A Comparison of Casual In-Clinic Blood Pressure Measurements to Standardized Guideline-Concordant Measurements in Severely Obese Individuals

Background/Objectives. The objective of this study was to compare casual BP taken in a bariatric clinic to standardized guideline-concordant BP. Subjects/Methods. A cross sectional analysis was performed using baseline data from a weight management trial. Patients were recruited from a Canadian bariatric care program. Standardized BP was performed using a Watch BP oscillometric device. Casual in-clinic BP single readings, taken using a Welch Allyn oscillometric device, were chart-abstracted. Paired t-tests, Bland-Altman plots, and Pearson's correlations were used for analysis. Results. Data from 134 patients were analyzed. Mean age was 41.5 ± 8.9 y, mean BMI was 46.8 ± 6.5 kg/m(2), and 40 (30%) had prior hypertension. Mean casual in-clinic BP was 128.8 ± 14.1/81.6 ± 9.9 mmHg and mean standardized BP was 133.2 ± 15.0/82.0 ± 10.3 mmHg (difference of -4.3 ± 12.0 for systolic (p < 0.0001) and -0.4 ± 10.0 mmHg for diastolic BP (p = 0.6)). Pearson's coefficients were 0.66 (p < 0.0001) for SBP and 0.50 (p < 0.0001) for DBP. 28.4% of casual versus 26.9% of standardized measurements were ≥140/90 mmHg (p < 0.0001). Conclusion. In this bariatric clinic, casual BP was unexpectedly lower than standardized BP. This could potentially lead to the underdiagnosis of hypertension.