Preventing misdiagnosis of ambulatory hypertension: algorithm using office and home blood pressures.

OBJECTIVES An algorithm for making a differential diagnosis between sustained and white coat hypertension (WCH) has been proposed - patients with office hypertension undergo home blood pressure monitoring (HBPM) and those with normal HBP levels undergo ambulatory blood pressure monitoring (ABPM). We tested whether incorporating an upper office blood pressure (OBP) cut-off in the algorithm, higher than the traditional 140/90 mmHg, reduces the need for HBPM and ABPM. METHODS Two hundred twenty-nine normotensive and untreated mildly hypertensive participants (mean age 52.5 +/- 14.6 years, 54% female participants) underwent OBP measurements, HBPM, and 24-h ABPM. Using the algorithm, sensitivity, specificity, and positive and negative predictive values (PPV, NPV) for sustained hypertension and WCH were assessed. We then modified the algorithm utilizing a systolic and diastolic OBP cut-off at a specificity of 95% for ambulatory hypertension - those with office hypertension but OBP levels below the upper cut-off underwent HBPM and subsequent ABPM, if appropriate. RESULTS Using the original algorithm, sensitivity and PPV for sustained hypertension were 100% and 93.8%, respectively. Despite a specificity of 44.4%, NPV was 100%. These values correspond to specificity, NPV, sensitivity, and PPV for WCH, respectively. Using the modified algorithm, the diagnostic accuracy for sustained hypertension and WCH did not change. However, far fewer participants needed HBPM (29 vs. 84) and ABPM (8 vs. 15). CONCLUSION In this sample, the original and modified algorithms are excellent at diagnosing sustained hypertension and WCH. However, the latter requires far fewer participants to undergo HBPM and ABPM. These findings have important implications for the cost-effective diagnosis of sustained hypertension and WCH.