Estimating Respiratory Syncytial Virus-associated Hospitalization in the First Year of Life Among Infants Born at 32–35 Weeks of Gestation

Venessa M. J. Ryan, MSc; Joanne M. Langley, MSc, MD; Linda Dodds, MSc, PhD; Pantelis Andreou, MSc, PhD


Pediatr Infect Dis J. 2016;35(8):851-855. 

In This Article

Abstract and Introduction


Background: Prophylaxis against respiratory syncytial virus-associated hospitalization (RSV-H) with anti-RSV monoclonal antibody is not considered cost-effective for routine use in most jurisdictions. The aim of this study was to develop a scoring tool to estimate local risk of RSV-H in the first year of life among moderately premature infants to assist in prophylaxis decision making.

Methods: A retrospective cohort was constructed from population-based databases in Nova Scotia, Canada, to follow 32- to 35-week gestation infants from the prenatal period to <12 months of age, from 1998 to 2008. Potential risk factors were entered into the logistic regression model, where the dependent variable was RSV-H. Receiver operator characteristic analysis demonstrated cutoff scores producing the highest predictive accuracy, and the likelihood ratio test was used to select the final set of variables for the predictive tool.

Results: In 2811 eligible infants, the overall RSV-H rate was 3.1% (88/2811). Of 17 variables considered, 3 were used to create the scoring tool: birth during December to February, household smoke exposure and household crowding. The positive likelihood ratios of predictive tool scores for high, moderate and low of RSV-H were 3.57, 3.38 and 1.95, whereas posttest probabilities (risk of RSV-H) were 11.4%, 10.8% and 1.6%, respectively.

Conclusions: While able to predict infants at low risk of RSV-H, the tool did not discriminate high from moderate risk infants. The tool could be used in anticipatory care to help educate families about reducing risk of serious RSV illness in their newborn.


Respiratory syncytial virus (RSV) is the leading cause of bronchiolitis and pneumonia in infants and young children;[1,2] worldwide, up to 199,000 deaths and 33 million episodes occur each year.[3] There are no vaccines available and treatment is symptomatic. In 2 randomized controlled clinical trials, the RSV-specific monoclonal antibody palivizumab reduced the risk of RSV-associated hospitalization (RSV-H) in premature infants and those with certain cardiac and lung disorders.[4] In most jurisdictions, this passive prophylaxis is not considered cost-effective for routine use and is recommended only for those considered at highest risk of severe RSV-associated illness, such as those born at ≤29 weeks of gestation.[5–7] Given the high cost of prophylaxis, several research groups have studied local RSV epidemiology and developed predictive indices to identify a subset of moderately premature children who could be offered palivizumab.[8–13]

The purpose of this study was to determine if a subset of infants 32- to 35-weeks gestational age (wGA) could be identified, based on risk factors present at the time of birth, to be at higher risk of RSV-H. Access to a maternal–perinatal population-based database used comprehensively throughout our province, and a universal healthcare system capturing all hospital admissions allowed creation of a retrospective cohort of children that was followed from the perinatal period through the first year of life for RSV-H.