Clinical and epidemiological impact of respiratory syncytial virus and identification of risk factors for severe disease in children hospitalized due to acute respiratory tract infection

Introduction: Severe acute respiratory tract infection (ARTI) is a very common cause of hospitalization in pediatrics; respiratory syncytial virus (RSV) is the major etiologic agent. Accurately defining the burden of RSV life-threatening disease (LTD) and its risk factors is a challenge. Objectives: To know the impact of RSV in children hospitalized due to ARTI and describe the risk factors for LTD. Materials and methods: Prospective study in children < 2 years old hospitalized due to ARTI during 2012-2013 at Hospital de Ninos "R. Gutierrez." LTD was defined as requiring non-invasive ventilation and/or mechanical ventilation. Results: 622 studied children, 372 were RSV(+) (59.8 %). Annual rate of hospitalization due to RSV in infants < 1 year old: 956 (95 % CI: 858-1062)/10 000 hospitalizations. RSV caused 56/78 (71.8 %) cases of LTD; 42 (75 %) were previously healthy subjects; 32 (76.2 %) were < 6 months old. In the multivariate analysis, RSV was a risk factor for LTD (adjusted odds ratio [aOR]: 2.04; 95 % CI: 1.15-3.63; p = 0.014). A differential effect by sex was identified in RSV(+) patients: over-crowding was a risk factor for LTD in males (aOR: 2.36; 95 % CI: 1.07-5.21; p = 0.033); breastfeeding was a significant protective factor in females (aOR: 0.342; 95 % CI: 0.13-0.91; p = 0.032). Conclusions: RSV caused more than half of ARTI cases and mostly affected previously healthy patients < 1 year old. Males living in overcrowding conditions and females who were not breastfed were at the greatest risk for LTD.