Prognostic Significance of the Magnitude of the White-Coat Effect in Hypertension

BACKGROUND: White-coat effect (WCE) is defined as the difference between office and daytime ambulatory blood pressure (BP). We aimed to evaluate the association between the magnitude of the WCE and all-cause and cardiovascular mortality in patients with hypertension. METHODS: Forty-five thousand three hundred twenty-nine patients with office SBP at least 130 and a WCE more than 0 mmHg and 37 447 with office DBP at least 80 mmHg and a WCE more than 0 mmHg were studied. Follow-up was 9.7 years. For either systolic or diastolic WCE, hazard ratios were calculated for 1 standard deviation increase in Cox-regression models adjusted for clinical confounders and 24-h SBP. In addition, the highest and mid tertiles of the WCE distribution were compared to the lowest tertile (reference group). RESULTS: In adjusted models, WCE was associated with all-cause mortality [hazard ratio for 1 SD increase: 1.13; 95% confidence interval (95% CI): 1.07-1.19, for systolic and 1.25; 95% CI: 1.17-1.34 for diastolic]. In addition, compared to the lowest tertile of the WCE distribution, the highest tertile of both systolic and diastolic WCE was associated with increased rates of all-cause mortality (1.15; 95% CI: 1.07-1.23 and 1.24; 95% CI: 1.13-1.35), respectively, for systolic and diastolic WCE, after adjustments. Similar results were observed for cardiovascular mortality. CONCLUSION: An exaggerated WCE effect is associated with increased rates of all-cause and cardiovascular mortality. This association, along with the presence of other cardiovascular risk factors, suggests that an exaggerated WCE is not merely the result of an alert reaction, but also associated with a more advanced disease.