Do knee osteoarthritis and fat-free mass interact in their impact on health-related quality of life in men? Results from a population-based cohort.

Objective: To investigate whether obesity and other risk factors interact with knee osteoarthritis (OA) in its adverse impact on health-related quality of life (HRQOL).

Methods: In 1,262 participants of the Netherlands Epidemiology of Obesity Study, a population-based cohort (age 45-65 years, 53% women, and median body mass index [BMI] 27 kg/m(2) ), knee OA was defined following modified American College of Rheumatology criteria. BMI and fat-free mass (as proxy for muscle mass) were assessed by bioelectrical impedance analysis, and comorbidities by self-report.