Comparison of the white-coat effect in community pharmacy versus the physician's office: the Palmera study

The aim of this study was to measure the community pharmacy white-coat effect (CPWCE) in treated hypertensive patients and to compare its magnitude with the WCE in the physician's office (POWCE). This cross-sectional study attempted to cover the treated hypertensive population, of more than 18 years of age and users of a rural CP located in Palmera (Valencia, Spain). Blood pressure (BP) was measured at three different settings, according to clinical guidelines: CP (three visits), PO (three visits), and home (4 consecutive days). The WCE was defined as the difference between the average CPBP or the average PO BP and the average home BP: CPWCE and POWCE, respectively. Differences between BP measurements were assessed by paired t-tests. The study sample consisted of 70 patients. The CPWCE was not significant, both for systolic BP (SBP) and for diastolic BP (DBP): 1.4 mmHg [standard deviation (SD): 11.3; 95% confidence interval (CI): -1.3 to 4.1] and -1.1 mmHg (SD: 7.5; 95% CI: -2.9 to 0.7), respectively. The POWCE was positive and statistically greater than 0 for SBP [13.3 mmHg (SD: 11.5); 95% CI: 10.5-16.0] and for DBP [2.4 mmHg (SD: 9.3); 95% CI: 0.2-4.6]. Finally, the POWCE was greater than the CPWCE both for SBP and for DBP (P<0.001). In this sample of treated hypertensive patients, the CPWCE was not statistically significant and was statistically lower than the POWCE.