White-coat effect on orthostatic hypotension: a nationwide survey of Japanese general practitioners

Objective The relationship between the white-coat effect (WCE), defined as white-coat hypertension under treatment, and the frequency of orthostatic hypotension (OH) is not known. We conducted an orthostatic test in patients with WCE to determine the frequency of OH. Methods This was a cross-sectional study of 5631 patients with hypertension visiting general practitioners nationwide, in which 4305 patients with hypertension recorded their home blood pressure (BP) and consented to the orthostatic test. Patients with hypertension were divided into four groups: controlled hypertension (CHT), masked hypertension (MHT), sustained hypertension (SHT), and WCE. The orthostatic test was performed, and BP and pulse rate were measured immediately and 1 min after orthostasis. Results The OH frequencies immediately after standing in CHT, WCE, SHT, and MHT patients were 7, 11.7, 12.1, and 6.6%, respectively, and those at 1 min after standing were 7.1, 13.1, 11.6 and 6.9%, respectively (Chi-square test, P < 0.01, respectively). Logistic regression analysis was performed to examine the relationship between WCE and the frequency of OH. The frequency of OH immediately after standing was significantly increased [adjusted odds ratio (AOR), 1.702; 95% confidence interval (CI), 1.246-2.326; P < 0.01]. The frequency of OH at 1 min after standing was also significantly higher (AOR, 1.897; 95% CI, 1.396-2.578; P < 0.01). Conclusion When the standing test was performed for patients with WCE, the frequency of OH increased. Thus, it is important to recognize the possibility of OH in patients with WCE to avoid adverse events associated with excessive hypotension.