Measuring blood pressure in the elderly: does atrial fibrillation increase observer variability?

Objective: To compare the interobserver and intraobserver variability of blood pressure measurements in geriatric patients in atrial fibrillation and in sinus rhythm.

Design: Prospective assessment of blood pressure measurements carried out in random order in two groups of elderly patients by five doctors unaware of the aims of the study.

Setting: Acute assessment wards for geriatric medicine, Cardiff Royal Infirmary.

Patients: 50 Elderly patients in sinus rhythm and 50 in atrial fibrillation.

Main Outcome Measures: Interobserver and intraobserver variability of blood pressure measurements in the two groups expressed as the coefficient of variability and compared by the Mann-Whitney U test.

Results: Interobserver variability was significantly greater in the patients with atrial fibrillation for both systolic and diastolic pressures. Intraobserver variability was significantly greater in the atrial fibrillation group for diastolic pressures but the difference was not significant for systolic pressures. These differences were not related to pulse rate, age, or level of blood pressure.

Conclusions: The findings suggest that in the presence of atrial fibrillation physicians' interpretations of Korotkoff sounds are less uniform, which may have important clinical implications. Possibly a standardised methodology may overcome this problem.