Prognostic Impact of Different Definitions of White-Coat Hypertension.

Background: Different definitions of white-coat hypertension (WCH) may explain its variable outcome across studies.

Methods: In an Italian study started in year 1986, we followed 3,153 people with (office blood pressure (BP) >=140/90 mmHg) and 457 without office hypertension for a mean of 10.4 years. None had previous cardiovascular disease. All underwent 24-hour ambulatory BP (ABP) monitoring. We defined WCH as an average 24-hour ABP <130/80 mmHg or <125/75 mmHg. Primary outcome was a composite of major adverse cardiovascular events (MACE), and all-cause mortality.

Results: Baseline office BP was 156/97 mmHg in people with and 127/81 mmHg without hypertension. At follow-up, MACE events were 344 and 23, and all-cause deaths 318 and 24 in people with and without hypertension, respectively. Compared to normotensive group, MACE risk was not higher in people with WCH and 24-hour ABP <125/75 mmHg (hazard ratio (HR), 0.94; 95% confidence interval (CI), 0.42-2.10). Compared to normotensive group, MACE risk was higher in people with WCH and 24-hour ABP <130/80 mmHg (HR: 1.79; 95% CI: 1.07-2.29). All-cause death did not differ between the normotensive group and people with WCH and 24-hour ABP <125/75 mmHg (HR 1.37; 95% CI 0.68-2.73), but it was higher than in the normotensive group when WCH was defined by a 24-hour ABP <130/80 mmHg (HR 1.82; 95% CI 1.55-3.58).

Conclusions: WCH defined by an average 24-hour ABP <125/75 mmHg identifies people at low risk of MACE and death in the long-term. Even modestly above these threshold values, the risk associated with WCH increases.