Clinical Features and Outcomes of IPF Patients Hospitalized for Pulmonary Infection: A Japanese Cohort Study

Many patients with idiopathic pulmonary fibrosis (IPF) undergo hospitalizations due to pulmonary infections. We retrospectively investigated the characteristics of hospitalizations due to pulmonary infection in patients with IPF to elucidate causative pathogens and mortality. We reviewed patients with IPF who were admitted between January 2008 and December 2014 for pulmonary infections including pneumonia and bronchitis. The causative pathogen, the relationship between the site of pneumonia and existing IPF radiological patterns on high-resolution chest CT, and predictors of mortality were evaluated. Forty-eight IPF patients were hospitalized a totally of 81 times due to pulmonary infection during the study period. In the 48 first-time admissions after IPF diagnosis, causative pathogens were detected in 20 patients (41.6%). The most common pathogen was Haemophilus influenzae (14.5%) followed by Pseudomonas aeruginosa (4.1%), Staphylococcus aureus (4.1%), Branhamella catarrhalis (4.1%), and Klebsiella pneumoniae (4.1%). Among all 81 admissions, the most common pathogen was P. aeruginosa (12.3%), followed by H. influenzae (8.6%), S. aureus (6.1%) and Escherichia coli (4.9%). No relationship was observed between the detected pathogen and the site of pneumonia. The 30-day and hospital mortality rates were 14.5% and 18.7%, respectively. Pneumonia severity index on admission was significantly associated with both 30-day and hospital mortality. In conclusion, IPF patients hospitalized for pulmonary infections had high 30-day and hospital mortality. In contrast to community-acquired pneumonia, the causative pathogens mainly consisted of gram-negative bacteria. The PSI score may be a significant predictor of mortality. These results provide information for empiric antibiotic selection when treating IPF patients with pulmonary infections.