Abstract 177: The Burden of Sternal Wound Infections Following Coronary Artery Bypass Graft Surgery in Medicare Patients

Abstract

Objectives: Since 2008, the Centers for Medicare and Medicaid Services (CMS) have not reimbursed costs associated with sternal wound infections (SWI) that follow coronary artery bypass graft surgery (CABG). Beginning FY 2015, the Hospital-Acquired Condition (HAC) Reduction Program, mandated by the Affordable Care Act, requires the CMS to reduce hospital payments by 1 percent for hospitals that rank among the lowest-performing 25 percent with regard to HACs. SWI resulting from CABG was added to the program in FY 2016. The cost of treating SWIs is thus absorbed by the hospital, making optimized SWI prophylaxis an important part of hospital care. Here the burden of SWI following CABG in the Medicare population is calculated and the impact of improved prophylaxis quantified. Methods: Literature review identified publications presenting the incidence of surgical site infections (including superficial and deep SWIs), the time required to treat SWIs, and the costs of providing post CABG care. Key parameters to estimate the burden of SWIs were: CABG procedures per year, SWI rate, ratio of superficial to deep SWIs, length of stay, hospital time to treat SWIs, and the cost per day of intensive care unit (ICU) and general ward. A previously presented Markov model was adapted to estimate the yearly burden of SWIs after CABG procedures, with costs in 2016 USD. As antibiotic prophylaxis is essentially ubiquitous for patients undergoing CABG, data on other methods of reducing the SWI were considered. Single-patient-use electrocardiogram cable and lead (ECG) systems have recently been shown to significantly reduce the incidence of surgical site infection after CABG. The risk reduction at 30-days post CABG was 18.8% over reusable ECG. Results: The number of Medicare beneficiaries totals approximately 55.3 million people, with an annual rate of CABG of circa 178 procedures per 100,000 beneficiaries. Isolated CABG procedures under Medicare thus total 98,434. The SWI rate was reported to be between 1 and 4%, with deep SWI representing up to 40.75% of SWI cases. Using an SWI rate of 2.5% at 30 days, 20% of which are DSWI, indicated the burden of SWIs was $88.5 million. This included an additional 4,443 ICU and 21,443 general ward days, as well as over 1,000 readmissions. At the higher end of estimates, SWI could be costing providers $115.0 million. Assuming a 18.8% reduction in the SWI rate at 30 days, providers could save $12.6 million going up to $26.8 million ($271 per procedure) at the higher end of estimates. At a $6 incremental cost, single-patient-use ECG could represent a 45-fold return on investment. Conclusions: Superficial and deep SWIs after CABG procedures in the Medicare population come at considerable cost to providers. Preventing SWI has advantages for both patients and providers.