An analysis of the HYVET data suggests that white-coat hypertension (WCH) may account for a large number of strokes in the very elderly, and should be treated.
Half of 284 HYVET (Hypertension in the Very Elderly Trial) participants who underwent ambulatory blood pressure (ABP) monitoring had WCH; their average clinic blood pressure exceeded morning ABP readings by 32/10 mmHg.
The main trial results, in 3485 patients aged at least 80 years, showed that active versus placebo antihypertensive treatment resulted in a 30% reduction in stroke, a 21% reduction in total mortality, and a 34% reduction in any cardiovascular event over an average 13-month follow up.
"If WCH does not require treatment it would be surprising that the benefits of treatment were so great," comment Chakravarthi Rajkumar (Brighton and Sussex Medical School, UK) and colleagues in Hypertension.
During follow up, average morning ABP fell by 6/5 mmHg with active versus placebo treatment, 24-hour ABP fell by 8/5 mmHg, and clinic blood pressure fell by 13/5 mmHg.
ABP is often considered more predictive of renal and cardiovascular events than is clinic blood pressure, but most of the HYVET participants did not have hypertension according to ABP. The average readings at baseline were 140/80 mmHg in the morning, when blood pressure was highest, and 133/77 mmHg over 24 hours.
By contrast, average sitting baseline clinic blood pressure was 172/90 mmHg. Rajkumar et al observe that ABP is known to fall, relative to clinic blood pressure, as people age, "leading to our finding that the very elderly have hypertension as determined by [clinic blood pressure] but not necessarily when assessed by ambulatory blood pressure monitoring."
Thus, as people age, the two "arbitrary" definitions of hypertension diverge, they say, "and it is unlikely that the present definition of WCH is appropriate over 80 years of age."
The researchers conclude: "We suggest that WCH may need active treatment in the very elderly or the definition of WCH needs to be changed for this age group."
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