Clinical and cost outcomes of venous thromboembolism in Medicare patients undergoing total hip replacement or total knee replacement surgery.

BACKGROUND: Venous thromboembolism (VTE) occurs most often during hospitalization for major surgery or trauma but may also occur up to several months after surgery. Since the potential for VTE exists in a range of clinical settings, an assessment of its impact on overall outcomes and costs to the patient and to the healthcare system is warranted.
OBJECTIVE: To evaluate the effects of VTE (deep vein thrombosis, pulmonary embolism, or both) occurring within the first 30 days of hospital discharge for total hip replacement (THR) or total knee replacement (TKR) surgery on inpatient costs, mortality, rehospitalization, and major bleeding within 1 year after initial hospitalization for THR or TKR surgery.
METHODS: The Medicare Provider Analysis and Review (MEDPAR) file for calendar years 2005-2007 provided hospital discharge abstracts for the fee-for-service, acute-care hospitalizations of all Medicare recipients. All patients included in the analysis underwent THR (n = 51,108) or TKR (n = 115,627). VTE events were diagnosed within the first 30 days and within 1 year post discharge. Propensity score matching was used to control for differences in baseline characteristics in patients with and without VTE events. Total cost was measured as Medicare cost plus beneficiary out-of-pocket cost.
RESULTS: VTE occurred in 0.74% of patients undergoing THR. For patients with VTE versus no VTE, mortality was higher (2.9% vs 0.4%, P < 0.001) and rehospitalization within 1 year was more frequent (51.9% vs 22.4%, P < 0.001), as were complications such as bleeding (11.2% vs 2.7%, P < 0.001). Risk-adjusted Medicare cost and total healthcare cost, including beneficiary cost share in 1 year, were significantly higher for VTE patients versus patients with no VTE ($18,929 vs $3763, P < 0.001). VTE occurred in 0.70% of patients undergoing TKR. For patients with VTE versus no VTE, mortality was higher (2.5% vs 0.15%, P < 0.001), and rehospitalization within 1 year was more frequent (48.7% vs 20.7%, P < 0.001), as were complications such as bleeding (13.7% vs 2.1%, P < 0.001). For TKR surgery, risk-adjusted total healthcare cost, including beneficiary cost share in 1 year, was significantly different for VTE versus no VTE ($17,996 vs $4358, P < 0.001). LIMITATIONS: Study limitations include a reliance on ICD-9-CM codes, which could be inaccurate, and the inability (1) to control for unmeasured confounders, such as surgeons' skills; (2) to include outpatient medical care costs; and (3) to ensure that all patients were enrolled continuously throughout the study period.
CONCLUSIONS: VTE after THR or TKR is associated with higher mortality, rehospitalization, and bleeding within 1 year, compared with no VTE. Risk-adjusted total, Medicare, and beneficiary healthcare costs were significantly higher for both THR and TKR patients with VTE (P < 0.001).