Secondhand tobacco smoke exposure among children under 5 years old: questionnaires versus cotinine biomarkers: a cohort study

Abstract

ObjectivesCotinine is the gold standard to estimate prevalence of secondhand tobacco smoke (SHS) exposure, and assay limit of detection (LOD) cut-points are typically used regardless of age. Our aim was to compare the concordance between mother-reported SHS exposure and serum cotinine categorising children as exposed with the assay LOD or age-specific cut-points.DesignData from the Health Outcomes and Measures of the Environment (HOME) Study, a prospective pregnancy and birth cohort.SettingHospital or participants’ homes.Participants389 pregnant women aged 18 years and older, between 13 and 19 weeks of gestation, living in a five-county region of the Cincinnati, Ohio metropolitan area, and with follow-up on their children at birth and ages 12, 24, 36 and 48 months.Primary and secondary outcome measuresChildren’s serum cotinine, mother-reported active smoking and SHS exposure were available at birth and during follow-up visits. We used Cohen’s kappa index to assess concordance between maternal self-report and child’s serum cotinine concentrations. We estimated optimal age-specific cut-points, their sensitivity–specificity and positive–negative predictive values with receiver operating characteristic curves.ResultsSelf-reported exposure and cotinine data were available for 280 women who gave birth to singleton child. When applying the assay LOD (0.015 ng/mL), concordance between maternal report and serum cotinine, without accounting for age, was below 0.23 at all times. When using age-specific cut-points (12 months: 0.11 ng/mL; 24 months: 0.08 ng/mL; 36 months: 0.05 ng/mL and 48 months: 0.04 ng/mL), concordance improved, being low at 12 months (0.39), moderate at 24 and 36 months (0.47 and 0.43) and high at 48 months (0.62).ConclusionsConcordance between mother-reported SHS exposure among children under 5 years and serum cotinine improved considerably after applying the cohort-specific and age-specific cut-points. Future studies are necessary to verify these results.

Concordance assessment through comparison with urine cotinine: Does self-report adequately reflect passive smoking?

“…A low HPS assessed by the self-report does not necessarily mean less exposure to smoking in the home. Previous studies have revealed that SR does not reflect exposure at home fully 17,32 . Thirdhand smoke could happen in home without secondhand smoke, and homes are more vulnerable to long-term exposure to smoking materials, including thirdhand smoke, because people stay more at home than anywhere else 33 .…”

Serum cotinine cut-points for secondhand smoke exposure assessment in children under 5 years: A systemic review

“…One study considered the possibility of misclassification due to the inadequacy of the cut-point [ 40 ]. A recent cohort study assessing SHS exposure among children younger than 5 years, observed that, compared to the assay LOD derived cut-point of 0.015 ng/ml, when using new age-specific cut-points, all of them higher than the mentioned assay threshold, concordance between maternal self-report and serum cotinine improved; actually, the percentage of children reclassified as SHS exposed with cotinine disminished in approximately fifty percentage points when using the age-specific cut-points obtained with ROC curves [ 74 ].…”

Pre‐ and postnatal exposure to secondhand tobacco smoke and body composition at 12 years: periods of susceptibility

“…Cotinine, the major metabolite of nicotine, is one of the most commonly used biomarkers for assessing recent SHS exposure because of its high specificity and sensitivity [4]. In the past decade, more than 40% of US children aged 3 to 11 years had serum cotinine levels consistent with exposure to SHS [5]; we previously showed a similar SHS exposure prevalence among children aged 1 to 4 years from the Health Outcomes and Measures of the Environment (HOME) Study cohort [6].…”