Timing of BP Measurements in Orthostatic Hypotension Linked to Adverse Effects

Orthostatic hypotension (OH) measurements taken within 1 minute after rising from supine to standing position had the strongest associations with adverse outcomes, according to a study published in JAMA Internal Medicine.

Stephen P. Juraschek, MD, PhD, and fellow researchers from the Department of Medicine at the Johns Hopkins School of Medicine in Baltimore, Maryland, conducted a prospective cohort study to compare early vs later OH measurements to dizziness rates and adverse outcomes.

The researchers formed a study cohort from the Atherosclerosis Risk in Communities (ARIC) Study of 15,792 adults aged 45 to 64 years who were originally enrolled from 1987 to 1989. The cohort was then limited to 11,429 participants (mean age, 54 years at baseline visit). OH was defined as a drop in blood pressure (BP): a systolic BP (SBP) ≥20 mm Hg or a diastolic BP (DBP) ≥10 mm Hg.

At the baseline visit, supine SBP and DBP were measured using a Dinamap 1846 SX oscillometric device after participants had been lying down for 20 minutes. Before standing, participants were asked if they usually experience dizziness when standing up, and a yes or no answer was recorded. Participants were than instructed to stand up quickly and in 1 smooth motion. A total of 5 BP measurements were recorded within 2 minutes on standing.

The researchers found that 10% of the study population reported a history of dizziness on standing at the baseline visit. The mean (SD) times of measurements 1 through 5 after standing were 28.0 seconds (5.4), 52.6 seconds (7.5), 76.4 seconds (9.1), 100 seconds (10.4), and 116.0 seconds (4.6), respectively.

The second measurement was found to have the largest reduction in SBP from supine to standing, as well as the smallest increase in DBP, at −1.2 (12.4) mm Hg and 2.3 (6.3) mm Hg, respectively. Measurement 1 recorded the highest proportion of dizziness in participants, at 13.5% (95% CI, 11.0%-16.1%).

During a follow-up period of 23 years, researchers recorded 2089 falls (18.3% of events), 3104 fractures (27.2%), 2326 syncopal episodes (20.4%), 426 motor vehicle crashes (3.7%), and 4119 deaths (36.0%).

OH at measurement 1, however, was linked to the highest number of incidents and/or mortality rates of fracture, syncope, and death, whereas OH at measurement 2 was associated with the highest number of falls and motor vehicle crashes.

Early identification of OH is imperative in preventing adverse events through immediate treatment. “This suggests that the clinical practice of early OH assessments may be more informative than the consensus recommendation in terms of both characterizing concurrent symptoms and identifying long-term risk,” the researchers wrote.

“As dizziness reflects the causal pathway for variable consciousness, possible presyncope or syncope, falls, fractures, and perhaps motor vehicle crashes, clinical measurements modeling measurement 1, that is, performed immediately after standing, may ultimately be the most clinically informative time measurement.”

Study Limitations

The researchers stated limitations regarding the use of data derived from the International Classification of Diseases, Ninth Revision, codes of hospital records and Centers for Medicare & Medicaid Services claims regarding fracture, syncope, and motor vehicle crashes that were not adjudicated. They also reported variability as to the length of time required by participants to stand and when time assessments were recorded. 

Reference

Juraschek SP, Daya N, Rawlings AM, et al. Association of history of dizziness and long-term adverse outcomes with early vs later orthostatic hypotension assessment times in middle-aged adults [published online July 24, 2017]. JAMA Intern Med. doi:10.1001/jamainternmed.2017.2937