Central versus lower body obesity distribution and the association with lower limb physical function and disability.
OBJECTIVE
To determine whether fat distribution in obese adults is significantly associated with decreased function and increased disability.


DESIGN
Cross-sectional epidemiologic analysis.


SETTING
Multicenter, community-based study.


PARTICIPANTS
Multicenter Osteoarthritis Study participants included adults ages 50-79 years at high risk of developing or already possessing knee osteoarthritis. A total of 549 men and 892 women from the Multicenter Osteoarthritis Study who had a body mass index ≥ 30 kg/m² and who underwent dual energy x-ray absorptiometry (DEXA) scans were included in these analyses. Exclusion criteria included bilateral knee replacements, cancer, or other rheumatologic disease.


METHODS
Body fat distribution was determined using baseline DEXA scan data. A ratio of abdominal fat in grams compared with lower limb fat in grams (trunk:lower limb fat ratio) was calculated. Participants were divided into quartiles of trunk:lower limb fat ratio, with highest and lowest quartiles representing central and lower body obesity, respectively. Backward elimination linear regression models stratified by gender were used to analyze statistical differences in function and disability between central and lower body obesity groups.


MAIN OUTCOME MEASURES
Lower limb physical function measures included 20-meter walk time, chair stand time, and peak knee flexion and extension strength. Disability was assessed using the Late Life Function and Disability Index.


RESULTS
Trunk:lower limb fat ratio was not significantly associated with physical function or disability in women or men (P value .167-.972). Total percent body fat (standardized β = -0.1533 and -0.1970 in men and women, respectively) was a better predictor of disability when compared with trunk:lower limb fat ratio (standardized β = 0.0309 and 0.0072).


CONCLUSIONS
Although fat distribution patterns may affect clinical outcomes in other areas, lower limb physical function and disability do not appear to be significantly influenced by the distribution of fat in obese older adults with, or at risk for, knee osteoarthritis. These data do not support differential treatment of functional limitations based on fat distribution.