The utilization of primary total knee arthroplasty (TKA) in obese patients has increased significantly over the past decade despite overwhelming data that suggest higher failure rates. As such, it is reasonable to expect a parallel increase in obesity rates among revision TKA (rTKA) patients. The purpose of this study was to analyze longitudinal trends in obesity rates among rTKA patients.
We identified 451,982 rTKA patients using 2002-2012 Nationwide Inpatient Sample weighted discharge data. The Agency for Healthcare Research and Quality obesity comorbidity indicator was used to identify 70,470 obese patients (body mass index, >30) and 335,257 nonobese patients. We evaluated trends in obesity rates over time using chi-square tests and a multivariate logistic regression model, which included several covariates (patient age, gender, and race; payer type; hospital type; and patient health status).
The obesity rate among rTKA patients increased significantly from 9.74% in 2002 to 24.57% in 2012 (P < .0001). After adjusting for all factors, patients treated in 2011 (odds ratio [OR]: 4.1, 95% CI: 3.7-4.6, P < .0001) or 2012 (OR: 4.5, 95% CI: 4.0-5.0, P < .0001) were over 4 times as likely to be obese, compared to patients treated in 2002. Other independent factors that were significantly associated with higher obesity rates include female patients (OR: 1.5, 95% CI: 1.5-1.6) and patients between the ages of 45 and 64 years (OR: 3.2, 95% CI: 3.1-3.3).
The more than 4-fold increase in the obesity rate among patients undergoing rTKA, particularly the middle-age group, over the past decade is an alarming trend. Improved clinical care pathways are needed to manage the obese total knee patient.