Fig. 1

Flowchart of registration. The medical records of patients who underwent influenza antigen testing during the study period were reviewed, and cases diagnosed with pneumonia or acute bronchitis in the emergency department were extracted. The classification of aspiration pneumonia and non-aspiration pneumonia was also based on the medical record entries. Cases in which the diagnosis recorded in the medical records changed during the subsequent clinical course were excluded. *Exclusion of cases in which the diagnosis recorded in the medical records changed during the subsequent clinical course. Abbreviations: AP, aspiration pneumonia; non-AP, pneumonia except for aspiration pneumonia; AB, acute bronchitis