Prognostic superiority of daytime ambulatory over conventional blood pressure in four populations: a meta-analysis of 7030 individuals

Abstract

To investigate the multivariate-adjusted predictive value of systolic and diastolic blood pressures on conventional (CBP) and daytime (10–20 h) ambulatory (ABP) measurement. We randomly recruited 7030 subjects (mean age 56.2 years; 44.8% women) from populations in Belgium, Denmark, Japan and Sweden. We constructed the International Database on Ambulatory blood pressure and Cardiovascular Outcomes. During follow-up (median = 9.5 years), 932 subjects died. Neither CBP nor ABP predicted total mortality, of which 60.9% was due to noncardiovascular causes. The incidence of fatal combined with nonfatal cardiovascular events amounted to 863 (228 deaths, 326 strokes and 309 cardiac events). In multivariate-adjusted continuous analyses, both CBP and ABP predicted cardiovascular, cerebrovascular, cardiac and coronary events. However, in fully-adjusted models, including both CBP and ABP, CBP lost its predictive value (P ≥ 0.052), whereas systolic and diastolic ABP retained their prognostic significance (P ≤ 0.007) with the exception of diastolic ABP as predictor of cardiac and coronary events (P ≥ 0.21). In adjusted categorical analyses, normotension was the referent group (CBP < 140/90 mmHg and ABP < 135/85 mmHg). Adjusted hazard ratios for all cardiovascular events were 1.22 [95% confidence interval (CI) = 0.96–1.53; P = 0.09] for white-coat hypertension (≥ 140/90 and < 135/85 mmHg); 1.62 (95% CI = 1.35–1.96; P < 0.0001) for masked hypertension (< 140/90 and ≥ 135/85 mmHg); and 1.80 (95% CI = 1.59–2.03; P < 0.0001) for sustained hypertension (≥ 140/90 and ≥ 135/85 mmHg). ABP is superior to CBP in predicting cardiovascular events, but not total and noncardiovascular mortality. Cardiovascular risk gradually increases from normotension over white-coat and masked hypertension to sustained hypertension.