Risk factors for knee osteoarthritis in Morocco. A case control study.

Osteoarthritis (OA) of the knee is the most common form of arthritis. A positive association between obesity and several occupational factors and knee OA has been observed in previous studies in populations of different ethnicity. The aim of this study was to examine the relation between knee OA and body weight and occupational factors in a Moroccan sample of patients with knee OA. Our cases were consecutive patients diagnosed in our department with knee OA utilizing radiography in a 1-year period. No cases displayed established causes of secondary OA. Controls were selected randomly from the general population and were individually matched to each case for age and sex. Interviews were obtained from 95 cases and controls. Detailed information on general health status, height, weight, smoking habits, specific physical loads from occupation and housework, and sports activities was collected. The risk of knee OA increased with higher body mass index, odds ratio (OR) = 3.12 (95% confidence interval [CI] = 1.67-5.81; p < 0.0001). Sitting more than 3 h/day and climbing stairs more than 50 steps/day were associated with decreased risk of knee OA, OR = 0.29 (95% CI = 0.15-0.56; p = 0.02) and 0.48 (95% CI = 0.26-0.91; p < 0.0001), respectively. Overweight is a risk factor for knee OA, whereas sitting and climbing stairs are inversely associated with knee OA.