Increased severity of respiratory syncytial virus airway infection due to passive smoke exposure.

OBJECTIVE

Aim of this study was to analyze whether children with objectively measured second-hand cigarette smoke (SHS) exposure suffer from a more severe course of disease when hospitalized with lower respiratory tract infection (LRTI) due to respiratory syncytial virus (RSV).

METHODS

This prospective study was conducted at the Department of Pediatrics, Wilhelminen-Hospital, Vienna, Austria in children aged below 1 year without a history of preceding lung disease and with acute symptoms of LRTI and a positive nasopharyngeal swab for RSV. On admission, urinary cotinine was measured as a marker of recent SHS and clinical severity of LRTI was assessed by oxygen saturation SpO2 and the "admission clinical severity score" (CSSA). Parents/caregivers were asked to complete a customized questionnaire assessing risks for SHS and demographic characteristics.

RESULTS

After inclusion of 217 patients, data of 185 patients with a mean (SD) age of 106 days (80) were analyzed. Twenty-five patients (13.5%) were "cotinine-positive" (COT+) defined as a urinary cotinine level of ≥7 μg/L. SpO2 on admission was significantly lower in children recently exposed to SHS defined objectively by COT+ (94.8%  ±2.0) in urine on admission compared to children not recently exposed (COT-) (96.8% ±3.0; P < 0.01). Disease severity, assessed via mean clinical severity score on admission (CSSA) for COT+ and COT- was 2.56 and 1.71, respectively (P = 0.03).

CONCLUSIONS

Recent exposure to SHS was associated with lower O2 saturation and higher clinical severity score, measured by urine cotinine levels in children hospitalized for RSV infection under 1 year of age.