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

Abstract

Background: Orthostatic hypotension (OH) based on a change from seated-to-standing blood pressure (BP) is often used interchangeably with supine-to-standing BP.

Methods: 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.

Results: 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).

Conclusion: Supine OH was more frequent, associated with orthostatic symptoms, and potentially more predictive of falls than seated OH.

Trial registration: ClinicalTrials.gov NCT02166333.

Keywords: blood pressure measurement; falls; light-headedness; orthostatic hypotension.

FIGURE 1

Unadjusted proportion (95% CI) with orthostatic hypotension at any time during the study according to seated (circle) or supine (diamond) protocols across (A) baseline age groupings: 70–74, 75–79, 80–84, and 85–97 years or greater or (B) self-reported biologic sex. Displayed is the absolute difference in proportion within each age or sex group

FIGURE 2

Mean (95% CI) (A) systolic blood pressure (SBP) and (B) diastolic blood pressure (DBP) in each position of the seated-tostanding or supine-to-standing protocols. The horizontal gray dashed line represents the mean standing blood pressure from both seated and supine protocols. Means were estimated using generalized estimating equations with a robust variance estimator. Cumulative incidence plots of the risk for recurrent fall events according to orthostatic hypotension status as a time-varying covariate identified using the (C) seated or (D) supine protocol. These plots are restricted to the population with both seated and supine protocols. Plots truncated at 750 days post-randomization