Hospitalization rates for respiratory syncytial virus infection in premature infants born during two consecutive seasons

Objective. To collect data on hospitalization rates for respiratory syncytial virus (RSV) illness during the season of 1999 to 2000 in nonprophylaxed premature infants less than or equal to 32 weeks gestational age (GA) in Spain and compare this with previously published data collected in the season of 1998 to 1999. Methods. Children born at less than or equal to 32 weeks GA between April 1, 1999, and April 31, 2000, and discharged from the hospital before April 31, 2000, were included. Neonatal and demographic data were obtained at the initial visit. Study subjects were followed at monthly intervals throughout the respiratory season. RSV status and morbidity data were collected on patients rehospitalized for respiratory illness. Results. The 999 evaluable patients in the 2000 season were comparable to the 1999 sample, except for higher rates of family allergy history and number of multiple deliveries and a lower rate of neonatal morbidity. The hospitalization rate for RSV illness was 13.4% in the 1999 season and 13.1% in the 2000 season; 10 (8%) were RSV reinfections in the 2000 season. Significant independent prognostic variables for high risk of RSV hospital admission included: lower gestational age; chronologic age <3 months at onset of the RSV season; living with school age siblings; and exposure to tobacco smoke. Conclusions. Hospitalization rates for RSV disease in nonprophylaxed preterm infants less than or equal to 32 weeks GA were high in Spain and comparable during two consecutive RSV seasons (13%). Readmission for a second RSV infection was also common.