FRACTURE RISK IN OBESE OLDER ADULTS WITH PHYSICAL FRAILTY: A NEW PHENOTYPE OF BONE FRAILTY?

Abstract

An obese body weight, once presumed protective against bone fractures in older adults, has recently been linked with reduced bone quality. Thus, we assessed indicators of fracture risk in obese (mean BMI 35 ± 5 kg/m2) female (n=58) and male (n=16) older adults (age =70 ± 6 yrs; 49% black) with functional limitations (mean Short Physical Performance Battery score = 8.9 ± 1.5 out of 12) who had qualified for an obesity reduction trial. Measurement of bone mineral density (BMD) using DEXA (Hologic, Horizon model A) in hip (femoral neck and total) and spine (lumbar vertebrae 1–4) revealed 11% had osteoporosis (t-score ≥ -2.5) and 30% had osteopenia (t-score -1.1 to -2.4). Thus, >40% of the cohort had either osteoporosis or osteopenia, including 8% of men (all with osteopenia) and 25% of black participants (1 osteoporosis; 8 osteopenia). As an indicator of need for treatment, Fracture Risk Assessment Tool (FRAX) scores were calculated for those with osteopenia using femoral neck BMD, height, weight, age, gender, and race. None met the >20% major fracture threshold but 6 (all white) met the >3% hip fracture threshold. Thus, 17% (n=14) of the study population qualified for osteoporosis treatment as well as obesity reduction. These findings challenge the assumption that obesity protects against fracture. Fracture risk should be evaluated in obese older adults who are physically frail and this screening should include blacks as well as whites and men as well as women.