Risk factors for severe respiratory syncytial virus-associated lower respiratory tract infection in children

Background: Respiratory syncytial virus (RSV) is the most important cause of viral lower respiratory tract infection that can be a life-threatening disease in infants and children. This study was conducted to look for independent risk factors for severe respiratory syncytial virus-associated lower respiratory tract infection (RSV-LRI) that required oxygen supplementation or mechanical ventilation. Methods: Medical records of patients younger than 4 years hospitalized with RSV-LRI at Shizuoka Red Cross Hospital from July 1, 1995 to June 30, 1999 were reviewed. The patients were compared using univariate and multivariate logistic regression analysis. Results: A total of 157 patients were hospitalized with RSV-LRI at Shizuoka Red Cross Hospital from the study time period. Of these, 20 patients (12.7%) were diagnosed with severe RSV-LRI. Subjects younger than 3 months of age had an odds ratio (OR) of 59.9 (95% confidence interval (CI) 14.7-244.0) for the dependent variable of severe RSV-LRI (P < 0.0001). Subjects with a history of congenital heart disease also had an OR of 99.2 (95% C1 8.5-1160.1) (P < 0.0005). Conclusions: Infants younger than 3 months without any underlying diseases may be at high risk for severe RSV-LRI. Respiratory syncytial virus prophylaxis is needed not only for high-risk patients, but for healthy early infants.