Characteristics of Outpatients Aged <65 Years Diagnosed with Nonbacterial Acute Infectious Diarrhea during Internal Medicine or Pediatric Clinic Consultation between 2019 and 2021 Based on a Large Japanese Medical Claims Database

This study aimed to clarify comorbid diseases diagnosed concurrently with nonbacterial acute infectious diarrhea following the 2019 revision of the Manual of Antimicrobial Stewardship, and to examine prescription patterns among outpatients who visited a clinic for this condition. We utilized a large Japanese medical claims database provided by IQVIA Japan. Between 2019 and 2021, outpatients aged <65 years who visited an internal medicine or pediatric clinic and were diagnosed with nonbacterial acute infectious diarrhea were selected. Patient characteristics, diseases diagnosed in the same month as that of nonbacterial acute infectious diarrhea, and prescriptions were investigated. Overall, 22590 patients were included in this analysis. Among the 5643 patients (25.0%) who received antibiotic prescriptions, acute bronchitis, acute pharyngitis, and pharyngitis were frequently reported simultaneously with nonbacterial acute infectious diarrhea. The antibiotic prescription rate was lowest among patients aged <6 years (internal medicine, 19.2%; pediatrics, 9.9%), compared with those aged 6-14 years (internal medicine, 25.0%; pediatrics, 14.4%) and 15-64 years (internal medicine, 28.5%; pediatrics, 26.2%). Notably, some patients diagnosed with nonbacterial acute infectious diarrhea also had comorbid conditions that required antibiotic use. Therefore, when assessing the appropriateness of antibiotic prescriptions, it is essential to consider these comorbidities. Furthermore, continued implementation of antimicrobial resistance countermeasures against nonbacterial acute infectious diarrhea remains important.