Identifying Osteosarcopenic Obesity in a Group of Older Women

A cross-sectional study in older women was designed and conducted to identify prevalence, specific characteristics and diagnostic criteria for the newly identified condition named osteosarcopenic obesity syndrome. Osteosarcopenic obesity (OSO) is a condition where an older adult experiences bone loss, sarcopenia and increased fat mass, the latter either as a clinically diagnosed overweight/obesity, or infiltrated fat into bone and muscle. The study lasted 24 months and a total of N=59 Caucasian ambulatory women aged 76.0±7.3 years (mean ± SD) and BMI of 27.0±5.5 kg/m2 from the local area were assessed for body composition measurements (bone, muscle, fat tissue) using dual energy x-ray absorptiometry scans (DXA). Osteoporosis/osteopenia was identified based on femoral neck and lumbar spine (L1-L4) T-scores (≤-1). A linear regression model was created to identify sarcopenic obesity in the sample, based on the appendicular lean mass, controlling for height (m) and fat mass (kg). Obesity status was based on percent body fat with a cut-off at ≥32%. Muscle quality was measured via echo intensity obtained via ultrasound scans as well as knee extension scores divided by lower appendicular lean mass. Bioelectrical impedance analyses were used to calculate phase angle to assess for frailty in the population. The participants were also tested on physical performance measures including handgrip strength, one-leg stance, 4-m timed normal and brisk walking test, 2-minute walking test, sit-to-stand, knee extension and arm flexion. In the final analysis, the women were divided into four groups based on body composition: OSO (n=10), osteopenic obese (OO; n=35), obese-only (obese; n=10) and osteopenic/sarcopenic non-obese (non-obese; n=4). There was also one participant who had sarcopenic obesity (SO), however due to the small sample size (n=1), was not included in the calculations. All data analyses were performed in SAS 9.4.with p<0.05 deemed as statistically significant. As expected, the OSO women presented with lower bone mineral density (BMD) at most skeletal sites in comparison to other groups (although not always significantly different): right femoral neck BMD (OSO: 0.778±0.080; OO: 0.792±0.082; obese: 1.013±0.102; non-obese: 0.773±0.048 g/cm2, p<0.05), left femoral neck BMD (OSO: 0.759±0.066; OO: 0.801±0.074; obese: 0.957±0.048; non-obese: 0.747±0.018 g/cm2, p<0.05) and lumbar spine BMD (OSO: 1.133±0.139; OO: 1.182±0.184; obese: 1.394±0.212; non-obese: 1.064±0.136 g/cm2, p<0.05). The OSO women had significantly lower appendicular lean mass (OSO: 15.9±1.7; OO: 17±2.4; obese: 18.5±2.7; non-obese: 14±1.3 kg, p<0.05) and higher percent body fat (OSO: 45±4.9; OO 42.2±5.7; obese: 43.7±3.8; non-obese: 27.1±3.8%, p<0.05), on average than women in other groups. The OSO and OO women had the poorest scores on physical performance tests, with the OSO women scoring significantly lower on sit-to-stand (OSO: 10.3±1.6; OO: 11.9±4; obese: 10.9±3.3; non-obese: 14.3±2.6 times/30 sec, p<0.05) and the knee extension (OSO: 43±11; OO: 56±14.1; obese: 65.5±15.2; non-obese: 41.5±19.1 kg, p<0.05) than other groups. The OSO women also had lower muscle quality based on echo intensity (right quadriceps) from ultrasound measurements (OSO: 65.7±9.9; OO: 65.5±12; obese: 71±13.9; non-obese: 76.6±6.7 pixel intensity) and from the knee extension (OSO: 3.8±0.8; OO: 4.4±1.0; obese: 4.9±0.7; non-obese: 3.8±1.8 kg) calculation than other groups. Results from this study can be used to better recognize OSO syndrome in older women using body composition measures via DXA, physical performance tests and muscle quality measurements. These results also indicate that in situations when DXA is not available for body composition measurements for the OSO diagnosis, simple physical performance measures could be used for preliminary assessment and patient referrals for further evaluations.