White coat effect can be an illusion that may possibly result in sub-optimal blood pressure control?

摘要

Objectives: To study how accurate is the discrepancy between the home blood pressure and clinic blood pressure readings being attributed to white coat effect in hypertensive patients. Design: Cross-sectional study. Subjects: From Februar y 2015 to July 2015, we recruited hypertensive patients, who had recent three clinic visits showing elevated clinic blood pressure (BP), from the general outpatient clinics within one Hospital Authority cluster for our study. They should have had normal Home Blood Pressure Monitoring (HBPM) results and did not receive any hypertensive medication adjustment. Main outcomes: 1) The proportion of sub-optimal blood pressure control (SOBP) patients in suspected ‘White Coat Effect’ (WCE) patients. 2) The associated factors of the SOBP groups among suspected WCE patients. Methods and Resul ts: Among 112 pat ient s we recruited for the study, 106 patients completed the study. They also had undergone 24-hour ambulatory blood pressure monitoring (ABPM) and each completed a self-administered questionnaire. After analysing the 24-hour ABPM study results, the percentage of true WCE in our study was only 58.5% and SOBP group was as high as 41.5%. Higher proportion of subjects (53.2%; p = 0.01) with true WCE was found in the groups of patients who had learnt HBPM technique from health professionals as compared to those (46.8%) who had not. There were longer histories of HBPM in the SOBP group (6.9±4.9 years) compared to those in the true WCE group (5.1±4.1 years; p=0.04). The clinic systolic blood pressure (SBP) of the subjects was slightly higher in the SOBP group (158±13 mmHg) than in the true WCE group (154±9 mmHg; p=0.04). Conclusion: In this study, substantial amount (> 40%) of patients labelled as having WCE were actually having suboptimal BP control. Therefore, 24-hour ABPM should be offered to patients who were suspected to have WCE in order to guarantee a better blood pressure control for these patients. We suggest that all patients with hypertension should attend the HBPM technique classes to have an accurate measurement of their BP. The longer the history of the home blood pressure measurement or the higher the SBP, the more likely the patients had suboptimal BP control than having WCE. Patients with HBPM should be assessed by nurses on their BP measurement technique that may reduce the proportion of suboptimal BP control in patients with suspected WCE.