Abstract P436: Objective Physical Activity and Orthostatic Hypotension in Older Adults: The STURDY Trial

Abstract

Introduction: Orthostatic hypotension (OH) is prevalent in older adults and associated with poor health outcomes. Physical activity (PA) may attenuate the risk of OH, but evidence of the association between daily volume and patterns of objectively measured PA and OH is lacking. Hypothesis: Lower daily volume and higher fragmentation of PA are associated with greater risk of OH. Methods: We included 196 participants (age ≥70) of the Study To Understand Fall Reduction and Vitamin D in You (STURDY) trial who wore an accelerometer for 7 days at their baseline visit and completed a supine-to-standing OH assessment at 2-year follow-up. We defined OH as a 20 mm Hg drop in systolic blood pressure or 10 mm Hg drop in diastolic blood pressure 3 minutes after changing from supine to standing position. Using accelerometry, daily total activity counts (TAC; counts/day) and time spent active (mins/day) were used to measure volume of daily PA. Active-to-sedentary transition probability (ASTP) was calculated as the reciprocal of the average PA bout duration to measure PA fragmentation. Multivariable robust Poisson regression estimated the risk ratio between baseline PA and OH after 2-years of follow up. Results: Among 196 participants, 12.2% of participants had OH after 2-years of follow up; 62.2% were male, and mean baseline age was 76.4 (SD=5.2). In this prospective analyses, lower daily activity (lowest vs highest tertile of TAC: RR = 6.49, 95% CI: 2.15-19.58; lowest vs highest tertile of time spent active: RR= 4.30, 95% CI:1.55-11.92) and higher fragmentation (highest vs lowest tertile of ASTP: RR = 5.36, 95% CI: 1.57-18.34) of PA were associated with higher risk of OH after 2 years (Figure) . Conclusions: Both lower daily activity volume and higher fragmentation of PA were associated with increased risk of OH in older adults over follow-up. Longitudinal studies to assess whether changes in PA volume or fragmentation alter the risk of OH should be explored.