Does weight loss reduce the incidence of total knee and hip replacement for osteoarthritis?-A prospective cohort study among middle-aged and older adults with overweight or obesity.

OBJECTIVE

This study aims to investigate the association between weight change and total knee or hip replacement (TKR or THR) for OA among middle-aged and older adults with overweight or obesity.

METHOD

Weight data were collected in 2006-2009 and in 2010 from the 45 and Up Study-a population-based cohort aged ≥45 years in New South Wales, Australia. Participants were included if they had a baseline body mass index (BMI) ≥ 25 kg/m and no history of TKR or THR. Weight change was categorised into four groups: >7.5% loss; >5-7.5% loss; stable (≤5% change) and >5% gain. Hospital admission data were linked to identify TKR and THR for OA, and multivariable Cox regression was used to assess risk of TKR and THR.

RESULTS

Of 23,916 participants, 2139 lost >7.5% weight, 1655 lost 5-7.5% weight, and 4430 gained >5% weight. Over 5.2 years, 1009 (4.2%) underwent TKR and 483 (2.0%) THR. Compared to weight-stable, weight loss of >7.5% was associated with reduced risk of TKR after adjusting for age, sex, BMI, socioeconomic and lifestyle factors (hazard ratio 0.69, 95%CI 0.54-0.87), but had no association with THR. Weight loss of 5-7.5% was not associated with altered risk of either TKR or THR. Weight gain was associated with increased risk of THR after adjusting for confounders, but not TKR.

CONCLUSION

This study suggests that a weight loss target >7.5% is required to reduce the risk of TKR in adults with overweight or obesity. Weight gain should be avoided as it increases the risk of THR.