Influence of obesity on the development of osteoarthritis of the hip: a systematic review
Summary written by Kevin Fontaine, Ph.D.
Knee osteoarthritis (OA) is an increasingly prevalent chronic disease that is a major cause of pain, disability, and impaired quality of life in older adults. Obesity is a major risk factor for the development of knee OA and it also independently impairs quality of life. Although the American College of Rheumatology recommends weight reduction and exercise to assist in the management of knee OA, we do not know whether these lifestyle practices actually improve quality of life in persons with knee OA. Rejeski and colleagues (Health Psychology 21: 419-426, 2002.) conducted a randomized controlled clinical trial to examine the effects of weight loss and exercise on the quality of life of overweight and obese older adults with knee OA.
Methods: 316 overweight/obese older adults with clinical and radiographic evidence of knee OA were randomized to one of four 18-month interventions: (diet-only, exercise-only, diet and exercise, or health education control). Each intervention involved group meetings and detailed instruction to promote weight loss, increased exercise, or both. The control group participated in monthly meetings that emphasized health education and social interaction. The main outcome measure was quality of life, measured at baseline and at 6 and 18-months by the Medical Outcomes Study Short-Form 36 Health Survey (SF-36).
Results: Each intervention produced weight loss: diet-only (5.7% of body weight), exercise-only (2.6%), diet and exercise (4.4%), and controls (1.3%). Compared to controls, only the diet and exercise intervention produced a statistically significant improvement on physically-oriented domains of quality of life. Although non-significant, the other interventions (diet-only and exercise-only) also produced modest benefits compared to controls. The interventions did not produce significant benefits with regard to psychological domains of quality of life such as energy level, social functioning, or mental health.
Conclusions: A lifestyle intervention that promotes weight loss and exercise enhances the quality of life of overweight and obese, older adults with knee OA. The benefits, however, were restricted to physically-oriented domains of quality of life such as physical functioning, bodily pain, and general health perception.
Editorial Comments: This study suggests that promoting lifestyle modification among overweight and obese, older adults with knee OA produces considerable quality of life benefits on physical domains of functioning. That is, persons report that they are less impaired in their perceived capacity to engage in physical activities. Both the diet-only and exercise-only interventions also produced quality of life benefits, but their effects were more modest. It is important to note that this study was of relatively short-term duration and, thus, cannot address whether or not the quality of life benefits will be sustained in the long-term. Given the difficulty with maintaining health lifestyle practices over time, it is likely that both weight and physical activity levels will eventually revert back to their pre-intervention levels. Nonetheless, this study indicates that, at least in the short-term, knee OA patients can benefit greatly from lifestyle practices that promote weight control and physical activity.