Comparing the Effects of White Coat Hypertension and Sustained Hypertension on Mortality in a UK Primary Care Setting

PURPOSE We examined all-cause mortality within a primary care setting in patients with white coat hypertension or sustained hypertension in whom blood pressure (BP) monitoring was indicated. METHODS This prospective multicenter study of ambulatory BP monitoring included 48 family practices in the county of Oxfordshire, United Kingdom. Mortality was compared for patients having white coat hypertension (mean of 3 clinic BP readings >140/90 mm Hg and daytime ambulatory readings >135/85 mm Hg) and patients having sustained hypertension (mean of 3 clinic readings >140/90 mm Hg and daytime ambulatory readings >135/85 mm Hg). RESULTS A routine primary care cohort consisting of 5,182 patients chosen to undergo ambulatory BP monitoring by their family physician was followed up for a median of 7.3 years (interquartile range, 5.8-8.9). There were 335 deaths (6.5%), corresponding to a mortality rate of 8.9 deaths (95% confidence interval [Cl], 8.0-9.9) per 1,000 years of follow-up. Patients with white coat hypertension (n = 1,117) were more likely to be female and were on average younger than patients with sustained hypertension (n = 4,065). The unadjusted rate of all-cause mortality in patients with white coat hypertension was lower, at 4.4 deaths per 1,000 years of follow-up (95% CI, 3.1-6.0) than that in patients with sustained hypertension, at 10.2 deaths per 1,000 years of follow-up (95% CI, 9.1-11.4). This reduction in all-cause mortality was still clinically significant after adjustment for age, sex, smoking, use of anti hypertensive medication, and practice-clustering effects (hazard ratio = 0.64; 95% CI, 0.42-0.97; P = .04). CONCLUSIONS White coat hypertension (elevation of clinic BP only) confers significantly less risk of death than sustained hypertension (elevation of both clinic and ambulatory BPS). Trials are now needed to evaluate the risk reduction achievable in patients who have white coat hypertension and are receiving BP-lowering therapy. Ann Fam Med 2008:5;390-396. DOI: 10.1370/afm.865.