Infections After Heart Surgery Drive Up Costs, and Payment Groups Show Where

Hospital-acquired infections remain one of the most consequential complications of cardiac surgery, and a new study from China now puts a sharper economic point on that problem. Researchers at the First Affiliated Hospital of Soochow University analyzed two years of clinical data from cardiovascular surgery patients and found that the financial damage inflicted by a nosocomial infection is not uniform across procedure types. Instead, the burden varies dramatically depending on the diagnosis-related group, or DRG, into which a patient falls, a finding with direct implications for how hospitals are paid and how they allocate scarce infection-control resources.

The study, published in BMC Infectious Diseases, examined cardiovascular surgery patients treated between January 2023 and December 2024. The overall prevalence of nosocomial infection in this population was 12.27 percent, a figure that underscores how common these complications are in a surgical specialty where patients often undergo open-chest procedures, receive mechanical ventilation, and carry multiple comorbidities. Yet the headline number conceals a striking heterogeneity. When the researchers stratified patients by DRG, infection rates ranged from comparatively low figures in some groups to nearly four in ten patients in others.

The highest burden appeared in the coronary artery surgery group designated FC19, where 39.57 percent of patients acquired a nosocomial infection. Heart valve surgery, grouped under FB29, followed with a rate of 34.49 percent, while complicated operations on the great vessels, coded FE19, saw infections in 31.09 percent of cases. These are not marginal differences from the overall average; they represent subgroups in which roughly one in three patients experienced an infection during hospitalization, an order of magnitude that demands targeted rather than generic prevention strategies.

Methodologically, the study tackled a persistent challenge in health economics research: infected and uninfected patients differ systematically in ways that bias simple cost comparisons. Patients who develop infections tend to be sicker at baseline, undergo longer operations, and stay in intensive care longer before the infection even appears. To address this, the investigators employed propensity score matching or inverse probability of treatment weighting within each DRG subgroup, techniques that statistically balance the comparison groups on observed characteristics. This design allowed them to isolate the additional costs attributable to infection itself, rather than to the underlying severity of illness.

The microbiology added another layer of concern. Klebsiella pneumoniae emerged as the most common pathogen in the study population, a finding consistent with the growing global prominence of gram-negative organisms in hospital-acquired infections. The researchers also tracked drug-resistant threats within their framework, referencing carbapenem-resistant Acinetobacter baumannii, methicillin-resistant Staphylococcus aureus, and carbapenem-resistant Pseudomonas aeruginosa as categories of concern. The dominance of Klebsiella is particularly notable given the rising prevalence of extended-spectrum beta-lactamase-producing and carbapenem-resistant strains of this organism worldwide, which complicates empirical antibiotic choices and raises both treatment costs and clinical risk.

The dominant infection type was equally striking. Non-ventilator-associated lower respiratory tract infections accounted for 90.57 percent of nosocomial infections in the cohort. That such a large share of infections involved the lower airways without being attributable to ventilator use points to a distinct pathophysiological and operational problem. Cardiac surgery patients arrive in the postoperative period with anesthesia-related respiratory depression, pain-limited coughing, immobility, and often preexisting pulmonary compromise, all of which create fertile conditions for pneumonia even after ventilators are removed. Prevention efforts aimed solely at ventilator bundles may therefore miss the bulk of the respiratory infection burden in this population.

The economic analysis quantified what those infections cost. Among patients in the heart valve surgery group FB29, a non-ventilator-associated lower respiratory tract infection significantly increased total hospitalization costs, with a cost ratio of 1.17, meaning infected patients incurred costs roughly 17 percent higher than statistically comparable uninfected peers, at a confidence interval of 1.01 to 1.36 and a P value of 0.037. More consistent effects appeared in the medicine cost category. Infections raised medication expenses by 50 percent in the FB29 valve surgery group, 27 percent in the FE19 great vessel group, and 30 percent in the FC19 coronary artery group, with all confidence intervals excluding unity and P values below 0.05.

One of the study’s most important conclusions is that the primary drivers of infection-attributable expenses differed across DRG groups. In some groups the excess costs flowed through pharmaceutical spending, reflecting prolonged or escalated antibiotic therapy and supportive medications. In others, longer intensive care stays, additional diagnostic testing, or extended ward admissions played larger roles in inflating total hospitalization costs. This granularity matters because it tells hospital administrators and infection-control teams not just that infections are expensive, but where in the cost structure those expenses accumulate for each category of cardiac operation.

The DRG lens is central to the study’s relevance for health policy. Under DRG-based payment systems, hospitals receive a fixed, prospectively determined payment per case grouped by diagnosis and procedure complexity. When a patient acquires an infection and costs rise, much of the additional expense is absorbed by the hospital rather than reimbursed, converting preventable infections from a payer problem into a direct institutional financial liability. The study’s findings suggest that hospitals performing high volumes of valve surgery, coronary artery procedures, or great vessel operations face particularly concentrated exposure, and that infection prevention in these DRGs functions as economic self-protection as much as clinical stewardship.

The authors conclude that further research is urgently needed to identify clinically recognizable, infection-related risk factors specific to each DRG, work that would enable precise infection management and better-informed resource allocation. In the interim, the study offers a template: rather than treating all cardiac surgical patients as a single population, hospitals can use DRG stratification to identify which procedure groups carry the highest infection risk, which pathogens dominate, and which cost categories bear the brunt of each preventable infection. As diagnostic-related group payment systems spread globally, that kind of subgroup-specific evidence is likely to become the standard against which infection-control investment is judged.

Subject of Research: Economic burden of nosocomial infections in cardiovascular surgery patients analyzed by DRG payment groups

Article Title: Direct economic burden of nosocomial infection in cardiovascular surgery patients based on DRG payment management

Article References: Wang, Y., Song, X., Jin, M., & Dong, Q. (2026). Direct economic burden of nosocomial infection in cardiovascular surgery patients based on DRG payment management. BMC Infectious Diseases. https://doi.org/10.1186/s12879-026-14448-3

Image Credits: AI Generated

DOI: 10.1186/s12879-026-14448-3

Keywords: nosocomial infection, cardiovascular surgery, diagnosis-related groups, lower respiratory tract infection, hospital costs, Klebsiella pneumoniae, health economics, cardiac surgery, infection control, DRG payment, hospital-acquired pneumonia, cost ratio