PEDIATRIC INVESTIGATORS COLLABORATIVE NETWORK ON INFECTIONS IN CANADA (PICNIC) PROSPECTIVE-STUDY OF RISK-FACTORS AND OUTCOMES IN PATIENTS HOSPITALIZED WITH RESPIRATORY SYNCYTIAL VIRAL LOWER RESPIRATORY-TRACT INFECTION

Objective: To provide information on disease attributable to respiratory syncytial viral lower respiratory tract infection (RSV LRI) and to quantify the morbidity associated with various risk factors. Design: Prospective cohort study. Subjects: Patients hospitalized with RSV LRIs at seven centers were eligible for study if they were younger than 2 years of age, or hospitalized patients of any age if they had underlying cardiac or pulmonary disease or immunosuppression. Measurements and results: Enrolled (n = 689) and eligible but not enrolled (n = 191) patients were similar in age, duration of illness and proportion with underlying illness, use of intensive care, and ventilation. Of the enrolled patients, 156 had underlying illness. The isolates from 353 patients were typeable: 102 isolates were subgroup A, 250 were subgroup B, and one isolated grouped with both antisera. The mean hospital stay attributable to respiratory syncytial virus (RSV) was 7 days; 110 patients were admitted to intensive care units, 63 were supported by mechanical ventilation, and 6 patients died. Regression models were developed for the prediction of three outcomes: RSV-associated hospital duration,intensive care unit admission, and ventilation treatment. In addition to previously described risk factors for an increased morbidity, such as underlying illness, hypoxia, prematurity and young age, three other factors were found to be significantly associated with complicated hospitalization: aboriginal race (defined by maternal race), a history of apnea or respiratory arrest during the acute illness before hospitalization, and pulmonary consolidation as shown on the chest radiograph obtained at admission. The RSV subgroup, family income, and day care attendance were not significantly associated with these outcomes.