Head-Up Tilt Testing for Detecting Orthostatic Hypotension: How Long Do We Need to Wait?

Abstract

Background: Orthostatic hypotension (OH) is a common underdiagnosed condition characterized by a fall in systolic or diastolic blood pressure (BP). There is some uncertainty about the minimum duration needed to detect OH beyond 3 min (delayed OH). We aimed to define a minimum time range for measurement of delayed OH in subjects referred to as tilt testing. Methods: A repeated measurements study Tel-Aviv Medical Center, on 692 subjects who underwent prolonged (40 min, vertical position) drug-free tilt testing. Survival curves were used to study time to an OH event; logistic regression to study factors associated with delayed OH and mixed models to study the pattern of repeated BP measures. Results: In our sample, 17% had OH within 3 min, 35% within 30 min, and 40% within 40 min. Among the 270 OH patients, 43 and 91% were identified within 3 and 30 min, respectively. Delayed OH was associated with female gender (OR = 1.95, 1.16-3.27) and age <65 years (OR = 2.17, 1.24-3.80). Older patients differed significantly from younger patients in BP pattern changes and had a higher rate of a fall in systolic BP. Conclusion: Tilt testing for 30 min identifies most cases of delayed OH in older patients, while those younger than 65 years need 10 min longer.