A consistent reference frame for ambulatory blood pressure monitoring is found in different populations.

This study investigated the consistency of a reference frame for ambulatory pressure monitoring, which using various approaches was determined in two different populations. The two reference groups were 718 subjects randomly selected from the population and 895 bank employees. The reference values derived in these two groups were subsequently tested in 591 untreated hypertensive patients. The ambulatory pressures equivalent to a conventional pressure of 140 mmHg systolic and 90 mmHg diastolic were calculated by regression analysis in all subjects. In addition, in subjects who were normotensive by conventional sphygmomanometry, the mean +2 and +3 standard deviations and the 90th, 95th and 99th percentiles of the ambulatory measurements were determined. The distributions of the ambulatory measurements were similar in the two reference groups and the aforementioned parameters therefore agreed within 4 mmHg in the two populations. There was considerable overlap in the ambulatory pressures between the two reference groups and the hypertensive patients. Classification of the patients according to the means +3 standard deviations and the regression limits gave the same results because in both reference groups these boundaries approximated to each other within 1 mmHg. For the 24 h pressures in the population sample these boundaries were 140 mmHg systolic and 88 mmHg diastolic. Of the patients with systolic hypertension (> or = 160 mmHg on conventional measurement), 39% had a 24 h systolic pressure of < 140 mmHg and of those with diastolic hypertension (> or = 95 mmHg), 44% had a 24 h diastolic pressure of < 88 mmHg; if the corresponding boundaries derived in the bank employees (143/90 mmHg) were applied, these proportions were 47% and 44%, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)