A Novel Method for Stratification of 30-Day Major Complication Risk Using Body Mass Index Thresholds for Patients Undergoing Total Knee Arthroplasty: A National Cohort of 443,157 Patients

Background: Many organizations have used pre-established body mass index (BMI) cut-offs to guide surgical decision-making. As there have been many improvements in patient optimization, surgical technique, and perioperative care over time, it is important to reassess these thresholds and contextu-alize them to total knee arthroplasty (TKA). The purpose of this study was to calculate data-driven BMI thresholds that predict significant differences in risk of 30-day major complications following TKA.Methods: Patients who underwent primary TKA from 2010 to 2020 were identified in a national data-base. Stratum-specific likelihood ratio (SSLR) methodology was used to determine data-driven BMI thresholds at which the risk of 30-day major complications increased significantly. These BMI thresholds were tested using multivariable logistic regression analyses. A total of 443,157 patients were included, who had a mean age of 67 years (range, 18 to 89 years), mean BMI of 33 (range 19 to 59), and 11,766 (2.7%) patients had a 30-day major complication.Results: SSLR analysis identified four BMI thresholds that were associated with significant differences in 30-day major complications: 19 to 33, 34 to 38, 39 to 50, and 51 thorn . When compared to those who had a BMI between 19 and 33, the odds of sustaining a major complication sequentially and significantly increased by 1.1, 1.3, and 2.1 times (P < .05 for all) for the other thresholds.Conclusion: This study identified four data-driven BMI strata using SSLR analysis that were associated with significant differences in the risk of 30-day major complications following TKA. These strata can be used to guide shared decision-making in patients undergoing TKA.& COPY; 2023 Elsevier Inc. All rights reserved.