BONE MINERAL CONTENT AND BODY COMPOSITION IN ELDERLY REHABILITATION PATIENTS

Abstract

PURPOSE: The purpose of the study was to examine the relation between bone mineral content (BMC) and body composition variables in elderly long-term rehabilitation patients. METHODS: Total body fat mass (TBFM) and total body muscle mass (TBMM) was measured with Dual-Energy X-Ray Absorptiometry (DEXA) in 87 rehabilitation inpatients (age = 74.2, SD = 8.3; height = 69.2, SD = 2.9in.; weight = 170.6, SD = 41.1lb.) from the Houston VAMC. Right arm circumference and seven skinfolds were measured in all 87 patients. Zero order and partial correlations were used to examine the relation between BMC and body composition variables. A hierarchical multiple regression was used to determine if TBFM adds additional variance in BMC prediction above TBMM. RESULTS: A significant positive correlation was found between BMC and TBFM (r = 0.74; p < 0.001) and between BMC and TBMM (r = 0.618; p < 0.001) even after controlling for age and BMI. Age did not correlate with BMC or any other body composition variables. In addition, weight and BMI, alone, did not correlate with BMC. The seven skinfolds and arm circumference did not correlate with BMC either. Multiple regression analysis showed that 61% of the variance of BMC is aligned with TBMM and TBFM. Both TBMM and TBFM had a significant predictive validity (p < 0.001). CONCLUSIONS: TBMM and TBFM account for 61% of BMC variance in this population. TBFM had predictive validity and added significantly unique variance above and beyond TBMM. These findings can be attributed to the role of weight bearing in BMC in addition to the known effects of muscle mass. Supported by: NIH MO1 RR02719; National VA merit #2117; and the Houston VA National Center for Healthy Aging with Disabilities