Diagnosing orthostatic hypotension with continuous and interval blood pressure measurement devices

Orthostatic hypotension (OH) is defined as a drop in systolic blood pressure (SBP) of >= 20 mm Hg and/or a drop in diastolic blood pressure (DBP) of >= 10 mm Hg within 3 min of standing. The international guidelines recommend ideally diagnosing OH with a continuous blood pressure (BP) measurement device, although in daily practice interval BP measurement devices are used more often. We aimed to investigate the difference in observed prevalence of OH between an interval and a continuous BP measurement device. A total of 104 patients with a mean age of 69 years were included. The prevalence of OH was 35.6% (95% CI: 26.4-44.8) with the interval BP measurement and 45.2% (95% CI: 35.6-54.8) with the continuous BP measurement device (P = .121). Lin's coefficient of concordance ranged from 0.47 to 0.59 for the drop in systolic blood pressure and from 0.33 to 0.42 for the drop in diastolic blood pressure. The positive proportion of agreement in diagnosis of OH between the interval and continuous measure was 59.5% and the negative proportion of agreement was 72.5%. Although the prevalence of OH was not significantly different between the continuous and the interval BP measurement devices using a similar amount of measurement, the concordance between interval and continuous measure is low resulting in low positive and negative proportions of agreement in the diagnosis of OH. We conclude that continuous BP measurement cannot be substituted by an interval BP measurement to diagnose OH.