Prevalence and predictors of white-coat response in patients with treated hypertension

Background: White-coat response, defined as higher office blood pressure re adings than ambulatory readings, is common. Few studies have estimated its prevalence among subjects with treated hypertension, and almost none have d efined its determinants. The objective of this study was to estimate the pr evalence of white-coat response among subjects with treated hypertension an d to determine whether the phenomenon could be predicted using clinical and psychometric data. Methods: A total of 103 treated patients (55 men and 48 women) with uncontr olled hypertension who attended a hypertension outpatient clinic in Saskato on between September 1993 and December 1995 were entered into the study. Pa tients had at least 2 clinic blood pressure readings of 140/90 mm Hg or hig her, had no target organ damage or left ventricular hypertrophy, and had be en prescribed 2 or more classes of antihypertensive drugs. Patients had blo od pressure measured in the supine position in the clinic, were placed on 2 4-hour ambulatory blood pressure monitoring and then completed questionnair es before returning to the clinic. Patients were classified as exhibiting a white-coat response if their mean daytime ambulatory systolic/diastolic bl ood pressure was 139/89 mm Hg (both) or less, or ii the systolic/diastolic pressure was at least 20/15 mm Hg (both) lower than the clinic reading. Results: Eleven men (20%, 95% confidence interval [CI] 10%-33%) and 26 wome n (54%, 95% CI 39%-69%) showed white-coat response. Logistic regression mod elling showed that determinants such as stress had significantly different effects among men and women. Separate models were therefore created for men and women. For women, perceived level of stress was the most important pre dictor of white-coat response (odds ratio [OR] per unit 7.0, 95% CI 1.3-36. 0), followed by time since diagnosis. For men, depression was a weak predic tor, with higher depression scores predicting sustained hypertension (OR pe r unit 1.2, 95% CI 1.01-1.5). Interpretation: Sex is an important factor in white-coat response. Attempts to predict white-coat response from psychometric variables should take sex differences into account. Clinical variables were not effective as predict ors of white-coat response.