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.
Dr. Mel L. Anderson
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. JAMA Intern Med. 2017 Sep 1;177(9):1316-23.
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.