Daily low-dose aspirin and blood pressure in community-dwelling older adults

Abstract

High-quality randomized trial evidence is lacking on whether low-dose aspirin exerts significant effects on blood pressure (BP) in older adults. The authors assessed longitudinal BP changes in participants enrolled in ASPirin in Reducing Events in the Elderly (ASPREE), a randomized, placebo-controlled trial of 100 mg daily aspirin in 19 114 community-dwelling Australian and U.S. adults without cardiovascular disease (CVD), dementia, or independence-limiting physical disability. Participants' BP was recorded at baseline and annual study visits, and managed by their usual care provider. BP trajectories for aspirin versus placebo during 4.7 years of follow-up were examined for systolic and diastolic BP separately, using linear mixed models to account for between and within-individual variability in BP. Analyses by subgroups were also explored with inclusion of interaction terms in the models. The difference in mean change in systolic BP between aspirin and placebo during study follow-up was -0.03 mm Hg (95% confidence interval [CI]: -0.13, 0.07; p = .541) (aspirin minus placebo), while the mean difference for change in diastolic BP was -0.05 mm Hg (95% CI: -0.11, 0.01; p = .094). These small, non-significant differences in BP change between the aspirin and placebo groups were consistent across baseline levels of BP and antihypertensive treatment status (treated/untreated). Likewise, subgroups of age, sex, chronic kidney disease, diabetes, and frailty revealed no interaction effect between the subgroup, aspirin treatment, and time. Interval-censored Cox proportional hazards regression showed no difference in rates of incident treated hypertension between aspirin and placebo-treated participants. The authors conclude that daily low-dose aspirin does not significantly affect BP in older adults when managed by usual care.

Keywords: aspirin; blood pressure; elderly.

FIGURE 1

Population mean systolic and diastolic BPs for aspirin and placebo groups at baseline and each annual visit through the trial follow‐up period.

FIGURE 2

Linear mixed model estimates for change in blood pressure over time in subgroups: Systolic BP.