Comparison of supine and seated orthostatic hypotension assessments and their association with falls and orthostatic symptoms

Orthostatic hypotension (OH) based on a change from seated-to-standing blood pressure (BP) is often used interchangeably with supine-to-standing BP.The Study to Understand Fall Reduction and Vitamin D in You (STURDY) was a randomized trial of vitamin D3 supplementation and fall in adults aged ≥70 years at high risk of falls. OH was defined as a drop in systolic or diastolic BP of at least 20 or 10 mmHg, measured at pre-randomization, 3-, 12-, and 24-month visits with each of 2 protocols: seated-to-standing and supine-to-standing. Participants were asked about orthostatic symptoms, and falls were ascertained via daily fall calendar, ad hoc reporting, and scheduled interviews.Among 534 participants with 993 paired supine and seated assessments (mean age 76 ± 5 years, 42% women, 18% Black), mean baseline BP was 130 ± 19/68 ± 11 mmHg; 62% had a history of high BP or hypertension. Mean BP increased 3.5 (SE, 0.4)/2.6 (SE, 0.2) mmHg from sitting to standing, but decreased with supine to standing (mean change: -3.7 [SE, 0.5]/-0.8 [SE, 0.3] mmHg; P-value 0.001). OH was detected in 2.1% (SE, 0.5) of seated versus 15.0% (SE, 1.4) of supine assessments (P 0.001). While supine and seated OH were not associated with falls (HR: 1.55 [0.95, 2.52] vs 0.69 [0.30, 1.58]), supine systolic OH was associated with higher fall risk (HR: 1.77 [1.02, 3.05]). Supine OH was associated with self-reported fainting, blacking out, seeing spots and room spinning in the prior month (P-values 0.03), while sitting OH was not associated with any symptoms (P-values ≥ 0.40).Supine OH was more frequent, associated with orthostatic symptoms, and potentially more predictive of falls than seated OH.