Systolic Blood Pressure and Mortality in Community-Dwelling Older Adults: Frailty as an Effect Modifier

Abstract

Current evidence is insufficient to support different hypertension treatment targets in older adults. We evaluated whether frailty modifies the association between systolic blood pressure (SBP) and 8-year all-cause mortality in community-dwelling older adults. Longitudinal data from the ActiFE Ulm study (Activity and Function in the Elderly in Ulm; Germany) was collected. The association between SBP and mortality was analyzed using Cox proportional hazards models adjusted for age, sex, education, smoking, alcohol consumption, sleep disturbance, diastolic blood pressure, and antihypertensive medications, evaluating the presence of effect modification by frailty according to a frailty index based on the accumulation of deficits. Among 1170 participants (median age 73.9 years, 41.6% women), the prevalence of history of hypertension was 53.8% (median SBP, 144.0 mm Hg [interquartile range, 135.0–149.5], median diastolic blood pressure 78.0 mm Hg [interquartile range, 71.0–86.5]). The median follow-up time was 8.1 years, detecting 268 deaths. We identified 251 (21.5%, 114 deaths) frail participants (frailty index ≥0.2). Effect modification by frailty was detected. Among non-frail a J-shaped association was found with hazard ratio, 4.01 (95% CI, 1.13–14.28) for SBP<110 mm Hg, hazard ratio, 0.92 (95% CI, 0.53–1.59) for SBP 140–150 mm Hg, and hazard ratio, 1.98 (95% CI, 0.75–5.27) for SBP≥160 mm Hg. For frail older adults, a tendency toward lower risk among those with SBP≥130 mm Hg was observed. Our results suggest the presence of effect modification by frailty indicating a possible protective effect for elevated SBP in frail older adults with respect to all-cause mortality even after adjusting for diastolic blood pressure and antihypertensive treatment.