Trials to improve blood pressure through adherence to antihypertensives in stroke/TIA: systematic review and meta-analysis

Abstract

Background: The purpose of this study was to determine whether interventions including components to improve adherence to antihypertensive medications in patients after stroke/transient ischemic attack (TIA) improve adherence and blood pressure control.

Methods and results: We searched MEDLINE, EMBASE, CINAHL, BNI, PsycINFO, and article reference lists to October 2012. Search terms included stroke/TIA, adherence/prevention, hypertension, and randomized controlled trial (RCT). Inclusion criteria were participants with stroke/TIA; interventions including a component to improve adherence to antihypertensive medications; and outcomes including blood pressure, antihypertensive adherence, or both. Two reviewers independently assessed studies to determine eligibility, validity, and quality. Seven RCTs were eligible (n=1591). Methodological quality varied. All trials tested multifactorial interventions. None targeted medication adherence alone. Six trials measured blood pressure and 3 adherence. Meta-analysis of 6 trials showed that multifactorial programs were associated with improved blood pressure control. The difference between intervention versus control in mean improvement in systolic blood pressure was -5.3 mm Hg (95% CI, -10.2 to -0.4 mm Hg, P=0.035; I(2)=67% [21% to 86%]) and in diastolic blood pressure was -2.5 mm Hg (-5.0 to -0.1 mm Hg, P=0.046; I(2)=47% [0% to 79%]). There was no effect on medication adherence where measured.

Conclusions: Multifactorial interventions including a component to improve medication adherence can lower blood pressure after stroke/TIA. However, it is not possible to say whether or not this is achieved through better medication adherence. Trials are needed of well-characterized interventions to improve medication adherence and clinical outcomes with measurement along the hypothesized causal pathway.

Keywords: blood pressure; hypertension; prevention; stroke.

Figure 1.

Study flow. TIA indicates transient ischemic attack.

Figure 2.

Representation of interventions from the 7 trials included in the review. See label on top right for explanation. Sizes correlated with percentge of involvement. *Significant blood pressure improvement in the intervention group. m Indicates months; TIA, transient ischemic attack; HTN, hypertension; f/u, follow‐up; GP, general practitioner.

Figure 3.

Meta‐analysis of effect of interventions on systolic blood pressure (A) and diastolic blood pressure (B). SD indicates standard deviation; CI, confidence interval.

Figure 4.

Sensitivity analysis to explore the impact of excluding: A, relatively small studies (with <50 participants per randomization group); B, the study considered at high risk of bias; C, studies that did not measure adherence; D, studies that did not properly describe the adherence component of the intervention. SBP indicates systolic blood pressure; DBP, diastolic blood pressure.