ILD O-012 : Scoring System to Diagnose Acute Eosinophilic Pneumonia Without Bronchoscopy

Purpose Acute eosinophilic pneumonia (AEP) is common among military personnel with smoking habits. Although its progression is rapid, bronchoscopy is mandatory for diagnosis which is sometimes difficult to perform immediately. Therefore, we aim to derive and validate a scoring system that could discriminate AEP from pneumonia without bronchoscopy. Methods Among patients hospitalized to Armed Forces Capital Hospital from November 15th 2016 to December 25th 2019, those diagnosed as either pneumonia or AEP while smoking were selected. Patients who fulfilled the Modified Philit’s criteria were categorized as AEP, and those diagnosed as pneumonia were categorized as pneumonia. Patients were divided into derivation and validation cohorts according to their admission dates. Demographics, comorbidities, symptoms, laboratory, and computed tomography findings were considered candidates for score derivation. Least absolute shrinkage and selection operator (LASSO) analysis was used to select and calculate coefficients of each variable. Coefficients were transformed into scores, and the score’s discrimination performance was calculated by area under the receiver operating characteristics curve (AUROC). Results Among the total of 414 patients, 279 and 135 were allocated to the derivation and validation cohorts, respectively. AEP was confirmed in 72 (17.4%), while 342 (82.6%) were diagnosed as pneumonia. With LASSO, ten variables were selected with corresponding scores: recent (<1 month) initiation of smoking or increase in smoking amount (7), interlobar septal thickening (5), ground glass opacity (2), bronchovascular bundle thickening (2), bilateral involvement (2), leukocytosis (2), dyspnea (2), chest pain (2), lack of sputum (2), and onset within 3 days (1). AUROC of the scoring system was 0.996 (95% confidence interval 0.991-1.000) in the derivation cohort, and 0.986 (95% confidence interval 0.967-1.000) in the validation cohort. Conclusions A scoring system that could discriminate AEP from pneumonia without bronchoscopy is introduced. This can aid in early diagnosis of AEP patients who cannot undergo urgent bronchoscopy.