Calibrating Local Population-Based Blood Pressure Data from NYC HANES 2013-2014

New York City Health and Nutrition Examination Survey (NYC HANES) was a population-based cross-sectional survey of NYC adults conducted twice, in 2004 and again in 2013-2014, to monitor the health of NYC adults 20 years or older. While blood pressure was measured in both surveys, an auscultatory mercury sphygmomanometer was used to measure blood pressure in clinics in 2004, and an oscillometric LifeSource UA-789AC monitor was used in homes in 2013-2014. To assess comparability of blood pressure results across both surveys, we undertook a randomized study comparing blood pressure (BP) readings by the two devices. Blood pressure measuring protocols followed the 2013 Association for the Advancement in Medical instrumentation guidelines for non-invasive blood pressure device. Data from 167 volunteers were analyzed for this purpose.Paired t tests were used to test for significant difference in mean systolic and diastolic blood pressure between devices for overall and by mid-arm circumference categories. To test for systematic differences between the two devices, we generated Bland-Altman graphs. Sensitivity, specificity, and Kappa statistics were calculated to assess between-device agreement for high (≥ 130/80 mmHg) and not high (< 130/80 mmHg) blood pressure, with mercury set as the reference.Systolic and diastolic blood pressure measured by LifeSource UA-789AC were on average 2.0 and 1.1 mmHg higher, respectively, than those of the mercury sphygmomanometer systolic and diastolic blood pressure readings (P < 0.05). Sensitivity was 81%, specificity was 96%, and the Kappa coefficient was 75%. The Bland-Altman graphs showed that the between-device difference did not vary as a function of the average of the two devices for systolic blood pressure and was larger in the lower and upper ends for diastolic blood pressure. Given the observed differences in systolic and diastolic blood pressure readings between the two blood pressure measurement approaches, we calibrated NYC HANES 2013-2014 blood pressure data by predicting mercury blood pressure values from LifeSource blood pressure values. The mean systolic and diastolic blood pressure in NYC HANES 2013-2014 were lower when data were calibrated.