Significance of white-coat hypertension in older persons with isolated systolic hypertension: a meta-analysis using the International Database on Ambulatory Blood Pressure Monitoring in Relation to Cardiovascular Outcomes population

Abstract

The significance of white-coat hypertension in older persons with isolated systolic hypertension remains poorly understood. We analyzed subjects from the population-based 11-country International Database on Ambulatory Blood Pressure Monitoring in Relation to Cardiovascular Outcomes database who had daytime ambulatory blood pressure (BP; ABP) and conventional BP (CBP) measurements. After excluding persons with diastolic hypertension by CBP (≥90 mm Hg) or by daytime ABP (≥85 mm Hg), a history of cardiovascular disease, and persons <18 years of age, the present analysis totaled 7295 persons, of whom 1593 had isolated systolic hypertension. During a median follow-up of 10.6 years, there was a total of 655 fatal and nonfatal cardiovascular events. The analyses were stratified by treatment status. In untreated subjects, those with white-coat hypertension (CBP ≥140/<90 mm Hg and ABP <135/<85 mm Hg) and subjects with normal BP (CBP <140/<90 mm Hg and ABP <135/<85 mm Hg) were at similar risk (adjusted hazard rate: 1.17 [95% CI: 0.87-1.57]; P=0.29). Furthermore, in treated subjects with isolated systolic hypertension, the cardiovascular risk was similar in elevated conventional and normal daytime systolic BP as compared with those with normal conventional and normal daytime BPs (adjusted hazard rate: 1.10 [95% CI: 0.79-1.53]; P=0.57). However, both treated isolated systolic hypertension subjects with white-coat hypertension (adjusted hazard rate: 2.00; [95% CI: 1.43-2.79]; P<0.0001) and treated subjects with normal BP (adjusted hazard rate: 1.98 [95% CI: 1.49-2.62]; P<0.0001) were at higher risk as compared with untreated normotensive subjects. In conclusion, subjects with sustained hypertension who have their ABP normalized on antihypertensive therapy but with residual white-coat effect by CBP measurement have an entity that we have termed, "treated normalized hypertension." Therefore, one should be cautious in applying the term "white-coat hypertension" to persons receiving antihypertensive treatment.

Figure 1

Incidence of cardiovascular events in untreated normotension (untreated NT), untreated isolated systolic hypertension (ISH) subjects with white-coat hypertension (untreated WCH), treated normotension (treated NT), and treated ISH subjects with white-coat hypertension (treated WCH). In untreated subjects with ISH, the risk in white-coat hypertensives was similar to that in normotensives (P=0.38). Similarly, in treated subjects with ISH, white-coat hypertension did not carry an increased risk (P=0.92) as compared with treated normotension. However, both treated ISH subjects with white-coat hypertension and treated subjects with normal blood pressure (treated NT) were at higher (P<0.007) cardiovascular risk as compared with the untreated normotensive reference group.

Figure 2

Incidence of cardiovascular events according to the cross-classification of subjects by conventional and daytime ambulatory blood pressure in normotensives and in persons with solated systolic hypertension (ISH) presenting with white-coat hypertension, masked hypertension, and sustained hypertension. The analyses included all of the cardiovascular events according to the broad definition. Incidence was standardized to the sex distribution (45% men) and mean age (48.8 years) in the whole study population. In the analysis including untreated subjects only (left), the incidence of cardiovascular events was significantly higher in sustained (P=0.0005) and masked hypertension (P<0.0001) as compared with normotension, whereas the risk in white-coat hypertension was similar to that in normotension (P=0.38). Similarly, in treated subjects with ISH (right), the incidence of cardiovascular events was significantly higher in sustained (P<0.0001) and masked hypertension (P=0.0013) as compared with treated normotension, whereas the risk in treated white-coat hypertension was similar to that in treated normotension (P=0.92). In both treated and untreated patients with ISH, the risk was similar in sustained and masked hypertension (P>0.33).