Factors predicting life-threatening infections with respiratory syncytial virus in adult patients

Respiratory syncytial virus (RSV) is a significant cause of acute respiratory illness with a clinical spectrum ranging from self-limiting upper respiratory infection to severe lower respiratory infection in elderly persons as well as young children. However, there are limited data on risk factors for life-threatening infections that could guide the appropriate use of antiviral agents in adult patients with RSV.We conducted a retrospective cohort study from October 2013 to September 2015. Adult patients with RSV who visited the emergency department were enrolled. Primary outcome was life-threatening infection (admission to intensive care unit, need for ventilator care or in-hospital death).A total of 227 patients were analysed. Thirty-four (15%) were classified as having life-threatening infections. By logistic regression, lower respiratory infection, chronic lung disease and bacterial co-infection were independent predictors of life-threatening infections. We developed a simple clinical scoring system using these variables (lower respiratory tract infection = score 4, chronic respiratory disease = score 3, bacterial co-infection = score 3 and fever ≥38 °C = score 2) to predict life-threatening infection. A score of5 differentiated life-threatening RSV from non-life-threatening RSV with 82% sensitivity (95% CI, 66-93) and 72% specificity (95% CI, 65-78).The use of a clinical scoring system based on lower respiratory infection, chronic respiratory disease, bacterial co-infection and fever appears to be useful for outcome prediction and risk stratification in order to select patients who may need early antiviral therapy.