Outcomes of severe human metapneumovirus-associated community-acquired pneumonia in adults

Background: The outcomes of severe human metapneumovirus (HMPV)-associated pneumonia have not been adequately evaluated. Objectives: We aimed to investigate the incidence and outcomes of severe HMPV-associated CAP and to compare them with those of severe IFV associated CAP. Study design: From March 2010 to August 2017, all consecutive adult patients with severe HMPV-associated CAP and severe influenza virus (IFV)-associated CAP who required intensive care unit admission were prospectively identified and followed in a 2,700-bed tertiary care hospital. The characteristics and outcomes of severe HMPV-associated CAP patients were compared with those of severe IFV-associated CAP patients. Results: HMPV and IFV were identified in 3.2% (50) and 7.0% (109) of the 1559 patients with severe CAP, respectively. The mortality rates were not significantly different between the HMPV and IFV groups (30-day mortality: 24.0% vs. 32.1%, p = 0.30; 60-day mortality: 32.0% vs. 38.5%, p = 0.43). Oral ribavirin therapy was not associated with improved outcome (60-day mortality: ribavirin therapy group 35.0% [7/20] vs. no ribavirin therapy group 30.0% [9/30], p = 0.71). Subgroup analyses showed no significant differences in mortality among non-immunocompromised (60-day mortality: HMPV 25.6% vs. IFV 31.1%, p = 0.55) and immunocompromised patients (60-day mortality; HMPV 54.5% vs. 54.3%, p = 0.99). The length of ICU and hospital stay did not differ between groups. Conclusions: The incidence of HMPV infection was approximately half that of IFV infection in a cohort of patients with severe CAP. The mortality rate of severe HMPV-associated CAP was similar to that of severe IFV associated CAP.