Association Between Antibiotic Appropriateness and Clinical Outcomes in Patients with Urinary Tract Infection Using a Comprehensive Assessment: An Inverse Probability of Treatment Weighting-Adjusted Cohort Study

Background/Objectives: Evidence on the association between antibiotic appropriateness and clinical outcomes in urinary tract infection (UTI) remains inconsistent. We comprehensively evaluated the appropriateness of antibiotic therapy throughout the treatment course in patients with UTI and examined its association with clinical outcomes. Methods: Hospitalized patients with UTI at a Korean university-affiliated hospital were retrospectively reviewed. Appropriateness was assessed for antibiotic selection, dosage, route, and duration; patients in whom any component could not be assessed, including those who died within 3 days of antibiotic initiation, were excluded. Outcomes in complicated UTI were compared using inverse probability of treatment weighting (IPTW). Results: Of 629 patients, 94 had uncomplicated and 535 had complicated UTI. Overall appropriate therapy was more frequent in complicated UTI (77.2% vs. 27.7%). In-hospital mortality was 3.6% with appropriate and 4.1% with inappropriate therapy, and appropriate therapy was not associated with mortality after IPTW adjustment (adjusted odds ratio 1.31, 95% CI 0.43–4.01); length of stay, parenteral therapy duration, and antibiotic days of therapy did not differ. Conclusions: Comprehensively assessed appropriateness was not significantly associated with mortality or resource utilization in complicated UTI; however, the estimates were imprecise and compatible with both benefit and harm, and this finding should be regarded as exploratory. The administration route in uncomplicated UTI and treatment duration in both groups are stewardship targets, and the handling of unassessable cases can alter observed associations.