Kong et al: Increased RSV hospitalizations in the 2014-2015 season vs the 2013-2014 season1

A study examining RSV hospitalizations in preterm and full-term infants across the 2013-2014 and 2014-2015 RSV seasons

Study Design

Data Source

MarketScan Commercial Claims and Multistate Medicaid databases

Patient Selection Criteria

Infants born between July 1, 2009, and June 30, 2015

Included

  • Preterm infants born 29-36 wGA
  • Full-term infants without health problems

Commercially insured, n=1.0 million

Medicaid-insured, n=1.2 million

Excluded

  • Preterm and full-term infants with CLDP, CHD, or other special conditions, such as: Cystic fibrosis Immunodeficiency Congenital anomalies of respiratory system Neuromuscular, immunological, or genetic conditions Organ transplants

Outcomes Evaluated

  • RSV hospitalizations that occurred ≥2 days after birth hospitalization discharge were examined using the following ICD-9-CM codes:

RSV infection (079.6)

RSV bronchiolitis (466.11)

RSV pneumonia (480.1)

  • Absolute rates were defined as the hospitalization rate per 100 infant-seasons

Study Limitations

  • RSV hospitalizations were identified using ICD-9-CM diagnosis codes on inpatient claims. Confirmatory laboratory results were not available, as claims databases typically lack these measures
  • RSV may be undercoded given that RSV testing is not generally recommended
  • The increased rates of all-cause bronchiolitis hospitalization in infants 29-34 wGA in 2014-2015 demonstrate that there was an overall increase in bronchiolitis hospitalizations, regardless of whether they were coded as RSV
  • Despite using 2 large databases, there were small numbers of infants in some groups, leading to wide CIs and limiting the statistical power to detect differences between seasons
  • The use of hospitalization rates among non–high-risk full-term infants as a reference group may not have fully addressed the potential variation in RSV season severity

RSV Hospitalization Rates

RSV hospitalization rates significantly increased in commercially insured preterm infants 29-34 wGA and <3 months CA in the 2014-2015 season vs the 2013-2014 season

   
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Graph showing number of RSV-related hospitalizations among commercially-insured infants by gestational age and RSV season (2013-2014 vs. 2014-2015). 

RSV hospitalization rates significantly increased in Medicaid-insured preterm infants 29-34 wGA and <3 months CA in the 2014-2015 season vs the 2013-2014 season

   
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Graph showing number of RSV-related hospitalizations among commercially-insured infants by gestational age and RSV season (2010-2014 vs 2014-2015). 

Summary

Kong et al conclusions:

  • RSV hospitalization rates significantly increased in commercially insured and Medicaid-insured preterm infants 29-34 wGA and <3 months CA in the 2014-2015 season vs the 2013-2014 season
  • ~3x greater in commercially insured infants
  • ~1.5x greater in Medicaid-insured infants

Reference

  1. Kong AM, Krilov LR, Fergie J, et al. Am J Perinatol. 2018; 35(02): 192-200.

RSV=respiratory syncytial virus; wGA=weeks gestational age; CLDP=chronic lung disease of prematurity; CHD=congenital heart disease; CI=confidence interval; CA=chronological age.