Effect of palivizumab prophylaxis in decreasing respiratory syncytial virus hospitalizations in premature infants.
BACKGROUND
Respiratory syncytial virus (RSV) is a major cause of hospitalization in preterm infants and infants with chronic lung disease (CLD). Palivizumab, a humanized monoclonal antibody, was approved in Europe in 1999 as prophylaxis against severe RSV-related respiratory illness. No multiple season data have been published on palivizumab effectiveness in European populations. Data collected during 4 years in Spain compared RSV hospitalization rates and risk factors in a cohort of palivizumab-prophylaxed and nonprophylaxed preterm infants.


METHODS
The first cohort was derived from 2 previous studies and included 1583 infants followed during 2 RSV seasons (1998 to 1999, 1999 to 2000) before palivizumab initiation in Spain. The second cohort included 1919 infants who received palivizumab prophylaxis for 2 subsequent respiratory seasons (2000 to 2001, 2001 to 2002). Both cohorts were preterm (< or =32 weeks gestational age) and < or =6 months old at onset of RSV season.


RESULTS
The RSV hospitalization rate in the palivizumab-prophylaxed cohort was 3.95, and it was 13.25% in nonprophylaxed infants This 70% overall difference in RSV hospitalization was observed despite the palivizumab-prophylaxed group's lower gestational ages, more severe neonatal intensive care unit respiratory courses and higher incidence of CLD. Significant risk factors for RSV hospitalization in both cohorts included: lower gestational age; chronologic age <3 months at RSV season onset; school age siblings; and lower parental education. Nonprophylaxed children had a higher risk for RSV-related hospitalization than did prophylaxed patients (odds ratio, 3.86; 95% confidence interval, 2.83 to 5.25).


CONCLUSIONS
Data from this study support the effectiveness of palivizumab in significantly modifying RSV-related hospitalizations in high risk preterm infants, with and without CLD, during two respiratory seasons.
D000911:Antibodies, Monoclonal / Q000008:administration & dosage*; D061067:Antibodies, Monoclonal, Humanized; D000998:Antiviral Agents / Q000008:administration & dosage; D015331:Cohort Studies; D016001:Confidence Intervals; D004305:Dose-Response Relationship, Drug; D004334:Drug Administration Schedule; D005260:Female; D005500:Follow-Up Studies; D006760:Hospitalization / Q000706:statistics & numerical data* / Q000639:trends; D006801:Humans; D015994:Incidence; D007231:Infant, Newborn; D007234:Infant, Premature; D007363:Intensive Care Units, Neonatal / Q000706:statistics & numerical data; D008297:Male; D015999:Multivariate Analysis; D000069455:Palivizumab; D011322:Primary Prevention / Q000379:methods; D011336:Probability; D018357:Respiratory Syncytial Virus Infections / Q000188:drug therapy / Q000517:prevention & control*; D012189:Retrospective Studies; D018570:Risk Assessment; D013030:Spain; D018709:Statistics, Nonparametric; D016896:Treatment Outcome
D000911:Antibodies, Monoclonal; D061067:Antibodies, Monoclonal, Humanized; D000998:Antiviral Agents; D000069455:Palivizumab