Prevention of knee osteoarthritis - full scale trial
03 / 2008 - unknown
Primary research questions: 1) What is the preventive effectiveness of the tailor made strategy to reduce weight in a high risk group of overweight middle aged women on the development of knee osteoarthritis? 2) What is the preventive effectiveness of oral crystalline glucosamine sulphate in a high risk group of overweight middle aged women on the development of knee osteoarthritis? Secondary research questions: 4) Are there subgroups of women who have (better) effectiveness of one of the both interventions (e.g. women with pre-arthrotic features or processes measured with MRI/markers)? 5) Is it possible to decrease sample size or follow-up time in future preventive osteoarthritis trials when intermediate outcomes (MRI/markers) for knee osteoarthritis are used? The past decades, world wide research identified the major risk factors for developing osteoarthritis (OA) of the knee. The next important step in osteoarthritis research, also based on recent developments on intermediate outcome measures in OA, is to test preventive strategies in high-risk groupsOverweight is the major modifiable risk factor in knee OA. Overweight most often is caused by an unbalanced food intake in relation to physical activity, a way of life which is hard to change. To accomplish any change in such behavior, a "tailor made" intervention with diet and physical activity is the most successful. However, an intervention with oral crystalline glucosamine sulphate, a product with growing scientific evidence for its chondroprotective actions, is probably much more easy and feasible then the above-mentioned intervention. In this full scale randomized intervention study we will test the preventive effect of both interventions. The study population will comprise a high-risk group for knee OA of 400 overweight women aged 50-60 years who not yet have consulted for pain in the knee. In a randomized controlled trial with factorial design half of the women will be randomized to the tailor made intervention to reduce weight, the other half will not receive this intervention. Secondly, in both groups half of them will be randomized to receive oral crystalline glucosamine sulphate while the other half will receive a placebo. Both groups will be followed for two and a half years. The primary outcome measure after two and a half years is the difference between the intervention and control groups in occurrence of radiological knee osteoarthritis (Kellgren & Lawrence index 2 or more), and/or joint space narrowing of 1 mm or more in one of the knees during the follow-up time, and/or occurrence of a knee osteoarthritis according to the ACR criteria. Because OA is a gradually ongoing process and radiological OA features only are late derivatives of the processes in the joint, we will also measure intermediate outcomes (osteoarthrotic features measured on MRI, bone and collagen markers), giving a more direct insight in ongoing processes in and around the joint.