Introduction: Hospital-acquired infections (HAIs) present a global public health challenge, impacting patient safety and incurring substantial economic costs across healthcare settings. This study aims to accurately measure the financial burden of HAIs by analyzing real costs associated with various infections, providing insights for targeted prevention and management strategies. Methods: This retrospective cohort study at a university hospital in Rome, Italy, analysed Hospital Discharge Records (HDR) from January to December 2018, focusing on patients with and without HAIs. The study employed ICD-9-CM codes, microbiology databases, and stratified analyses by infection site and microorganism. Cost increments were calculated using DRG reimbursement data. Propensity score matching compared infected patients with matched non-infected counterparts, simulating a randomized trial through two models: one adjusting for length of stay and mortality (less conservative), and one not using these factors as confounders (more conservative). Results: In the study of 12,033 patients at Policlinico Universitario Tor Vergata, 10.07% developed an HAI, significantly raising mean DRG by 53.4% (<euro>3,744 to <euro>5,744). Propensity score analysis showed HAIs elevated costs by <euro>4,695 (60.45%) in one model, and by <euro>3,335 (31.15%) in another. Specific microbes and infection sites further influenced the cost impact, highlighting the need for targeted HAI prevention strategies. Conclusion: Our study reveals the significant economic impact of hospital-acquired infections (HAIs), with a substantial increase in costs linked to specific microorganisms and infection sites. These findings highlight the need for effective HAI prevention strategies to enhance patient safety and reduce healthcare expenditures.
