Self-monitoring of blood pressure in patients with multi-morbidity (BP-SMART-MM): an individual patient data meta-analysis

Problem

Self-monitoring reduces clinic blood pressure compared to usual care. A recent individual patient data analyses suggest that larger reductions can be achieved when self-monitoring is combined with more intensive co-interventions. However, the same analyses also showed that self-monitoring may not be as effective in patients with co-morbid conditions such as myocardial infarction or stroke. The aim of this study was to establish whether self-monitoring is effective at controlling blood pressure in patients with multi-morbidity. Many patients live with multimorbidty of which hypertension is the most common co-morbid condition. It is therefore important to establish which patients are most likely to benefit from self-monitoring and which co-interventions are most effective at achieving blood pressure control.

Approach

The approach: This was an individual patient data analysis of the efficacy of self-monitoring of blood pressure in hypertensive patients with multimorbidity. Individual patient data from 14 randomised trials comparing blood pressure self-monitoring to usual care for 12 months were collated. Data from all studies were pooled in a two-stage individual patient data meta-analysis using logistic regression to estimate the relative risk of blood pressure control at 12 month follow-up with self-monitoring.

Findings

Individual patient data were available for total of 6,086 patients. Self-monitoring was associated with an increased likelihood of blood pressure control at follow-up compared to usual care in patients with 1 to 3 co-morbidities (RR 1.36, 95% CI 1.13-1.64 [1 morbidity]; 1.54 95% CI 1.18-2.02 [3 co-morbidities]), but there was no evidence of benefit in those with 4 or more co-morbidities (RR 1.11, 95% CI 0.55-1.57). In patients with diabetes, stroke, CHD, CKD or obesity, self-monitoring was only associated an increased likelihood of with blood pressure control when combined with higher intensity co-interventions (diabetic patients: RR 1.06 95% CI 0.71-1.56 [low intensity intervention] vs. 1.48 95% CI 1.12-1.95 [high intensity intervention]).

Consequences

These data suggest that self-monitoring of blood pressure results in better blood pressure control in patients with multi-morbidity, except in those individuals with 4 or more co-morbid conditions. Self-monitoring appears to be effective in specific co-morbid conditions such as diabetes and stroke, but only when combined with more intensive co-interventions such as self-management, education or lifestyle counselling.