Characteristics and Outcomes of Patients in the ICU With Respiratory Syncytial Virus Compared With Those With Influenza Infection: A Multicenter Matched Cohort Study

BACKGROUND: The characteristics and outcomes of adult patients with respiratory syncytial virus (RSV) infection who require ICU admission are poorly defined. Although several studies in adults with RSV infection have been published in recent years, they did not focus specifically on patients with critical illness. RESEARCH QUESTION: What are the characteristics and outcomes of adult patients in the ICU with RSV infection and how do they compare with those of patients in the ICU with influenza infection? STUDY DESIGN AND METHODS: This retrospective, multicenter study in France and Belgium (17 sites) compared the characteristics and outcomes of adult patients in the ICU with RSV infection vs those with influenza infection between November 2011 and April 2018. Each patient with RSV infection was matched by institution and date of diagnosis with a patient with influenza infection. In-hospital mortality was compared between the two groups, with adjustment for prognostic factors in a multivariate model (sex, age, main underlying conditions, and concurrent bloodstream infection). RESULTS: Data from 618 patients (309 with RSV infection and 309 with influenza infection) were analyzed. Patients with RSV infection were significantly more likely to have an underlying chronic respiratory condition (60.2% vs 40.1%; P < .001) and to be immunocompromised (35% vs 26.2%; P = .02) than patients with influenza infection. Several differences in clinical signs and biological data at diagnosis were found between the groups. In-hospital mortality was not significantly different between the two groups (23.9% in the RSV group vs 25.6% in the influenza group; P = .63), even after adjustment for prognostic factors in amultivariate model. INTERPRETATION: Adult patients in the ICU with RSV infection differ from adult patients in the ICU with influenza in terms of comorbidities and characteristics at diagnosis. RSV infection was associated with high in-hospitalmortality, approaching 25%. Inmultivariate analysis, RSV-infection was associated with a similar odds of in-hospital death compared with influenza infection.