Mean and range of the ambulatory pressure in normotensive subjects.

To perform a meta-analysis of published reports in an attempt to determine the mean and range of normal ambulatory blood pressure (BP), 23 studies including a total of 3,476 normal subjects were reviewed. Most studies were compatible with a mean 24-h BP in the range of 115-120/70-75 mmHg, a mean day time BP of 120-125/75-80 mmHg, and a mean night time BP of 105 to 110/60 to 65 mmHg. With weighting for the number of subjects included in the individual studies, the 24-h BP averaged 118/72 mmHg, the day time BP 123/76 mmHg, and the night time BP 106/64 mmHg. The night/day pressure ratio averaged 0.87 for systolic and 0.83 for diastolic BP, with ranges across the individual studies from 0.79 to 0.92 and from 0.75 to 0.90, respectively. If the mean +/- 2 standard deviation interval in the various studies was considered normal, the range of normality was on average 97 to 139/57 to 87 mmHg for the 24-h BP, 101 to 146/61 to 91 mmHg for the day time BP, and 86 to 127/48 to 79 mmHg for the night time BP. Until the results of prospective studies on the relation between the ambulatory BP and the incidence of cardiovascular morbidity and mortality become available, the aforementioned intervals, which summarize the experience of 23 investigators, could serve as a temporary reference for clinical practice.