Effect of Comorbidity Burden on the Risk of Venous Thromboembolic Events After Total Knee Arthroplasty

BACKGROUND: Venous thromboembolic events (VTEs) are common after total knee arthroplasty (TKA). The rate of VTEs has improved with early mobilization, mechanical prophylaxis, and appropriate chemoprophylaxis. The aim of this study was to analyze the contribution of medical comorbidities to the risk of VTE after TKA METHOD: Medicare claims from 2005 to 2014 were queried. International Classification of Diseases, Ninth revision (ICD-9), and Current Procedural Terminology codes were used to identify the diagnoses, procedures, and complications. 157,200 primary TKAs were age, sex, and Elixhauser Comorbidity Index (ECI) matched with 157,200 osteoarthritis controls. First instances of deep venous thrombosis (DVT) and pulmonary embolism were tracked at 90 days and 2 years. Odds ratios (ORs), confidence intervals, and P-values (p) were calculated and used to investigate the contribution of comorbidities. RESULTS: 90 days after TKA or OA diagnosis, comorbidities were associated with 45% of the DVT risk, 38% of the PE risk. 1 in 92 patients would be expected to be diagnosed with VTE after TKA and 1 in 136 patients after only the diagnosis of osteoarthritis. After 90 days, medical comorbidities were associated with 70% of the DVT risk, 68% of the PE risk. CONCLUSION: Nearly 50% of DVTs and 40% of PEs within 90 days of TKA may be related to the baseline health of OA patients. Venous thromboembolic events after TKA are a “never” event according to Center of Medicare and services that appropriate VTE prophylaxis likely cannot be neutralized.