Bronchiolitis-associated hospitalizations among US children, 1980-1996

Context Respiratory syncytial virus (RSV) causes more lower respiratory tra ct infections, often manifested as bronchiolitis, among young children than any other pathogen. Few national estimates exist of the hospitalizations a ttributable to RSV, and recent advances in prophylaxis warrant an update of these estimates. Objectives To describe rates of bronchiolitis-associated hospitalizations a nd to estimate current hospitalizations associated with RSV infection. Design and Setting Descriptive analysis of US National Hospital Discharge S urvey data from 1980 through 1996. Participants Children younger than 5 years who were hospitalized in short-s tay, nonfederal hospitals for bronchiolitis. Main Outcome Measure Bronchiolitis-associated hospitalization rates by age and year. Results During the 17-year study period, an estimated 1.65 million hospital izations for bronchiolitis occurred among children younger than 5 years, ac counting for 7.0 million inpatient days. Fifty-seven percent of these hospi talizations occurred among children younger than 6 months and 81 % among th ose younger than 1 year. Among children younger than 1 year, annual bronchi olitis hospitalization rates increased 2.4-fold, from 12.9 per 1000 in 1980 to 31.2 per 1000 in 1996. During 1988-1995, infant hospitalization rates f or bronchiolitis increased significantly (P for trend <.001), while hospita lization rates for lower respiratory tract diseases excluding bronchiolitis did not vary significantly (P for trend = .20). The proportion of hospital izations for lower respiratory tract illnesses among children younger than 1 year associated with bronchiolitis increased from 2.2% in 1980 to 47.4% i n 1996; among total hospitalizations, this proportion increased from 5.4% t o 16.4%, Averaging bronchiolitis hospitalizations during 1994-1996 and assu ming that RSV was the etiologic agent in 50% to 80% of November through Apr il hospitalizations, an estimated 51 240 to 81 985 annual bronchiolitis hos pitalizations among children younger than 1 year were related to RSV infect ion. Conclusions During 1980-1996, rates of hospitalization of infants with bron chiolitis increased substantially, as did the proportion of total and lower respiratory tract hospitalizations associated with bronchiolitis. Annual b ronchiolitis hospitalizations associated with RSV infection among infants m ay be greater than previous estimates for RSV bronchiolitis and pneumonia h ospitalizations combined.