Hospitalization Costs Attributable to Antimicrobial Resistance in Spain: A Nationwide Cohort Study.

BACKGROUND: Antimicrobial resistance (AMR) is a major global health threat with substantial clinical and economic consequences. However, robust national estimates of the economic burden of AMR-related hospitalizations to AMR remain limited. We aimed to quantify the hospitalization costs attributable to AMR in Spain and to assess their variation across infection types. METHODS: We conducted a nationwide, retrospective cohort study using the Spanish Specialized Care Activity registry (RAE-CMBD). We included all adult hospitalizations with a diagnosis of bacterial infection between Jan 1, 2017, and Dec 31, 2022. AMR was defined using ICD-10-CM resistance diagnosis codes.Hospitalization costs were estimated using nationally standardized APR-DRG cost weights. Generalized linear models were used to estimate the incremental cost associated with AMR after adjustment for demographic and clinical characteristics. RESULTS: Among 2,817,406 hospitalizations with bacterial infection, 175,188 (6.22%) involved AMR. In adjusted analyses, AMR was associated with a 15% increase in hospitalization costs (cost ratio 1.15, 95% CI 1.15-1.16; p<0.0001), corresponding to an incremental cost of EUR 925 (95% CI 887-962) per hospitalization.The cost of hospitalizations with bacterial AMR infections was EUR 215 million annually (95% CI 213.33-216.67). After adjustment for patient and clinical characteristics, the attributable economic burden of AMR was EUR 27.10 million annually. This economic impact of AMR varied substantially across infection types, with the greatest attributable economic burden intra-abdominal infections, acute pyelonephritis, pneumonia, and lower urinary tract infections. CONCLUSIONS: In this nationwide cohort, AMR was independently associated with an increase in hospitalization costs in Spain, contributing meaningfully to national healthcare expenditure.