Nonsignificant lower risk for posttraumatic knee osteoarthritis
Similar to the published study, the OARSI poster compared 5-year odds of incident osteoarthritis or total knee replacement surgery between patients taking metformin and those taking sulfonylureas, but it focused on younger patients, aged 18-40 years, who underwent anterior cruciate ligament or meniscus surgery.
Using data from MarketScan commercial insurance claims databases between 2006 and 2020, the authors identified 2,376 participants who were taking metformin or a sulfonylurea when they underwent their surgery or began taking it in the 6 months after their surgery. More than half the participants were female (57%) with an average age of 35.
Within 5 years, 10.8% of those taking metformin developed osteoarthritis, compared with 17.9% of those taking a sulfonylurea. In addition, 3% of those taking metformin underwent a total knee replacement, compared with 5.3% of those taking a sulfonylurea. After adjustment for age, sex, obesity, and a history of chronic kidney disease, liver disease, and depression, however, both risk difference and odds ratios were not statistically significant.
Risk of osteoarthritis was 17% lower in patients taking metformin (95% confidence interval, –0.18 to 0.09), whose odds of osteoarthritis were approximately half the odds of those taking a sulfonylurea (OR, 0.5; 95% CI, 0.21-1.67). Risk of a total knee replacement was 10% lower in metformin users (95% CI, –0.28 to 0.08) with a similar reduction in odds, compared with those taking a sulfonylurea (OR, 0.53; 95% CI, 0.2-1.44).
In this study, the researchers did not specifically determine whether the participants were diagnosed with diabetes, but they assumed all, or at least most, were, according to S. Reza Jafarzadeh, PhD, DVM, an assistant professor of medicine at Boston University.
“The goal was not to only focus on the diabetes population, but on people who received that exposure [of metformin or sulfonylureas],” Dr. Jafarzadeh said in an interview. Dr. Jafarzadeh noted that a larger randomized controlled trial is underway to look at whether metformin reduces the risk of osteoarthritis independent of whether a patient has diabetes.
The published study was funded by grants from the National Institutes of Health, the Department of Veterans Affairs, and Stanford University, and the authors reported no disclosures. The poster at OARSI was funded by NIH and the Arthritis Foundation, and the authors reported no disclosures.