Elizabeth Hofheinz, MPH, M.Ed.
With type 2 diabetes on the rise, a team of researchers from Emory University in Atlanta set out to find out how the diabetes drug metformin could affect knee replacement (TKA) outcomes. Their retrospective cohort study, “Metformin use is associated with fewer complications in patients with type 2 diabetes undergoing knee replacement,” appears in the April 7, 2021 issue of the Journal of Bone and Joint Surgery.
Co-author Jacob M. Wilson, MD, an Emory-based orthopedic surgeon, told OSN: “It is known that diabetes negatively affects the results after knee replacement. We were interested in how this increased risk can be changed. Metformin has been extensively studied in the medical literature but has not yet been studied in patients with endoprosthetics. Given that metformin is currently recommended for all patients with type II diabetes (except for those with chronic kidney disease where it is currently contraindicated), we felt it was important to determine the impact of metformin on results . “
Using the Truven MarketScan Commercial Claims and Encounters and Medicare Supplemental and Coordination of Benefits databases, the researchers identified adults who had primary unilateral TKA between 2009 and 2008 and who were diagnosed with type 2 diabetes preoperatively. They analyzed the 90 day results and also performed a subgroup analysis of the 1 year revision rates. A total of 64,372 patients were included in the analysis – 32,186 in the metformin group and the same in the no-metformin group.
“Outcomes and complication profiles after knee arthroplasty have improved over the past few decades,” he said DR. Wilson to OSN. “However, high-risk patient populations remain a challenge. Patients with diabetes are known to be at higher risk. While metformin is indicated in the treatment of almost all patients with type II diabetes, it is well documented that many of these patients are inappropriately prescribed the drug. If metformin improves the complication profiles in this patient population, it is important information for orthopedic surgeons to consider as it should be included in patient optimization protocols. “
Both the metformin cohort and the no-metformin cohort had similar baseline characteristics, with both a mean patient age of 64 years and a composition of 58% female patients. Not only that, the burden of comorbidity was similar, and the number of insulin-dependent patients and the number of patients taking other diabetic drugs were almost identical in each group.
When the researchers checked the baseline traits, they found that people who were not prescribed metformin were more likely to develop a 90-day periprosthetic joint infection, deep vein thrombosis, and acute kidney injury.
Dr. Wilson: “We looked at matching cohorts of patients with type II diabetes and found that those prescribed metformin were less likely to have a prosthetic joint infection and revision after one year. Patients on metformin were also found to be less likely to have readmission and early postoperative complications, including deep vein thrombosis. “
“Our study was retrospective. Future work should be done in the form of a prospective, randomized study. “
