Respiratory syncytial virus hospitalization outcomes and costs of full-term and preterm infants.

OBJECTIVE: Infection with respiratory syncytial virus (RSV), which causes lower respiratory tract infections, is the leading cause of hospitalization among children <1 year old in the United States. Risk factors for RSV hospitalization include premature birth and younger chronologic age, along with several comorbid conditions. However, in terms of RSV hospitalization costs, premature infants are rarely studied separately from full-term infants. The objective of this study is to describe the cost and severity of RSV hospitalizations among preterm and full-term infants without chronic lung disease or other high-risk conditions.

STUDY DESIGN: This analysis used Truven Health Market Scan Multi-State Medicaid and Commercial Claims and Encounters databases, which contain a combined 4 million births from 2003 to 2013. Infants with comorbid conditions associated with increased risk for RSV infection were excluded. Infants were classified as preterm (<29, 29-30, 31-32, 33-34 and 35-36 weeks' gestational age (wGA)) or full term based on diagnostic coding. Health-care claims during the first year of life were evaluated for RSV hospitalizations, defined as inpatient claims with a diagnosis code for RSV in any position. Costs of RSV hospitalizations were captured and reported in 2014 USD. Inpatient claims for RSV hospitalizations were evaluated for the presence of codes indicating admission to the intensive care unit (ICU), use of mechanical ventilation (MV) and length of stay. These three measures were used to describe hospital severity. Chronologic age at the time of RSV hospitalization was also captured. Data were summarized and no statistical comparisons were conducted.

RESULTS: There were 1 683 188 infants insured through Medicaid and 1 663 832 infants insured through commercial plans born from 1 July 2003 to 30 June 2013. Of those, 10.8 and 8.8% in each database, respectively, were born prematurely. There were 29 967 Medicaid-insured infants and 16 310 commercially insured infants with an RSV hospitalization during their first year of life. Mean first-year RSV hospitalization costs were higher for preterm infants, ranging from $8324 and $10 570 for full-term infants to $15 839 and $19 931 for preterm infants 33-34 wGA, and to $39 354 and $40 813 for preterm infants <29 wGA, among Medicaid-insured and commercially insured infants, respectively. RSV hospitalizations also tended to be more severe among preterm infants, with longer lengths of stay, a higher proportion of infants admitted to the intensive care unit (ICU) and increased use of MV compared with full-term infants. Mean costs of RSV hospitalizations with a PICU admission ranged from approximately $35 000 to $89 000. In both Medicaid and commercial groups, costs were greater for infants hospitalized at <90 days of age compared with older infants.

CONCLUSIONS: Infants who were born prematurely and those hospitalized at <90 days of age have more costly and more severe RSV hospitalizations during the first year of life. These findings demonstrate important differences in the costs and severity of first-year RSV hospitalizations of premature and full-term infants. These differences are likely to be obscured in combined analysis, in which full-term infants predominate. Clinical guidelines and health-care policies relating to RSV would benefit from the availability of data obtained from separate analyses of these two infant subgroups.