Home blood pressure self-monitoring. Influence of the mean calculation used on the diagnosis of white-coat hypertension

To describe the variations in the diagnosis performance of home blood pressure self-monitoring (hBPSM) with different methods for mean calculation, in order to diagnose white-coat hypertension (WCH). Multi-centre, descriptive, and comparative study to assess the diagnosis performance of a test method. Four primary health care centres. A total of 157 recently-diagnosed, untreated patients with mild-moderate hypertension took part in the study. The results obtained with hBPSM (3 consecutive days with readings in triplicate, morning-night) were compared with a "gold standard" out-patient blood pressure reading (OutBP). Systolic and diastolic BP values of the first day and first reading (morning-night) were higher than the remaining days and readings (linear trend P< .001). Results in hBPSM diagnostic performance using all readings to calculate the mean were: sensitivity (S), 47.6%; specificity (Sp), 77.4%; positive and negative predictive values (PPV and NPV), 58.8% and 68.6%, with positive and negative probability coefficients (PPC and NPC), 2.10 and 0.67. When readings with greater patient alarm reaction (first day and first reading, morning-night) were removed, greater values of S (61.9%) were obtained, albeit at expense of an excessive loss in Sp (64.5%) and without improvement in PPC (1.74). The diagnostic performance of hBPSM in WCH was low and failed to improve with the use of different systems to calculate mean BP.