Severity of respiratory syncytial virus bronchiolitis is increased in children with passive smoking exposure

Abstract

Background: Respiratory syncytial virus (RSV) bronchiolitis is one of the most common causes for hospitalization in the first year of life. Second-hand cigarette smoke (SHS) has been shown to increase the severity of respiratory illnesses and as a major metabolite of Nicotine, urinary Cotinine has been shown to be a reliable marker for SHS exposure. Aim of this study was to compare severity of RSV bronchiolitis in children with and without increased urinary Cotinine levels. Methods: A prospective study was performed including children aged below 12 months hospitalized with RSV bronchiolitis in Wilhelminen-Hospital Vienna. RSV infection was confirmed with nasopharyngeal swab and RSV enzyme-immuno-assay and urinary Cotinine levels (measured by chromatography tandem mass spectography) were assessed as indicator for SHS. Main outcome, assessing clinical severity, was oxygen (O2)-saturation (%) at rest on admission. Secondary outcomes were “Clinical severity score at admission” (CSSA) and “Disease severity score“ (DSS) combining different respiratory parameters. Results: Eighty-one patients with a mean age of 106 days (SD: ± 80) were included. Results of 13 (16%) patients with SHS (urinary cotinine ≥ 7ng/dl) and 68 (84%) without SHS exposure were analyzed. Mean O2-saturation for patients with and without SHS exposure was 95.1 % and 96,6 %, respectively (p U-test =0.045). Mean CSSA and DSS for patients with and without SHS exposure was 3.1 versus 2.5,(p=0.014) and 1.6 versus 2.4 (n.s.). Conclusions: The data show, that children hospitalized for RSV bronchiolitis with SHS exposure have significantly lower 02-saturation and a worse CSSA than children without SHS exposure.