Introduction: Urinary tract infections (UTI) are the second most common type of infection in older adults, and serious cases can lead to hospitalization, with severe complications like kidney failure and sepsis. Meanwhile, antibacterial resistance is on the rise, which can impact the severity of hospitalizations and clinical outcomes, as well as hospital costs. In this study, we explore the costs and characteristics associated with UTI hospitalizations with and without multi-drug resistance (MDR). Methods: Using the Healthcare Cost and Utilization Project (HCUP) National Inpatient Sample (NIS), a longitudinal database of inpatient visits in the United States (US), we conducted a retrospective study of UTI hospitalizations from 2012-2019. Among inpatient visits with UTI as a primary diagnosis, we further examined those with ICD-9 and ICD-10 codes of multi-drug resistance. Demographics associated with inpatient visits were collected, and hospital costs were inflation-adjusted to 2022 US dollars. In addition, we fitted a linear regression model on the variables of sex, race, payment type, length of stay, and age. Results: From 2012 to 2019, the study found an approximately weighted estimate of 23,810 records of UTI hospitalizations, and among those, 595 (2.5%) records had some form of multi-drug resistance. Among UTI records, the mean cost was $7766 and the mean length of stay (LOS) was 4 days. Among UTI with MDR records, the mean cost was $9902 and the mean LOS was 4.8 days. The average cost of UTI hospitalizations increased by 10.2% from 2012 to 2019. Surprisingly, the cost of UTI hospitalizations in multi-drug resistant patients decreased by 45% over this time span. Results from the linear regression model from UTI inpatient visits show that lower costs were most strongly associated with White race (p < 0.001), Black race (p < 0.001), while higher costs were associated with Asian/Pacific Islander race (p < 0.001) and LOS (p < 0.001). The linear regression model from UTI with MDR records showed lower costs most robustly correlated with White race (p < 0.05), while LOS (p < 0.0001) and female sex (p < 0.05) correlated with higher costs. Conclusions: This study found that mean cost of UTI inpatient visits was higher in those with MDR than no MDR. Overall costs have increased over time, and several demographics were associated with varying costs. Future studies should more closely examine the costs associated with MDR and more complicated sequelae of UTIs. SOURCE OF Funding: N/A
