Respiratory Syncytial Virus Preterm (32-36 Completed Weeks of Gestation) Risk Estimation Measure for RSV Hospitalization in Ireland: A Prospective Study

Abstract

Background: In several countries, respiratory syncytial virus prophylaxis is offered to late preterm infants who are at escalated risk of respiratory syncytial virus hospitalization (RSVH). However, targeted prophylaxis should be informed by country-specific data. This study, which uniquely includes 36 weeks of gestational age (GA) infants, aims to establish the risk factors for RSVH in 32-36 weeks of GA infants in Ireland.

Methods: A prospective observational study at 13 hospitals of laboratory-confirmed RSVH in nonprophylaxed 32-36 weeks of GA infants was conducted from July 2011 to February 2014. Baseline and first-year clinical data were analyzed by using SPSS software Version 22 (IBM Corp, Armonk, NY). Significant (P < 0.05) variables were entered into multiple logistic regression to determine the independent risk factors for RSVH.

Results: Sixty-three percent of eligible infants (1825 of 2877) were recruited. The RSVH rate was 3.6% (65 of 1807 analyzed infant records). There was no RSV-attributable mortality. Twelve infants required intensive care. Of the 15 variables correlating to RSVH, 5 independent risk factors were identified: older siblings [odds ratio (OR): 3.8; 95% confidence interval (CI): 1.97-7.41], being Caucasian (OR: 2.3; 95% CI: 1.04-5.29), neonatal respiratory morbidity (OR: 2.2; 95% CI: 1.28-3.94); birth July 15 to December 15 (OR: 2.1; 95% CI: 1.09-3.92) and family history of asthma (OR: 1.9; 95% CI: 1.01-3.39). Birth from 36 weeks to 36 + 6 days mitigated RSVH risk (relative risk: 0.58; 95% CI: 0.34-0.99); however, risk factors were similar to the 32-35 weeks of GA cohort.

Conclusion: Neonatal respiratory morbidity or being Caucasian were the population-specific independent risk factors for RSVH in 32-36 weeks of GA in Ireland, whereas the other identified independent risk factors mirrored those established in previous studies.