A high α1-antitrypsin/interleukin-10 ratio predicts bacterial pneumonia in adults with community-acquired pneumonia: a prospective cohort study

Taiga Miyazaki; Kiyoyasu Fukushima; Kohji Hashiguchi; Shotaro Ide; Tsutomu Kobayashi; Toyomitsu Sawai; Kazuhiro Yatera; Yoshihisa Kohno; Yuichi Fukuda; Yoji Futsuki; Yuichi Matsubara; Hironobu Koga; Tomo Mihara; Eisuke Sasaki; Nobuyuki Ashizawa; Tatsuro Hirayama; Takahiro Takazono; Kazuko Yamamoto; Yoshifumi Imamura; Norihito Kaku; Kosuke Kosai; Yoshitomo Morinaga; Katsunori Yanagihara; Hiroshi Mukae

doi:10.1186/s41479-023-00118-4

A high α1-antitrypsin/interleukin-10 ratio predicts bacterial pneumonia in adults with community-acquired pneumonia: a prospective cohort study

Pneumonia (Nathan). 2023 Oct 25;15(1):16. doi: 10.1186/s41479-023-00118-4.

Authors

Taiga Miyazaki^{1

2}, Kiyoyasu Fukushima³, Kohji Hashiguchi⁴, Shotaro Ide^{5

6}, Tsutomu Kobayashi⁷, Toyomitsu Sawai⁸, Kazuhiro Yatera⁹, Yoshihisa Kohno¹⁰, Yuichi Fukuda¹¹, Yoji Futsuki¹², Yuichi Matsubara¹³, Hironobu Koga¹⁴, Tomo Mihara¹⁵, Eisuke Sasaki¹⁶, Nobuyuki Ashizawa⁵, Tatsuro Hirayama^{5

17}, Takahiro Takazono⁵, Kazuko Yamamoto^{5

18}, Yoshifumi Imamura^{5

19}, Norihito Kaku²⁰, Kosuke Kosai²⁰, Yoshitomo Morinaga^{20

21}, Katsunori Yanagihara²⁰, Hiroshi Mukae⁵

Affiliations

¹ Division of Respirology, Rheumatology, Infectious Diseases, and Neurology, Department of Internal Medicine, Faculty of Medicine, University of Miyazaki, Miyazaki, Japan. [email protected].
² Department of Respiratory Medicine, Nagasaki University Hospital, Nagasaki, Japan. [email protected].
³ Japanese Red Cross Nagasaki Genbaku Isahaya Hospital, Isahaya, Japan.
⁴ Japanese Red Cross Nagasaki Genbaku Hospital, Nagasaki, Japan.
⁵ Department of Respiratory Medicine, Nagasaki University Hospital, Nagasaki, Japan.
⁶ Isahaya General Hospital, Isahaya, Japan.
⁷ Sasebo Chuo Hospital, Sasebo, Japan.
⁸ Nagasaki Harbor Medical Center, Nagasaki, Japan.
⁹ Department of Respiratory Medicine, University of Occupational and Environmental Health, Japan, Kitakyushu, Japan.
¹⁰ Kouseikai Hospital, Nagasaki, Japan.
¹¹ Sasebo City General Hospital, Sasebo, Japan.
¹² Saiseikai Nagasaki Hospital, Nagasaki, Japan.
¹³ Juko Memorial Nagasaki Hospital, Nagasaki, Japan.
¹⁴ Aino Memorial Hospital, Unzen, Japan.
¹⁵ Nagasaki Medical Center, Omura, Japan.
¹⁶ Ureshino Medical Center, Ureshino, Japan.
¹⁷ Department of Pharmacotherapeutics, Nagasaki University Graduate School of Biomedical Science, Nagasaki, Japan.
¹⁸ First Department of Internal Medicine, Division of Infectious, Respiratory, and Digestive Medicine, University of the Ryukyus Graduate School of Medicine, Okinawa, Japan.
¹⁹ Medical Education Development Center, Nagasaki University Hospital, Nagasaki, Japan.
²⁰ Department of Laboratory Medicine, Nagasaki University Graduate School of Biomedical Sciences, Nagasaki, Japan.
²¹ Department of Microbiology, Graduate School of Medicine and Pharmaceutical Sciences, University of Toyama, Toyama, Japan.

Abstract

Background: Current microbiological tests fail to identify the causative microorganism in more than half of all pneumonia cases. We explored biomarkers that could be used for differentiating between bacterial and viral pneumonia in patients with community-acquired pneumonia (CAP).

Methods: In this prospective cohort study conducted in Japan, data obtained from adult patients with bacterial pneumonia, including bacterial and viral coinfections (bacterial pneumonia [BP] group), and purely viral pneumonia (VP group) at diagnosis were analyzed using multivariate logistic regression analysis to identify predictors of bacterial pneumonia. Furthermore, a decision tree was developed using the predictors.

Results: A total of 210 patients were analyzed. The BP and VP groups comprised 108 and 18 patients, respectively. The other 84 patients had no identified causative microorganism. The two groups shared similar characteristics, including disease severity; however, a significant difference (p < 0.05) was observed between the two groups regarding sputum type; sputum volume score; neutrophil counts; and serum levels of interleukin (IL)-8, IL-10, and α1-antitrypsin (AAT). Sputum volume score (p < 0.001), IL-10 (p < 0.001), and AAT (p = 0.008) were ultimately identified as predictors of BP. The area under the curve for these three variables on the receiver operating characteristic (ROC) curve was 0.927 (95% confidence interval [CI]: 0.881-0.974). The ROC curve for sputum volume score and an AAT/IL-10 ratio showed a diagnostic cutoff of 1 + and 65, respectively. Logistic regression analysis using dichotomized variables at the cutoff values showed that the odds ratios for the diagnosis of BP were 10.4 (95% CI: 2.2-50.2) for sputum volume score (absence vs. presence) and 19.8 (95% CI: 4.7-83.2) for AAT/IL-10 ratio (< 65 vs. ≥ 65).

Conclusions: Considering that obtaining a definitive etiologic diagnosis with the current testing methods is difficult and time consuming, a decision tree with two predictors, namely sputum volume and the AAT/IL-10 ratio, can be useful in predicting BP among patients diagnosed with CAP and facilitating the appropriate use of antibiotics.

Trial registration: UMIN000034673 registered on November 29, 2018.

Keywords: Bacterial pneumonia; Biomarker; Community-acquired pneumonia; Interleukin-10; α1-antitrypsin.