Patient self-monitoring of blood pressure in general practice: the 'inverse white-coat' response.

Self-monitoring of blood pressure may give a truer estimate of usual blood pressure than readings by a doctor in the surgery, and may save time for health professionals. This study aimed to determine the accuracy of self-monitoring in the surgery using a wrist oscillometric sphygmomanometer (Omron RX). One hundred and seventy-three patients were taught to record their own blood pressure with the Omron RX. One hundred and nineteen patients recorded three self-measurements at monthly intervals, and their readings were compared with those of an experienced nurse using the Omron RX and a mercury sphygmomanometer. On average, patients' readings were higher than the nurse's readings (mean difference in phase 1 = systolic pressure 4.7 +/- 13.1 mmHg, diastolic pressure 2.7 +/- 9.3 mmHg [both P < 0.001]). Only half of the patients' readings were within 10 mmHg systolic and 5 mmHg diastolic of the nurse's readings. The readings by the nurse using both devices did not differ.