Self-reported height, calculated height, and derived body mass index in assessment of older adults

Body mass index (BMI) is frequently used as assessment of nutritional and health risk. Yet, there is no consensus regarding assessment of height and cutpoints for weight classification in older adults. We first investigated differences in height by self-report (SR-height) and height calculated from measured knee-height (KH-height) and derived BMI in a cross-sectional assessment of 145 older adults residing in a Midwestern United States city. We further compared the proportion of older adults classified as at risk by seven different BMI cutpoints for weight classification as reported in the literature. We found no substantive difference in SR-height and KH-height or derived BMI, but we did find significant differences in the proportions of participants classified as At Risk across different BMI cutpoints. In community and clinical practice, SR-height and KH-height, and BMI derived from these, can be used interchangeably, but the lack of consensus regarding BMI cutpoints could lead to misclassification of older adults at risk.