Long-term effects of a lifestyle intervention and oral glucosamine sulphate in primary care on incident knee OA in overweight women.

The present study was designed to evaluate the effect of a lifestyle intervention aimed to reduce body weight and of oral glucosamine sulphate on the incidence of knee osteoarthritis (OA) after 6-7 years in a population of middle-aged, overweight women, without knee OA at baseline.

The Prevention of knee Osteoarthritis in Overweight Females study, ISRCTN42823086, was a randomized controlled trial with a 2 × 2 factorial design. Four hundred and seven women aged 50-60 years with a BMI of ⩾27 kg/m 2 and free of knee OA were randomized.

Four hundred and seventy-seven knees from 245 participants were available after a mean follow-up time of 6.6 years. Nineteen per cent of all knees showed incident knee OA. Both interventions showed no significant preventive effect on incident knee OA. Despite the fact that per protocol analyses showed greater differences between both groups for the lifestyle intervention, significance was not reached. A significant effect of losing ⩾5 kg or ⩾ 5% of baseline weight in the first 12 months on the incidence of knee OA according to the primary outcome was found (odds ratio = 0.10; 95% CI: 0.02, 0.41).

No significant preventive effect on incident knee OA of either the lifestyle intervention or the glucosamine intervention was found. As a proof of concept, the preventive effect of moderate weight loss in 1 year on the incidence of clinical knee OA is demonstrated. This trial provides important insights for future studies on the prevention of knee OA, which are currently lacking.

ISRTCN registry, http://www.isrctn.com , ISRCTN42823086.