Deep breathing: A simple test for white coat effect detection in primary care

Aim. White coat hypertension (WCH) is hard to differentiate from sustained hypertension without the use of 24-h ambulatory blood pressure monitoring (ABPM). This invaluable procedure is nevertheless cumbersome and expensive. A simple test of deep breathing over 30 s (DBT) was proposed as a method to unveil WCH. Methods. Two hundred and fourteen outpatients referred for the evaluation of uncontrolled hypertension (blood pressure, BP > 140/90 mmHg despite therapy) were enrolled in a controlled clinical trial. The examinees were randomly divided in two groups: control (n = 108; sequential standard BP measurement only) and intervention (n = 106; the same+DBT), using ABPM as the reference standard. Results. The relative decrease in BP was significantly larger in the intervention group than in the control group, by 15/4 mmHg (p = 0.005). The best detection of WCH was obtained at >= 15% systolic BP reduction following DBT, with a positive predictive value of 94.0% (95% CI 72.0-100.0). BP reduction of <= 8% may rule WCH out with a negative predictive value of 78.4% (95% CI 64.0 - 85.9). Conclusion. DBT is a reliable, inexpensive and fast test for the detection of WCH in primary care.