An evaluation of self-recorded blood pressure during drug trials.

To our knowledge, there have been no published comparisons of different techniques for measuring blood pressure during clinical trials. We undertook a comparison during clinical trials with verapamil and prazosin. During an open trial of verapamil we compared the treatment-induced blood pressure reductions as measured by clinic, intra-arterial, and self-recorded methods. The mean reduction in blood pressure was 38 +/- 13.6/20 +/- 10.1 mm Hg for clinic blood pressure, 24 +/- 17.9/16 +/- 7.3 mm Hg for self-recorded blood pressure, and 23 +/- 12.3/19 +/- 10.1 mm Hg for mean daytime intra-arterial blood pressure. During prazosin treatment the mean reduction in blood pressure was 28 +/- 21.5/18 +/- 8.5 mm Hg for clinic blood pressure, 21 +/- 20.5/6 +/- 13.7 mm Hg for self-recorded blood pressure, and 18 +/- 19.2/5 +/- 9.6 mm Hg for mean daytime intra-arterial blood pressure. There was little agreement between methods within individual patients and for group comparisons of intra-arterial or clinic methods. There was, however, good agreement between intra-arterial and self-recorded methods. This study suggests that self-recorded blood pressure recording is suitable for monitoring efficacy of antihypertensive agents in a group of patients, although caution must be exercised when interpreting the effects of therapy when measured by indirect methods in an individual patient.