Background: Japan has a higher incidence of drug-induced interstitial pneumonia (IP) than other countries. Understanding the clinical characteristics of drug-induced IP in Japan will facilitate accurate diagnosis of the disease. The aim of this study was to analyze and report the clinical characteristics of drug-induced IP in Japan.
Methods: We analyzed the characteristics of drug-induced IP diagnosed between 2009 and 2022 in Japan. Case data were collated with the cooperation of pharmaceutical companies, as requested by the Ministry of Health, Labour and Welfare.
Results: We identified 285 patients with drug-induced IP diagnosed in medical institutions. The most common causative drugs identified were antineoplastic agents (56.1 %). Common subjective symptoms included dyspnea (158 patients [55.4 %]), cough (132 patients [46.3 %]), and fever (115 patients [40.4 %]). In addition, 177 patients (73.1 % of those measured) showed elevated serum KL-6, SP-D, or SP-A levels. Approximately 60 % of the patients developed IP within 90 days from the initiation of drug therapy, whereas 15 % developed the disease after >1 year. Regarding imaging findings, 249 patients (87.4 %) showed bilateral shadows. Corticosteroid therapy was administered to 222 patients (77.9 %). The treatment outcomes of drug-induced IP in Japan were favorable, with improvement observed in 273 patients (95.8 %).
Conclusions: Dyspnea, cough, and fever after administration of a drug; elevated serum KL-6, SP-D, and SP-A levels; and bilateral shadows were identified as clinical features of drug-induced IP in Japan. Drug-induced IP should be considered a differential diagnosis even if the patient started using the causative drug long ago.
Keywords: Adverse event; Antineoplastic agents; Drug-induced interstitial pneumonia; Drug-induced lung disease; Lung injury.
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