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Self-measured blood pressure monitoring in the management of hypertension: a systematic review and meta-analysis |
Uhlig K, Patel K, Ip S, Kitsios GD, Balk EM |
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CRD summary The review concluded that self-measured blood pressure monitoring with or without additional support lowered blood pressure in adults with hypertension compared with usual care, but the effect beyond 12 months and long-term clinical benefits remained uncertain. The authors conclusions reflect the evidence presented, but given limitations of the review methods and evidence base, the conclusions seem overly strong. Authors' objectives To evaluate the effectiveness of self-measured blood pressure monitoring in adults with hypertension. Searching MEDLINE was searched from inception to February 2013. Cochrane Central Register of Controlled Trials (CENTRAL) and the Cochrane Database of Systematic Reviews were searched in the fourth quarter 2012. No language restrictions were applied. Search terms were reported. Study selection Eligible were prospective comparative studies of self-measured blood pressure with or without additional support, compared with usual care or with self-measured blood pressure monitoring with a different intervention. Studies had to have at least eight weeks follow-up. Self-measured blood pressure monitoring had to be conducted in the patient’s home by the patient or a companion. Eligible patients were adults being managed for hypertension including treated, untreated, controlled or uncontrolled. Most studies had included patients with uncomplicated hypertension and without acute disease. Most studies were conducted in North America, Australia and Western Europe. Studies were excluded if they were of patients receiving dialysis or women with gestational hypertension. Studies where monitoring was a component of disease management for heart failure or weight loss, and those that used wrist monitors were also excluded. A range of clinical outcomes were of interest including: death; cardiovascular events; patient-reported outcomes; surrogate or intermediate outcomes including blood pressure; and health care utilisation. Additional support included educational materials, web resources, telecounseling, medication management, and letters to patients. Most studies reported blood pressure as an outcome; few studies reported other outcomes. Study duration ranged from two to 24 months. Five reviewers independently selected abstracts for inclusion; it was not stated how many reviewers assessed full papers. Assessment of study quality Quality was assessed using methods by the Agency for Healthcare Research and Quality. Studies were rated as high, moderate or low quality. Methodological quality was assessed by one reviewer and checked by a second reviewer. Data extraction Data on the net change in systolic and diastolic blood pressure (mmHg) between intervention and control groups were extracted. Relative Risks were extracted for categorical blood pressure improvement. Data were grouped by intervention and comparator and by duration of follow-up. Data were extracted by one reviewer and checked by a second reviewer. Methods of synthesis Data were pooled using a random-effects model; where there was clinical heterogeneity, studies were discussed narratively. Statistical heterogeneity was assessed using the Ι² and Cochran's Q statistics. Sensitivity analyses were conducted including only high and moderate quality studies. Results of the review Fifty-two studies were included in the review with over 13,603 participants. Ten studies were graded A (high quality), 15 studies were graded B (moderate quality) and 26 were graded C (low quality); one study was ungraded as it was an abstract. Self-measured blood pressure monitoring alone versus usual care (26 comparisons): Self-measured blood pressure monitoring resulted in significantly lower blood pressure compared to usual care at six months, with a net difference for systolic blood pressure of -3.9 mmHg, and -2.4 mmHG for diastolic blood pressure (12 comparisons); the net difference was not significant at 12 months (nine comparisons). The strength of evidence was considered moderate. There was evidence of statistical heterogeneity for all the analyses. Results remained similar when analyses were restricted to high and moderate quality studies. Self-measured monitoring plus additional support versus usual care (25 comparisons): Self-measured blood pressure monitoring resulted in significantly lower blood pressure compared to usual care with net differences ranging from -2.1 to -8.3 mmHG for systolic blood pressure and from 0.0 to -4.4 mmHG for diastolic blood pressure at 12 months for five high quality studies. Low strength evidence failed to support a difference between self-measured blood pressure monitoring plus additional support versus monitoring alone or with less intense additional support (13 trials). Other outcomes were reported in the review. Authors' conclusions Self-measured blood pressure monitoring with or without additional support lowered blood pressure compared with usual care, but the effect beyond 12 months and long-term clinical benefits remained uncertain. CRD commentary The review question was clear with appropriate inclusion criteria. Some relevant databases were searched, but no apparent efforts were made to locate unpublished data which meant some data may have been missed. No language restrictions were applied which reduced the potential for language bias. Study quality was assessed and results for each study reported. Appropriate methods to reduce reviewer error and bias were reported throughout the review process. The methods of analysis appeared appropriate. The authors acknowledged a number of limitations with the evidence, which included wide variation between studies in the interventions and comparisons, blood pressure targets and management, and length of follow-up. This variation made the generalisability of the overall pooled results uncertain. Over half the studies were low quality and potentially underpowered to detect an intervention effect. Most studies had less than 12 months follow-up. It was unclear why there was a significant benefit of self-measured blood pressure at six months, but not at three or 12 months. This could be due to either the influence of small positive studies at six months that were not included in the three or 12 month analyses, the lack of power of the three and 12 month analyses compared to the six month analysis, or the substantial heterogeneity across the studies for all analyses. Therefore, it was not possible to determine whether there was any benefit of self-measured blood pressure, and if there was, whether it would be in the short-term, longer-term or both. It was also unclear as to the clinical significance of the small drop in blood pressure seen in most of the studies and analyses; the impact of such a drop may vary according to the baseline blood pressure of the population. Apart from data on blood pressure, few other outcomes were reported. The authors conclusions reflect the evidence presented but given the limitations highlighted, the conclusions seem overly strong. Implications of the review for practice and research Practice: The authors did not report any implications for practice. Research: The authors stated that further research was needed to determine the effect of self-measured blood pressure monitoring on blood pressure control beyond 12 months and the longer term benefits of self-measured blood pressure monitoring. Research should explore the effects in people stratified by patterns of home and clinic blood pressure and include subgroups such as older people, those with cardiovascular and cerebrovascular disease, diabetes mellitus, and chronic kidney disease. Funding Agency for Healthcare Research and Quality. Bibliographic details Uhlig K, Patel K, Ip S, Kitsios GD, Balk EM. Self-measured blood pressure monitoring in the management of hypertension: a systematic review and meta-analysis. Annals of Internal Medicine 2013; 159: 185-194 Other publications of related interest Uhlig K, Balk EM, Patel K, Ip S, Kitsios GD, Obadan NO, Haynes SM, Stefan M, Rao M, Kong Win Chang L, Gaylor J, Iovin RC. Self-Measured Blood Pressure Monitoring: Comparative Effectiveness. Comparative Effectiveness Review No. 45. Rockville, MD, Agency for Healthcare Research and Quality. 2012. Indexing Status Subject indexing assigned by CRD MeSH Blood Pressure; Blood Pressure Monitoring, Ambulatory; Chronic Disease; Humans; Hypertension AccessionNumber 12013046150 Date bibliographic record published 07/08/2013 Date abstract record published 09/08/2013 Record Status This is a critical abstract of a systematic review that meets the criteria for inclusion on DARE. Each critical abstract contains a brief summary of the review methods, results and conclusions followed by a detailed critical assessment on the reliability of the review and the conclusions drawn. |
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