Pneumonia Caused by Severe Acute Respiratory Syndrome Coronavirus 2 and Influenza Virus: A Multicenter Comparative Study

Oi, Issei; Ito, Isao; Hirabayashi, Masataka; Endo, Kazuo; Emura, Masahito; Kojima, Toru; Tsukao, Hitokazu; Tomii, Keisuke; Nakagawa, Atsushi; Otsuka, Kojiro; Akai, Masaya; Oi, Masahiro; Sugita, Takakazu; Fukui, Motonari; Inoue, Daiki; Hasegawa, Yoshinori; Takahashi, Kenichi; Yasui, Hiroaki; Fujita, Kohei; Ishida, Tadashi; Ito, Akihiro; Kita, Hideo; Kaji, Yusuke; Tsuchiya, Michiko; Tomioka, Hiromi; Yamada, Takashi; Terada, Satoru; Nakaji, Hitoshi; Hamao, Nobuyoshi; Shirata, Masahiro; Nishioka, Kensuke; Yamazoe, Masatoshi; Shiraishi, Yusuke; Ogimoto, Tatsuya; Hosoya, Kazutaka; Ajimizu, Hitomi; Shima, Hiroshi; Matsumoto, Hisako; Tanabe, Naoya; Hirai, Toyohiro

BACKGROUND: Detailed differences in clinical information between severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pneumonia (CP), which is the main phenotype of SARS-CoV-2 disease, and influenza pneumonia (IP) are still unclear. METHODS: A prospective, multicenter cohort study was conducted by including patients with CP hospitalized between January and June 2020 and a retrospective cohort of patients with IP hospitalized from 2009 to 2020. We compared the clinical presentations and studied the prognostic factors of CP and IP. RESULTS: Compared with the IP group (n=66), in the multivariate analysis, the CP group (n=362) had a lower percentage of patients with underlying asthma or chronic obstructive pulmonary disease (p<0.01), lower neutrophil-to-lymphocyte ratio (p<0.01), lower systolic blood pressure (p<0.01), higher diastolic blood pressure (p<0.01), lower aspartate aminotransferase levels (p<0.05), higher serum sodium levels (p<0.05), and more frequent multilobar infiltrates (p<0.05). The diagnostic scoring system based on these findings showed excellent differentiation between CP and IP (area under the receiver operating characteristic curve, 0.889). Moreover, the prognostic predictors were different between CP and IP. CONCLUSIONS: Comprehensive differences between CP and IP were revealed, highlighting the need for early differentiation between these two pneumonias in clinical settings.