COMPARISON OF REPEATED MEASUREMENT OF AMBULATORY AND CLINIC BLOOD-PRESSURE READINGS IN ISOLATED SYSTOLIC HYPERTENSION

Repeated clinic blood pressure measurement was compared with noninvasi ve ambulatory blood pressure monitoring in 10 elderly subjects with pe rsistent isolated systolic hypertension and 11 normotensive controls. Mean clinic blood pressures +/- Standard Deviation (SD), at visit 1 we re 165/81 +/- 12/7 mmHg and 136/87 +/- 14/10 mmHg respectively. Subjec ts were assessed on three subsequent occasions at weekly intervals. No ne were receiving antihypertensive or vasoactive medication. Clinical systolic and diastolic blood pressures were consistently higher than t he corresponding mean daytime ambulatory blood pressures in both clini cal groups at each of the visits. The difference was greater between t he systolic pressures than between the diastolic pressures and these d ifferences in systolic pressures were greater in the isolated systolic hypertensives (26 +/- 5 mmHg) than in the normotensives (7 +/- 18 mmH g). Daytime ambulatory readings aggregated from all four visits were n ormally distributed for both blood pressure components in both clinica l groups. In the isolated systolic hypertension group the clinic systo lic and diastolic blood pressure measurements corresponded to the 93rd and 85th percentiles of the ambulatory pressures respectively whereas in the normotensives the equivalent percentiles were 69 and 78. These results suggest a pressor response may largely account for the elevat ed systolic blood pressure seen in elderly subjects with sustained iso lated systolic hypertension based on clinic readings.