Impact of obesity on disability, function, and physical activity: data from the Osteoarthritis Initiative

Objectives: Older adults with obesity are at risk for osteoarthritis (OA) and are predisposed to functional decline and disability. We examined the association between obesity and disability, physical activity, and quality of life at 6 years.Method: Using data from the longitudinal Osteoarthritis Initiative (OAI), we analysed older adults (age 60 years) with a body mass index (BMI) at baseline 18.5 kg/m(2) (n = 2378) using standard BMI categories. Outcomes were assessed at the 6-year follow-up and included: the Late-Life Function and Disability Index (LLDI), the 12-item Short Form Health Survey (SF-12), and the Physical Activity Scale for the Elderly (PASE). Linear regression predicted outcomes based on BMI category, adjusting for age, sex, race, education, smoking, cohort status, radiographic knee OA, co-morbidity scores, and baseline scores when available.Results: Follow-up data were available for 1727 (71.9%) participants (mean age 67.9 5.3 years; 61.6% female). At baseline, obese subjects compared to overweight and normal were on a greater number of medications (4.28 vs. 3.63 vs. 3.32), had lower gait speeds (1.22 vs. 1.32 vs. 1.36 m/s), higher Charlson scores (0.59 vs. 0.37 vs. 0.30), and higher Western Ontario and McMaster University OA Index (WOMAC) scores (right: 14.8 vs. 10.3 vs. 7.5; left: 14.4 vs. 9.9 vs. 7.5). SF-12 scores at 6 years were lower in obese patients than in overweight or normal [99.5 (95% CI 98.7-100.4) vs. 101.1 (95% CI 100.4-101.8) vs. 102.8 (95% CI 101.8-103.8)], as were PASE scores [115.1 (95% CI 110.3-119.8) vs. 126.2 (95% CI 122.2-130.2) vs. 131.4 (95% CI 125.8-137.0)]. The LLDI limitation component demonstrated differences in obese compared to overweight or normal [78.6 (95% CI 77.4-79.9) vs. 81.2 (95% CI 80.2-82.3) vs. 82.5 (95% CI 81.1-84.0)].Conclusions: Obesity was associated with worse physical activity scores, lower quality of life, and higher risk of 6-year disability.