Comparability of two commonly used automated office blood pressure devices in the severely obese

The accuracy of automated office blood pressure (BP) devices in severely obese individuals is unknown. In an exploratory study, we compared standardized BP measurements using a BpTRU device with those taken using a WatchBP Office monitor. Paired t-tests, Bland-Altman plots, and Pearson's correlations were used to compare devices. A total of 62 patients were analyzed: their mean age was 39.5±9.3 years and their mean BMI was 45.1±5.7 kg/m. Fifty-five patients (89%) were women and 21 (34%) had a diagnosis of hypertension. The mean BpTRU values were 117.2±12.7/76.7±9.7 mmHg and the mean WatchBP measurements were 126.6±13.8/79.7±10.9 mmHg [difference of -9.4±11.6 for systolic (P<0.0001) and -3.0±7.7 mmHg for diastolic (P=0.003)]. A Bland-Altman plot for systolic BP showed considerable variability. Only four (6.5%) patients had hypertension (>140/90 mmHg) according to BpTRU versus 15 (24%) according to WatchBP. In conclusion, the mean BP measurements taken using two commonly used automated office devices differed markedly and by a clinically important magnitude. These data indicate the need for formal validation of these devices specifically in severely obese individuals.