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.