Association Between Preoperative Anemia and the Risk of Revision After Total Knee Arthroplasty: A Multi-Institutional...

This study investigated the association between preoperative anemia and total knee arthroplasty (TKA) revision risk at a 3-year follow-up.

We conducted a multi-institutional retrospective cohort study of patients aged ≥b50 years who underwent primary TKA between 2010 and 2019 using a federated health research network database. Patients were categorized as anemic (hemoglobin eight to 12 g/dL) or nonanemic (≥ 12 g/dL), regardless of sex, and matched 1:1 using propensity scores. The primary outcome was TKA revision within 3 years; the secondary outcomes included periprosthetic joint infection (PJI), mortality, pneumonia, venous thromboembolism, and emergency department visit.

After matching (n = 6,477 per group), anemic patients had significantly higher risks of TKA revision (hazard ratio [HR]: 1.65, P < 0.0001), PJI (HR: 2.11, P < 0.0001), mortality (HR: 2.32, P < 0.0001), pneumonia (HR: 1.36, P = 0.0001), venous thromboembolism (HR: 1.35, P = 0.0006), and emergency department visits (HR: 1.11, P = 0.004) at the 3-year follow-up. Sensitivity analyses restricted to academic medical centers and excluding transfused patients confirmed these results. Even mild anemia (hemoglobin 10 to 12 g/dL) was associated with adverse outcomes. Subgroup analyses based on sex showed that men who had anemia demonstrated substantially higher risks for TKA revision (HR 2.09 versus 1.58 in women) and PJI (HR 3.51 versus 1.83 in women). A validation cohort of patients who underwent TKA during the COVID-19 pandemic (2020 to 2023) demonstrated consistently elevated risks of complications among anemic patients.

Preoperative anemia was independently associated with a statistically significant increase in the risks of TKA revision, PJI, mortality, and other adverse outcomes. This relationship was particularly pronounced in men. Preoperative anemia may be a modifiable risk factor for improved outcomes after TKA.