Clinical significance of respiratory virus detection in patients with acute exacerbation of interstitial lung diseases

Background: The impact of viral infections on acute exacerbations in idiopathic pulmonary fibrosis ( IPF) and/or non-IPF interstitial lung disease ( ILDs) has been scarcely described. Objectives: To elucidate the frequency of virus infections in patients with IPF or non-IPF ILDs including idiopathic interstitial pneumonia ( IIP) or connective tissue disease ( CTD)-associated pneumonia, and its influence on their short-term mortality. Methods: We prospectively enrolled adult patients with acute exacerbation of IPF and non-IPF ILDs who were admitted to the hospital during the last 3 years, and examined the respiratory samples obtained from nasopharyngeal, sputum, and bronchoalveolar lavage fluid. Results: A total of 78 patients were identified, consisting of 27 patients with acute exacerbation of IPF and 51 patients with non-IPF ILDs ( IIP: n=27, CTD-associated IP: n=24). Of all patients, 15 ( 19.2%) had viruses detected in their respiratory samples including the human herpesvirus 7 ( HHV7; n=4) and cytomegalovirus ( CMV) plus HHV7 ( n=3). The proportion of virus infections in the IPF and non-IPF ILDs groups was comparable. The Kaplan-Meier survival curves over 60 days revealed a lower survival probability in the virus positive group ( n=15, 60%) than in the virus negative group ( n=60, 83.3%, p < 0.05). However, the virus infection itself could not predict the 60-day survival probability using simple logistic regression analysis. Conclusions: Viral infections, mostly CMV or HHV7, were identified in both patients with acute exacerbation of IPF and non-IPF ILDs, but the clinical significance on short-term mortality or isolation itself from respiratory samples remains to be determined.