Hospitalized intensive care patients with respiratory syncytial virus were significantly more likely to be immunocompromised and to have chronic respiratory conditions than those with influenza infections, but in-hospital mortality rates were similar, based on data from 618 adults.
Respiratory syncytial virus is common in adults, but characteristics of RSV patients requiring ICU care have not been explored, despite routine testing for RSV in critically ill patients in many institutions, Julien Coussement, PhD, of Université Libre de Bruxelles, Brussels, and colleagues wrote.
“Influenza is another respiratory virus routinely tested for in ICU patients with respiratory symptoms because of its well-known morbidity and mortality, but there are no data specifically comparing RSV and influenza infections in adult ICU patients,” they noted.
In a retrospective, multicenter study published in the journal CHEST, the researchers analyzed data from 309 adult ICU patients with RSV infection and 309 with influenza infection between November 2011 and April 2018 from 17 sites in France and Belgium. Each RSV patient was matched to a flu patient according to institution and date of diagnosis.
The primary objective was a comparison of in-hospital mortality between the groups, defined as death from any cause during an index hospital stay in acute care. Secondary objectives were comparisons of the clinical and biological characteristics of patients with RSV versus flu.
Overall, in-hospital mortality was not significantly different between the RSV and influenza groups (23.9% vs. 25.6%, P = .63).
However, patients with RSV infection were significantly more likely than those with flu to have an underlying chronic respiratory condition (60.2% vs. 40.1%, P < .001) and to be immunocompromised (35% vs. 26.2%, P = .02). Very few of the patients overall (39 patients, 6.3%) were considered young and healthy prior to hospitalization; and significantly fewer of these were in the RSV group than in the influenza group (9 patients and 30 patients, respectively).
Airway obstruction at the time of diagnosis was significantly more common in the RSV patients than in influenza patients (49.5% vs. 39.5%, P = .01), but influenza patients were significantly more likely to have acute respiratory distress syndrome at the time of diagnosis (21.7% vs. 14.6%, P = .02). Rates of coinfections were similar between the groups, and approximately 60% of coinfected patients received at least 72 hours of therapeutic antibiotics. Overall length of hospital stay, ICU stay, and duration of mechanical ventilation were similar between the groups.
The results show that severe RSV occurs mainly in older patients with comorbidities, and these results reflect data from previous studies, the researchers wrote in their discussion. In addition, “patients with influenza infection were significantly more likely to have fever, myalgia, increased CPK level, thrombocytopenia and transaminitis at diagnosis than were those with RSV infection. Whether these differences may be used to guide patient management remains to be determined.”
The study findings were limited by several factors including the retrospective design, and testing for respiratory viruses on symptomatic patients only, rather than all ICU patients, the researchers noted. Other limitations include the inability to show a causal link between viral infections and patient outcomes and the heterogenous management of patients among different centers.
However, the results were strengthened by the large sample size and multivariate analysis, and support the need for interventions to prevent and treat severe RSV, they concluded.
The study received no outside funding. Lead author Dr. Coussement disclosed serving on advisory board for Sanofi.