304 Respiratory Syncytial Virus Hospitalization in Infants with Chronic Lung Disease: An 8-Year Retrospective National Hospital Survey

Aims: To determine trends in proportions of respiratory syncytial virus hospitalization (RSVH) over an 8-year time period beginning in 1998 when palivizumab was licensed in the United States using a retrospective cohort study of all hospitalized children < 2 years of age with chronic lung disease (CLD). Methods: Data from the United States National Hospital Discharge Survey (NHDS) were collected over an 8-year period (1998-2006). NHDS, a multistage systematic survey sample of US hospitals, provides yearly national estimates of inpatient hospital utilization. We defined RSVH using International Classification of Diseases, Ninth Edition (ICD9) codes of 079.6 (RSV), 466.11 (acute bronchiolitis due to RSV), and 480.1 (pneumonia due to RSV). Yearly proportions of RSVH assessed for children with CLD (defined by ICD9 code 770.7) were calculated between 1998 and 2006. Trends were described using linear regression. Results: There were 140,463 hospitalizations due to CLD identified between 1998 and 2006. The proportion of CLD RSVH is shown in the graph. A statistically significant (P=0.030) average decrease of 0.6% RSV hospitalizations per year among infants hospitalized with CLD was observed. Figure Conclusion: These results suggest a significant decrease in RSVH in infants with CLD between 1998 and 2006. The reasons for this decrease need further study but may include improved NICU and outpatient management of CLD, variation of RSV severity and the use of palivizumab in this high-risk population. Sponsored by MedImmune.