Clinical question: What is the relationship between timing of measurement of postural blood pressure (BP) and adverse clinical outcomes?
Background: Guidelines recommend measuring postural BP after 3 minutes of standing to avoid potentially false-positive readings obtained before that interval. In SPRINT, orthostatic hypotension (OH) determined at 1 minute was associated with higher risk of emergency department visits for OH and syncope. Whether that finding was because of the shortened interval of measurement is uncertain.
Study design: Atherosclerosis Risk in Communities Study prospective cohort.
Setting: Four U.S. communities over 2 decades.
Synopsis: In a cohort of 11,429 middle-aged patients, upright BP was measured every 25 seconds over a 5-minute interval after participants had been supine for 20 minutes. About 2-3 seconds elapsed between the end of one BP measurement and the initiation of the next. OH was defined as a 20–mm Hg drop in systolic BP. After researchers adjusted for covariates, OH at 30 seconds and 1 minute were associated with higher odds of dizziness, fracture, syncope, death, and motor vehicle crashes recorded over a median follow-up of 23 years. Measurements after 1 minute were not reliably associated with any adverse outcomes.
Bottom line: Measuring OH at 30 seconds and 1 minute reliably identifies patients at risk for associated adverse clinical outcomes.
Citation: Juraschek SP et al. Association of history of dizziness and long-term adverse outcomes with early vs. later orthostatic hypotension times in middle-aged adults..
Dr. Anderson is an associate program director in the internal medicine residency training program at the University of Colorado School of Medicine and a hospitalist at the VA Eastern Colorado Health Care System in Denver.