Background: There is uncertainty about the burden of hospitalization associated with respiratory syncytial virus (RSV) and influenza in children, including those with underlying medical conditions.
Methods: We applied previously developed methodology to Health Care Cost and Utilization Project hospitalization data and additional data related to asthma diagnosis/previous history in hospitalized children to estimate RSV and influenza-associated hospitalization rates in different subpopulations of US children between 2003 and 2010.
Results: The estimated average annual rates (per 100,000 children) of RSV-associated hospitalization with a respiratory cause (ICD-9 codes 460-519) present anywhere in the discharge diagnosis were 2,381 (95% CI(2252,2515)) in children <1 year of age; 710.6 (609.1, 809.2) (1 y old); 395 (327.7, 462.4) (2 y old); 211.3 (154.6, 266.8) (3 y old); 111.1 (62.4, 160.1) (4 y old); 72.3 (29.3, 116.4) (5-6 y of age); 35.6 (9.9,62.2) (7-11 y of age); and 39 (17.5, 60.6) (12-17 y of age). The corresponding rates of influenza-associated hospitalization were lower, ranging from 181 (142.5, 220.3) in <1 year old to 17.9 (11.7, 24.2) in 12-17 years of age. The relative risks for RSV-related hospitalization associated with a prior diagnosis of asthma in age groups <5 y ranged between 3.1 (2.1, 4.7) (<1 y old) and 6.7 (4.2, 11.8) (2 y old; the corresponding risks for influenza-related hospitalization ranged from 2.8 (2.1, 4) (<1y old) to 4.9 (3.8, 6.4) (3 y old).
Conclusion: RSV-associated hospitalization rates in young children are high and decline rapidly with age. There are additional risks for both RSV and influenza hospitalization associated with a prior diagnosis of asthma, with the rates of RSV-related hospitalization in the youngest children diagnosed with asthma being particularly high.