Metformin Linked to Lower Risk of Total Joint Replacement in Older Adults

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A retrospective analysis of more than 40,000 patients suggests use of metformin was associated with a significant reduction in total joint replacements among a cohort of aging adults.

Comparing data from 20,000 patients treated with metformin and 20,000 patients treated without metformin, results of the study suggest adherence to metformin was associated with a 30% reduction in risk of total knee or total hip replacement.

"We found that metformin use in patients with type 2 diabetes mellitus was associated with a significantly reduced risk of joint replacement, suggesting a potential therapeutic effect of metformin in patients with osteoarthritis," said Changhai Ding, Clinical Research Center of Zhujiang Hospital, Southern Medical University, Guangzhou, China, in a statement.

As populations across the globe begin to age, a better understanding of optimization practices for overall health and well-being of older patients becomes of the utmost importance. With this in mind, Ding and a team of colleagues from institutions in Taiwan, China, and Australia designed the current research endeavor to explore whether metformin use was associated with a reduced risk of total knee replacement or total hip placement.

To do so, the investigators’ analyses leveraged the Taiwan National Health Insurance Research database to identify patients with type 2 diabetes diagnosed between 2000-2012. A total of 85,455 participants with a new diagnosis of type 2 diabetes were identified for potential inclusion. Using prescription time-distribution matching, a total of 20,347 participants who were not treated with metformin and 20,347 participants treated with metformin for inclusion in their analyses. This cohort had a mean age of 63 (SD, 11) years and 49.8% were women.

For further analysis, investigators used propensity-score matching to identify 10,163 matched pairs of metformin users and nonusers. Investigators planned to use Cox proportional hazards regression to estimate associations of metformin use with risk of total knee replacement or total hip replacement as a composite and as individual end points.

Upon analysis, results indicated found use of metformin was associated with a lower risk of total knee replacement or total hip replacement (aHR, 0.70 [95% CI, 0.60-0.81]). When assessing individual components of the primary end point results demonstrated use of metformin was associated with a reduction in risk for both total knee replacement (aHR, 0.71 [95% CI, 0.61-0.84]) and total hip replacement (aHR, 0.61 [95% CI, 0.41-0.92]). Investigators pointed out similar trends were observed in In propensity-score matching and sensitivity analyses using inverse probability of treatment weighting and competing risk regression.

“Given our findings and those of a previous observational study, a randomized trial of the efficacy of metformin in patients with [osteoarthritis] is indicated,” wrote investigators.

This study, “Metformin use and associated risk of total joint replacement in patients with type 2 diabetes: a population-based matched cohort study,” was published in the Canadian Medical Association Journal.