Prevalence and Quantification of Secondhand Smoke Exposure Among Hospitalized Children <6 Years of Age

Using caregiver report and urinary cotinine measures, we defined the prevalence of secondhand smoke (SHS) exposure among young, hospitalized children and compared exposure among those hospitalized with pneumonia versus those with acute, nonrespiratory illnesses.

Children aged <6 years hospitalized with pneumonia or acute, nonrespiratory illnesses were enrolled on admission, and urinary cotinine, a nicotine biomarker, was measured. Caregivers were also queried on home SHS exposure. We modeled associations between sociodemographic characteristics and exposure intensity on the basis of cotinine level (none, light, and heavy) using multivariable proportional odds regression. We also examined associations between SHS exposure intensity and diagnosis (pneumonia versus nonrespiratory illness). For this analysis, diagnosis was the outcome of interest, and urinary cotinine was the primary exposure variable.

Overall, 36% of the 239 enrolled children had reported home SHS exposure, although 77% had detectable levels of urinary cotinine, including 59% with heavy exposure. The highest urinary cotinine level was among children exposed to indoor smoking (7.78 ng/mL, interquartile range 2.93-18.65; P < .001). Increased SHS exposure was associated with non-Hispanic ethnicity, lower household educational attainment, and public insurance. There were no differences in SHS exposure by diagnosis.

Among hospitalized young children, reported home SHS exposure was common but substantially underestimated when compared with urinary cotinine levels. The highest urinary cotinine levels were among children exposed to indoor smoking. Future public health interventions, as well as more robust SHS exposure screenings on hospital admission, are needed to reduce the prevalence of SHS exposure among young children.