Should Blood Pressure Targets After Lacunar Stroke Vary by Body Size? The SPS3 Trial

Abstract

Background: It is unknown whether the physiological impact of a given blood pressure (BP) varies by body size. We explored interactions between higher vs. lower systolic BP (SBP) targets and anthropometric measures (body mass index (BMI), body surface area (BSA), height, weight) and recurrent stroke and death in the Secondary Prevention of Small Subcortical Strokes (SPS3) Trial.

Methods: Patients with recent magnetic resonance imaging-proven lacunar infarcts were randomized to 2 BP targets (130-149 mm Hg vs. <130) in a prospective, open-label, blinded end-point design. Time to outcome was evaluated with Cox proportional hazard models and compared between targets. We examined multiplicative interactions between each anthropometric measure and target and mean difference in achieved BP 1 year after randomization between BP groups by quartile. We also computed rates of recurrent stroke and death by quartiles of anthropometrics.

Results: Three thousand and twenty patients were followed over a mean of 3.7 (SD 2.0) years. Mean age was 63; 63% were male. Mean height was 167 (SD 11) cm, weight 81 (18) kg, BMI 29 (5.9) kg/m(2), and BSA 1.9 (0.25) m(2). Achieved BP at 1 year was comparable between quartiles for each anthropometric measurement. We found no consistent interactions between BP target and anthropometrics for either outcome, nor were there any significant associations between hazard of stroke or death when assessed by BMI, BSA, height, or weight.

Conclusions: We found no interactions between BP target groups and quartiles of anthropometrics for rates of stroke and death in SPS3. There is no evidence at this time supporting body size-based modifications to current BP targets for secondary prevention after lacunar stroke.

Clinical trials registration: Trial Number NCT00059306.

Keywords: BMI; BSA; blood pressure; body size; height; hypertension; lacunar stroke; prognosis; secondary prevention; weight..

Figure 1.

Effects of lower vs. higher SBP targets on risk of recurrent stroke and death according to baseline quartiles of BSA (A), BMI (B), height (C), and weight (D). Model adjusted for age, sex, race-ethnicity, region, and history of hypertension. Mean difference in SBP is between baseline and 1 year. Abbreviations: BMI, body mass index; BSA, body surface area; SBP, systolic blood pressure.

Figure 1.

Effects of lower vs. higher SBP targets on risk of recurrent stroke and death according to baseline quartiles of BSA (A), BMI (B), height (C), and weight (D). Model adjusted for age, sex, race-ethnicity, region, and history of hypertension. Mean difference in SBP is between baseline and 1 year. Abbreviations: BMI, body mass index; BSA, body surface area; SBP, systolic blood pressure.

Figure 1.

Effects of lower vs. higher SBP targets on risk of recurrent stroke and death according to baseline quartiles of BSA (A), BMI (B), height (C), and weight (D). Model adjusted for age, sex, race-ethnicity, region, and history of hypertension. Mean difference in SBP is between baseline and 1 year. Abbreviations: BMI, body mass index; BSA, body surface area; SBP, systolic blood pressure.

Figure 1.

Effects of lower vs. higher SBP targets on risk of recurrent stroke and death according to baseline quartiles of BSA (A), BMI (B), height (C), and weight (D). Model adjusted for age, sex, race-ethnicity, region, and history of hypertension. Mean difference in SBP is between baseline and 1 year. Abbreviations: BMI, body mass index; BSA, body surface area; SBP, systolic blood pressure.

Figure 2.

Adjusted hazard ratios for stroke (A) and death (B) by body size quartile. Hazard ratios are expressed using the lowest quartile (Q1) as reference. 95% confidence intervals are denoted by dotted lines. Abbreviations: BMI, body mass index; BSA, body surface area.

Figure 2.

Adjusted hazard ratios for stroke (A) and death (B) by body size quartile. Hazard ratios are expressed using the lowest quartile (Q1) as reference. 95% confidence intervals are denoted by dotted lines. Abbreviations: BMI, body mass index; BSA, body surface area.