Validating prediction equations for mid-arm circumference measurements in adults: National Health and Nutrition Examination Survey, 2001-2012.

Abstract

Accurate measurement of blood pressure (BP) requires choosing an appropriate BP cuff size. The objective of this study was to examine the validity of regression equations to predict mid-arm circumference (mid-AC) using 2001-2012 National Health and Nutrition Examination Survey height and weight data. National Health and Nutrition Examination Survey uses a complex multistage probability sample design to represent the civilian, noninstitutionalized US resident population. The sample consisted of 29 745 participants aged 20 years and older. For both men and women, the correlations between the predicted and measured mid-AC values were as follows: r=0.91 and 0.92, P<0.001, respectively. For both sexes, the difference between the predicted and measured mid-AC mean values was less than 1.5 cm. The overall percent agreement for selecting the appropriate BP cuff, using the American Heart Association cuff size criteria and comparing the predicted mid-AC values with measured values, was 83.0% for men and 80.0% for women. The percent agreement for small adult cuff was 10.0% for men and 54.0% for women; for adult cuff it was 87.0% for men and 88.0% for women; for large adult cuff it was 82.0% for men and 80.0% for women; and for thigh cuff it was 84.0% for men and 74.0% for women. All agreement statistics were above chance (for men, γ=0.96, and Kendall's Tau-b=0.73; for women, γ=0.97, and Kendall's Tau-b=0.76). When possible, mid-AC should be directly measured for appropriate BP cuffing; however, the results of this validation study suggest that the prediction equations for mid-AC estimations were highly correlated and had an overall 80.0% agreement with measured mid-AC.