Clinical Factors Associated with Documented Radiographic Pneumonia in Adults with Human Metapneumovirus Infection: A Hospital-Wide Cohort Study in Japan
- 1Department of Respiratory Medicine, Kyorin University School of Medicine, 6-20-2 Shinkawa, Mitaka 181-8611, Tokyo, Japan
Abstract
Background/Objectives: Human metapneumovirus (hMPV) is increasingly recognized as an important cause of adult respiratory infection, but data on pneumonia remain limited. We evaluated clinical characteristics, temporal detection patterns, and clinical factors associated with radiographic pneumonia among adults with laboratory-confirmed hMPV infection. Methods: We conducted a single-center retrospective observational study at Kyorin University Hospital, Tokyo, Japan, from December 2020 to February 2026. Adults aged ≥18 years with hMPV detected by multiplex polymerase chain reaction were included. The primary outcome, documented radiographic pneumonia, was defined by newly identified pneumonia-compatible parenchymal abnormalities on chest radiography and/or chest computed tomography (CT). Logistic regression was used to identify clinical factors associated with this outcome. Results: Among 590 hMPV-positive patients, 192 adults were included; 121 were managed as outpatients and 71 were hospitalized. Pneumonia was identified in 68 adults, including 43 of 71 hospitalized patients. Adult hMPV detection shifted from summer predominance in 2022–2023 toward increased spring and winter detections in 2024–2025 after the onset of the coronavirus disease 2019 (COVID-19) pandemic. By 2025, pneumonia was identified in 24.0% of outpatients and 65.5% of hospitalized patients. In the primary multivariable model, higher C-reactive protein (CRP) concentrations (adjusted odds ratio per 1 mg/dL, 1.12; 95% confidence interval (CI), 1.03–1.22; p = 0.008) and abnormal auscultation (adjusted odds ratio, 3.45; 95% CI, 1.21–9.83; p = 0.021) were independently associated with pneumonia. Conclusions: Adult hMPV infection was frequently associated with radiographic pneumonia, particularly among hospitalized patients. Elevated C-reactive protein concentrations and abnormal auscultation may help identify adults with hMPV infection who are more likely to have pneumonia.
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BibTeX
@article{saraya2026clinical,
title = {{Clinical Factors Associated with Documented Radiographic Pneumonia in Adults with Human Metapneumovirus Infection: A Hospital-Wide Cohort Study in Japan}},
author = {Takeshi Saraya and Junki Tashiro and Hajime Furuno and Yoshitaka Sakamoto and Kei Nakajima and Sho Yamada and Takatora Akizawa and Narishige Ishikawa and Hiromi Ishida and Tatsuya Shirai and Jumpei Aso and Nozomi Kurokawa and Fumi Kobayashi and Yasuo Nakamoto and Manabu Ishida and Mitsuru Sada and Keitaro Nakamoto and Saori Takata and Haruyuki Ishii},
journal = {Journal of Clinical Medicine},
year = {2026},
month = oct,
doi = {10.3390/jcm15208025},
url = {https://www.mdpi.com/2077-0383/15/20/8025},
note = {CC BY 4.0},
}
RIS
TY - JOUR
TI - Clinical Factors Associated with Documented Radiographic Pneumonia in Adults with Human Metapneumovirus Infection: A Hospital-Wide Cohort Study in Japan
AU - Takeshi Saraya
AU - Junki Tashiro
AU - Hajime Furuno
AU - Yoshitaka Sakamoto
AU - Kei Nakajima
AU - Sho Yamada
AU - Takatora Akizawa
AU - Narishige Ishikawa
AU - Hiromi Ishida
AU - Tatsuya Shirai
AU - Jumpei Aso
AU - Nozomi Kurokawa
AU - Fumi Kobayashi
AU - Yasuo Nakamoto
AU - Manabu Ishida
AU - Mitsuru Sada
AU - Keitaro Nakamoto
AU - Saori Takata
AU - Haruyuki Ishii
PY - 2026
DA - 2026/10/16
JO - Journal of Clinical Medicine
DO - 10.3390/jcm15208025
UR - https://www.mdpi.com/2077-0383/15/20/8025
AB - Background/Objectives: Human metapneumovirus (hMPV) is increasingly recognized as an important cause of adult respiratory infection, but data on pneumonia remain limited. We evaluated clinical characteristics, temporal detection patterns, and clinical factors associated with radiographic pneumonia among adults with laboratory-confirmed hMPV infection. Methods: We conducted a single-center retrospective observational study at Kyorin University Hospital, Tokyo, Japan, from December 2020 to February 2026. Adults aged ≥18 years with hMPV detected by multiplex polymerase chain reaction were included. The primary outcome, documented radiographic pneumonia, was defined by newly identified pneumonia-compatible parenchymal abnormalities on chest radiography and/or chest computed tomography (CT). Logistic regression was used to identify clinical factors associated with this outcome. Results: Among 590 hMPV-positive patients, 192 adults were included; 121 were managed as outpatients and 71 were hospitalized. Pneumonia was identified in 68 adults, including 43 of 71 hospitalized patients. Adult hMPV detection shifted from summer predominance in 2022–2023 toward increased spring and winter detections in 2024–2025 after the onset of the coronavirus disease 2019 (COVID-19) pandemic. By 2025, pneumonia was identified in 24.0% of outpatients and 65.5% of hospitalized patients. In the primary multivariable model, higher C-reactive protein (CRP) concentrations (adjusted odds ratio per 1 mg/dL, 1.12; 95% confidence interval (CI), 1.03–1.22; p = 0.008) and abnormal auscultation (adjusted odds ratio, 3.45; 95% CI, 1.21–9.83; p = 0.021) were independently associated with pneumonia. Conclusions: Adult hMPV infection was frequently associated with radiographic pneumonia, particularly among hospitalized patients. Elevated C-reactive protein concentrations and abnormal auscultation may help identify adults with hMPV infection who are more likely to have pneumonia.
SN - 2077-0383
ER -