP via home measurements. Thus, the higher proportion of office BP control among those with a monitor in this study may be a result of using office measurements as our indicator of BP control, rather than a reflection of differences in rates of control among those with and without monitors.
Another limitation of our study includes an inability to generalize our findings to female patients, individuals residing in other geographic areas, or those receiving care outside of the VA health system, where cost and availability of monitors may serve as greater barriers. Also, patients who choose to participate in a randomized controlled trial relating to BP control may be more motivated to perform hypertension self-management behaviors such as SBPM or differ in other systematic ways from patients who refuse participation. More studies on the frequency and correlates of SBPM are needed, including different patient groups from different health systems. Finally, our study did not examine provider-level factors that might influence possession of a home BP monitor. A recent survey showed that 50% of patients were advised by their physicians to monitor their BP at home,4 but prior studies have also suggested that provider attitudes toward the utility of SBPM are variable.31 Future studies should examine whether these attitudes and other provider attributes influence physicians’ tendency to suggest SBPM and subsequent monitoring by patients.
Despite these limitations, this study provides some important information on the frequency with which hypertensive patients in the VA system engage in SBPM. Findings from this study suggest some patient clinical and psychosocial characteristics that may influence whether patients have access to a home monitor and use it regularly, which may prove useful to target in future interventions to increase SBPM.
Disclosure: This research was supported by the Department of Veterans Affairs, Veterans Health Administration, Health Services Research & Development Service, investigator initiative grants 20–034 (Bosworth), an established-investigator award from the American Heart Association (Bosworth), and a postdoctoral fellowship from the Veterans Health Administration’s Office of Academic Affairs (Thorpe). The views expressed in this manuscript are those of the authors and do not necessarily represent the views of the Department of Veterans Affairs, Duke University, or the University of Wisconsin.