Introduction: In healthy older adults, the relationship between long-term, visit-to-visit variability in blood pressure (BP) and frailty is uncertain.

Methods: Secondary analysis of blood pressure variability (BPV) and incident frailty in >13 000 participants ≥65-70 years enrolled in the ASPirin in Reducing Events in the Elderly (ASPREE) trial and its observational follow-up (ASPREE-XT). Participants were without dementia, physical disability, or cardiovascular disease at baseline. BPV was estimated using standard deviation of mean BP from three annual visits (baseline through the second annual follow-up). Frailty was defined using Fried phenotype and a frailty deficit accumulation index (FDAI). Participants with frailty during the BPV estimation period were excluded from the main analysis. Adjusted Cox proportional hazards regression evaluated the association between BPV and incident frailty, and linear mixed models for change in frailty scores, through a maximum of 9 years of follow-up.

Results: Participants in the highest systolic BPV tertile were at higher risk of frailty compared to those in the lowest (referent) tertile of systolic BPV [Fried hazard ratio (HR) 1.17, 95% confidence interval (CI) 1.04-1.31; FDAI HR 1.18, 95% CI 1.07-1.30]. Findings were consistent when adjusted for multiple covariates and when stratified by antihypertensive use. Linear mixed models showed that higher systolic BPV was associated with increasing frailty score over time. Diastolic BPV was not consistently associated.

Conclusions: High systolic BPV, independent of mean BP, is associated with increased risk of frailty in healthy older adults. Variability of BP across visits, even in healthy older adults, can convey important risk information beyond mean BP.

Trial registration: ClinicalTrials.gov NCT01038583 and ISRCTN83772183.