Heart Surgery Infections Vary Sharply by Hospital, Costing Medicare Millions

Where an American patient undergoes heart surgery may shape their recovery in ways that extend far beyond the operating room. A new study led by researchers at Michigan Medicine, the academic medical center of the University of Michigan, has found that the risk of developing an infection in the months after cardiac surgery varies more than twofold across United States hospitals, even after accounting for differences in patient health and the types of procedures performed. The analysis, published in The Journal of Thoracic and Cardiovascular Surgery, estimates that if hospitals with average or elevated infection rates could match the performance of the best-performing centers, roughly 2,600 infections could be prevented each year and Medicare spending could fall by as much as $441 million annually.

The scale of that figure becomes clearer when placed in context: $441 million approaches nearly twelve percent of the proposed fiscal year 2027 budget for the National Heart, Lung, and Blood Institute, the federal agency that funds much of the nation’s cardiovascular research. In other words, the money currently absorbed by preventable postoperative infections in a single insurance program rivals a substantial share of what the country invests in studying heart disease itself. The researchers argue that this gap represents not an intractable clinical challenge but a national opportunity to improve recovery and lower costs simultaneously.

To reach these conclusions, the team examined Medicare claims from nearly 240,000 cardiac surgery procedures carried out at approximately 1,000 hospitals between 2018 and 2023. Claims data allowed the investigators to track which patients were diagnosed with, and treated for, different categories of infection during the 180 days following their operations. This window matters because the danger of infection after cardiac surgery does not end at hospital discharge. About one in five patients develops an infection in the months following the procedure, with urinary tract infections, pneumonia, and sepsis among the most common complications. Sepsis, the body’s runaway inflammatory response to infection, is particularly consequential, since it can cascade into organ dysfunction and prolonged intensive care.

The study’s central finding is the sheer width of the variation. Hospitals in the highest infection group experienced more than twice as many infections as the best-performing institutions, a difference that persisted after the researchers statistically adjusted for differences in the patients each hospital treated and the procedures each performed. That adjustment is critical, because it addresses the most common objection to hospital comparisons: that some centers simply take on sicker, higher-risk patients. The persistence of the gap suggests that institutional factors, including surgical technique, perioperative protocols, antibiotic timing, wound care practices, and post-discharge monitoring, play a decisive role in outcomes.

The consequences of elevated infection rates ripple well beyond the infections themselves. Hospitals with higher infection rates also recorded higher rates of stroke, hospital readmission, and death up to six months after surgery. The financial toll was equally striking: procedures performed at hospitals in the highest infection group were associated with nearly $16,000 more in Medicare spending during the six months after surgery than identical procedures performed at hospitals in the lowest infection group. That figure captures not only the direct cost of treating infections but the downstream expenses of extended admissions, additional procedures, rehabilitation, and repeat hospitalizations that complications set in motion.

Using benchmark modeling, a technique that projects what would happen if all institutions performed at the level of the top performers, the research team estimated the national savings potential. Bringing hospitals with average and high infection rates in line with the best performers could prevent about 2,600 infections per year and reduce annual Medicare spending by as much as $441 million. Benchmarking of this kind is widely used in quality improvement research because it frames performance gaps not as a criticism of individual hospitals but as a measurable, addressable distance between current practice and demonstrated best practice.

One of the study’s more sobering discoveries concerns where these infections are actually detected. More than one-quarter of postsurgical infections were identified when patients were readmitted to a hospital different from the one where their surgery took place. The researchers point to this pattern as evidence of fragmented care. When patients receive follow-up treatment across multiple healthcare systems, their complete medical history may not travel with them, making complications harder to prevent, recognize, and manage in time. An infection brewing in a surgical wound may be caught late, or its early warning signs may be missed entirely by clinicians who did not perform the original operation and lack access to its details.

The findings echo earlier work by some members of the same research group. A previous study found that better care coordination for patients undergoing coronary artery bypass grafting, the heart bypass operation commonly known as CABG, could save an estimated $130 million annually in hospital readmission costs alone. Taken together, the two studies sketch a consistent picture: the recovery period after cardiac surgery is a vulnerable interval in which the quality of transitions between hospitals, clinics, and home care determines both patient outcomes and financial costs. Co-senior author Donald S. Likosky, the Richard and Norma Sarns Research Professor in Michigan Medicine’s Department of Cardiac Surgery, emphasized that a combination of hospital-based prevention strategies and effective transitions of care throughout the recovery period is needed to close the gap.

Co-senior author Francis Pagani, the Otto Gago MD Endowed Professor in Cardiac Surgery at the University of Michigan Medical School, framed the variation as a roadmap rather than an indictment. By understanding where practice patterns differ, he noted, researchers can better identify what drives the best outcomes and apply those approaches more broadly, providing consistent, high-quality care for every patient regardless of which hospital they enter. Co-first author Ahmad M. Hider, a National Clinician Scholar at the University of Michigan Institute for Healthcare Policy and Innovation and a general surgery resident at the University of Colorado, described reducing infections after cardiac surgery as a national opportunity to improve recovery and lower Medicare spending, underscoring the need to understand why some hospitals achieve better results and how best practices can be disseminated across the country.

The study was supported by the Agency for Healthcare Research and Quality, and the authors acknowledged the support of the Michigan Society of Thoracic and Cardiovascular Surgeons Quality Collaborative along with Blue Cross and Blue Shield of Michigan and Blue Care Network, which participate in the BCBSM Value Partnerships program. Additional contributors included co-first author Reem Nasser, a University of Michigan undergraduate and member of Michigan Medicine’s Undergraduate Research Academy, along with Chiang-Hua Chang, Shiwei Zhou, Thomas M. Braun, Robert B. Hawkins, Geoffrey D. Barnes, Michael P. Thompson, Timothy C. Guetterman of the University of Michigan, and Russell J. Funk of the University of Minnesota. As an observational study, the analysis identifies associations rather than proving causation, and the authors note that their conclusions do not reflect the views of AHRQ or the Department of Health and Human Services. Still, the message for patients, clinicians, and policymakers is difficult to ignore: the difference between a smooth recovery and a complicated one after heart surgery may depend as much on where the operation is performed and how care is coordinated afterward as on the surgery itself.

Subject of Research: Hospital variation in postoperative infections and Medicare spending after cardiac surgery in the United States

Article Title: Reducing infections after heart surgery could save Medicare $441 million per year

Article References: Reducing infections after heart surgery could save Medicare $441 million per year. (n.d.). Original publication

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Keywords: cardiac surgery, postoperative infection, Medicare spending, hospital quality variation, sepsis, pneumonia, care coordination, hospital readmission, benchmarking, health policy, coronary artery bypass grafting, patient outcomes