VARIATION OF WITHIN VISIT BLOOD-PRESSURE READINGS AT A SINGLE VISIT IN THE ELDERLY AND THEIR RELATIONSHIP TO AMBULATORY MEASUREMENTS

The value of routinely taking one or several BP readings at a single v isit in subjects with an initially elevated BP reading is unclear. The variation of sequential BP readings in the elderly, who often have a disproportionate increase in SBP compared with DBP, has received littl e attention. In addition, no attempt has been made to relate the vario us BP readings obtained to a subject's ambulatory daytime BP. The aim of this study was to examine the variation in BP between one, two or t hree readings at a single visit in elderly subjects with elevated BPs and to compare these readings with those obtained from daytime ambulat ory BP monitoring (ABPM). Sixty-nine subjects, mean age 76 years (rang e 66-86 years) with at least one SBP reading > 150 mmHg and who had un dergone a minimum of two previous clinic visits for BP measurement by the same physician were included. Following five minutes rest three su pine BP readings were taken, spaced two minutes apart, using a Hawksle y random zero sphygmomanometer. Seventeen subjects underwent home 24h ABPM commencing immediately after the clinic BP readings. Clinic SBP f ell from first to third reading by 11 mmHg (95% Cl 9-13mmHg, P<0.001) and from first to second readings by 6 mmHg (Cl 4-8 mmHg, P < 0.01). T here was no change in mean DBP between readings. In 85% of readings fi rst SBPs were higher than the second. There were 55% of subjects who h ad a > 10 mmHg SBP fall between first and third readings; this decreas e was unrelated to mean SBP levels. Daytime ambulatory SBP was lower t han the lowest mean clinic readings (1 7 mmHg, 95% Cl 8-26 mmHg, P < 0 .002) although ambulatory and clinic DBP were similar. Clinic SBP but not DBP tends to fall on repeated recordings in elderly subjects. The lowest clinic SBP is closest to, but remains significantly higher than , daytime ambulatory SBP. It is suggested that the lowest or mean of t he two lowest SBP readings are used to define a subject's BP at each v isit. This should result in a lower assessment of a subject's SBP and in particular, a reduction in the number of elderly subjects being fal sely diagnosed as having isolated systolic hypertension.