Instruments to assess secondhand smoke exposure in large cohorts of never smokers: The smoke scales

© 2014 The Authors. Published by PLOS. This is an open access article available under a Creative Commons licence. The published version can be accessed at the following link on the publisher’s website: https://doi.org/10.1371/journal.pone.0085809The objectives of this study were to: (i) to develop questionnaires that can identify never-smoking children and adults experiencing increased exposure to secondhand smoke (SHS+), (ii) to determine their validity against hair nicotine, and (iii) assess their reliability. A sample of 191 children (85 males; 106 females; 7-18 years) and 95 adult (23 males; 72 females; 18- 62 years) never-smokers consented to hair nicotine analysis and answered a large number of questions assessing all sources of SHS. A randomly-selected 30% answered the questions again after 20-30 days. Prevalence of SHS+ in children and adults was 0.52±0.07 and 0.67±0.10, respectively (p16.5 and >16, respectively. Significant Kappa agreement (p0.05). Area under the curve and McNemar's Chi-square showed no pair-wise differences in sensitivity and specificity at the cutoff point between the two different days for SS-C and SS-A (p>0.05). We conclude that the SS-C and the SS-A represent valid, reliable, practical, and inexpensive instruments to identify children and adult never-smokers exposed to increased SHS. Future research should aim to further increase the validity of the two questionnaires. © 2014 Misailidi et al.Published versio

Results (median ± interquartile range) for hair nicotine and prevalence rates (±95% confidence interval) for SHS+ and SHS- in children and adult never-smokers.

<p>Note: * = χ² significant difference (p<0.05) between SHS+ and SHS–.</p><p> = χ² significant difference (p<0.05) between children and adults.</p><p>Key: SHS+ = positive diagnosis of SHS exposure using the forms; SHS– = negative diagnosis of SHS exposure using the forms.</p

Reliability results for SS-C and SS-A.

<p>Note: * = AUC test statistically significant (p<0.05) from 0.5 (i.e., no diagnostic ability).</p><p>Key: IR = interquartile range; 95%LoA = 95% limits of agreement; %CV = percent coefficient of variation; SE = sensitivity; SP = specificity; PPV = positive predicted value; NPV = negative predicted value; LR = likelihood ratio; AUC = area under the ROC curve; CI95% = 95% confidence interval; SE = standard error.</p

Receiver operating characteristics (ROC) curves for SS-C (A) and SS-A (B) indicating the designated cut off points at 16.5 and 16, respectively.

<p>The points at the ROC curve at the designated cut offs for SS-C (C) and SS-A (D) forms 1 and 2 are also illustrated.</p

Factor loadings for the Smoke Scale in children and adults.

<p>Note: VAS = 10 cm visual analogue scale; Likert = 5-level likert scale (not at all, somewhat, moderately, a lot, extremely).</p