Mortality risks in different subtypes of white-coat hypertension: implications for the diagnosis of white-coat hypertension.

BACKGROUND: The risk associated with white-coat hypertension is controversial. We evaluated mortality risks in white-coat hypertension subtypes defined according to the circadian pattern of blood pressure (BP) elevation over 24 h. METHODS: In 44 119 patients with elevated office BP, white-coat hypertension subtypes were defined as normal BP in all circadian periods (day, night, and 24-h, 12 192 patients), normal 24-h, with nocturnal BP elevation (4368), and normal daytime, with 24-h BP elevation (3525). Associations of each subtype with all-cause and cardiovascular mortality were estimated by Cox-regression models, adjusted for clinical confounders, compared to a reference group of 7690 patients with normal both office and ambulatory (all periods) BP. RESULTS: Compared to the reference group, white-coat hypertension defined by normal BP in all circadian periods was not associated with an increased risk of all-cause [hazard ratio, 0.94 [95% confidence interval, 95% CI,0.85-1.03]) or cardiovascular death (hazard ratio, 0.91 [95% CI,0.76-1.08]). In contrast, white-coat hypertension defined by normal daytime, but with elevated 24-h BP, was associated with increased risks of all-cause (hazard ratio, 1.27 [95% CI,1.13-1.42]) and cardiovascular death (hazard ratio, 1.37 [95% CI,1.12-1.68]). The group of white-coat hypertension defined by normal 24-h BP, but with nocturnal BP elevation had increased crude rates of death, but risks were not significantly increased after adjusting for confounders. CONCLUSION: White-coat hypertension is a heterogeneous condition in terms of associated risk of death. A definition based only on a normal daytime BP may mask a significant group of patients with increased 24-h or night BP, who exhibit an increased risk of mortality.