Individual patient data meta-analysis of self-monitoring of blood pressure (BP-SMART): a protocol.

INTRODUCTION: Self-monitoring of blood pressure is effective in reducing blood pressure in hypertension. However previous meta-analyses have shown a considerable amount of heterogeneity between studies, only part of which can be accounted for by meta-regression. This may be due to differences in design, recruited populations, intervention components or results among patient subgroups. To further investigate these differences, an individual patient data (IPD) meta-analysis of self-monitoring of blood pressure will be performed. METHODS AND ANALYSIS: We will identify randomised trials that have compared patients with hypertension who are self-monitoring blood pressure with those who are not and invite trialists to provide IPD including clinic and/or ambulatory systolic and diastolic blood pressure at baseline and all follow-up points where both intervention and control groups were measured. Other data requested will include measurement methodology, length of follow-up, cointerventions, baseline demographic (age, gender) and psychosocial factors (deprivation, quality of life), setting, intensity of self-monitoring, self-monitored blood pressure, comorbidities, lifestyle factors (weight, smoking) and presence or not of antihypertensive treatment. Data on all available patients will be included in order to take an intention-to-treat approach. A two-stage procedure for IPD meta-analysis, stratified by trial and taking into account age, sex, diabetes and baseline systolic BP will be used. Exploratory subgroup analyses will further investigate non-linear relationships between the prespecified variables. Sensitivity analyses will assess the impact of trials which have and have not provided IPD. ETHICS AND DISSEMINATION: This study does not include identifiable data. Results will be disseminated in a peer-reviewed publication and by international conference presentations. CONCLUSIONS: IPD analysis should help the understanding of which self-monitoring interventions for which patient groups are most effective in the control of blood pressure

Impact of self-monitoring of BP on the RR of uncontrolled BP at 12 months according to level of co-intervention support (15 studies).

<p>RR of uncontrolled BP adjusted for age, sex, baseline clinic BP, and history of diabetes. The trials are grouped into the 4 levels of intervention, and <i>I</i>² and <i>P</i> values are shown for each level of intervention and for the overall analysis. The effect of self-monitoring on the RR of BP at 6 and 18 months are displayed in <a href="http://www.plosmedicine.org/article/info:doi/10.1371/journal.pmed.1002389#pmed.1002389.s012" target="_blank">S5</a> and <a href="http://www.plosmedicine.org/article/info:doi/10.1371/journal.pmed.1002389#pmed.1002389.s015" target="_blank">S8</a> Figs, respectively. Wakefield study participants self-monitored for 6 months; follow-up continued to 12 months. Abbreviations: BP, blood pressure; RR, relative risk.</p

Characteristics of the included studies.

<p>Characteristics of the included studies.</p

Impact of self-monitoring of BP on clinic and ambulatory dBP at 12 months (4 studies).

<p>These 4 studies used both clinic and ambulatory BP as endpoints and so are presented in addition to the overall results in <a href="http://www.plosmedicine.org/article/info:doi/10.1371/journal.pmed.1002389#pmed.1002389.g001" target="_blank">Fig 1</a>, which are for clinic BP alone (including these studies). Change in dBP adjusted for age, sex, baseline clinic BP, history of diabetes, and level of intervention. Effect of self-monitoring on diastolic clinic and ambulatory BP at 6 months is in <a href="http://www.plosmedicine.org/article/info:doi/10.1371/journal.pmed.1002389#pmed.1002389.s017" target="_blank">S10 Fig</a>. Abbreviations: BP, blood pressure; dBP, diastolic blood pressure.</p

Impact of self-monitoring of BP on clinic sBP according to level of co-intervention support at 12 months (15 studies).

<p>Change in sBP adjusted for age, sex, baseline clinic BP, and history of diabetes. The trials are grouped into the 4 levels of intervention, and <i>I</i>² and <i>P</i> values are shown for each level of intervention and for the overall analysis. Effect of self-monitoring on clinic sBP at 6 and 18 months are shown in <a href="http://www.plosmedicine.org/article/info:doi/10.1371/journal.pmed.1002389#pmed.1002389.s010" target="_blank">S3</a> and <a href="http://www.plosmedicine.org/article/info:doi/10.1371/journal.pmed.1002389#pmed.1002389.s013" target="_blank">S6</a> Figs, respectively. Wakefield’s study participants self-monitored for 6 months; follow-up continued to 12 months. Abbreviations: BP, blood pressure; sBP, systolic blood pressure.</p

Impact of self-monitoring of BP on clinic and ambulatory sBP at 12 months (4 studies).

<p>These 4 studies used both clinic and ambulatory BP as endpoints and so are presented in addition to the overall results in <a href="http://www.plosmedicine.org/article/info:doi/10.1371/journal.pmed.1002389#pmed.1002389.g001" target="_blank">Fig 1</a>, which are for clinic BP alone (including these studies). Change in sBP adjusted for age, sex, baseline clinic BP, history of diabetes, and level of intervention. Effect of self-monitoring on systolic clinic and ambulatory BP at 6 months is in <a href="http://www.plosmedicine.org/article/info:doi/10.1371/journal.pmed.1002389#pmed.1002389.s016" target="_blank">S9 Fig</a>. Abbreviations: BP, blood pressure; sBP, systolic blood pressure.</p

Impact of self-monitoring of BP on the RR of uncontrolled BP at 12 months according to prespecified subgroups (15 studies).

<p>Obesity defined as BMI ≥ 30 kg/m². RR of uncontrolled BP at 12 months adjusted for age, sex, baseline clinic BP, level of intervention, and studies contributing patient data. Abbreviations: BMI, body mass index; BP, blood pressure; CKD, chronic kidney disease; MI, myocardial infarction; RR, risk ratio; sBP, systolic blood pressure.</p