Background: Orthostatic hypotension (OH) is a major problem in the elderly population. Its diagnosis is based on measurement of the blood pressure (BP) response to orthostatism (BPRO). This study investigates the within-day and day-to-day variability of the BPRO and the reproducibility of the diagnosis of OH in this population.
Methods: BP was measured in the supine position and after 1 and 2 minutes of orthostatism in 53 consecutive elderly patients (43 women and 10 men aged 83.7 +/- 9.5 years) of an intermediate care geriatric ward. BPRO was assessed 4 times on the same day (8-9 AM, 10-11 AM, 1-2 PM, and 5-6 PM) and twice more on another day of the same week (8-9 AM and 1-2 PM).
Results: There were significant within-day differences between the four orthostatic changes in systolic BP (OCs, supine minus standing systolic BP) after 1 minute or 2 minutes (p < .05). Day-to-day differences between the OCs measured at the same times were not significant. OH defined as an OCs of 20 mm Hg or more at 1 or 2 minutes of orthostatism, was found in ten cases (19%) in the initial set of measurements on the first day. A cumulative diagnosis of OH after the six BPRO tests was found in 23 cases (43%). The reproducibility of the diagnosis of OH was mild or poor (all kappa values were below 0.47).
Conclusions: BPRO exhibits significant within-day variability in elderly patients. Within-day and day-to-day reproducibility of the diagnosis of OH, based on conventional criteria, were found to be poor.