Impact of expanding smoke-free policies beyond enclosed public places and workplaces on children’s tobacco smoke exposure and respiratory health: protocol for a systematic review and meta-analysis

Abstract

IntroductionTobacco smoke exposure (TSE) has considerable adverse respiratory health impact among children. Smoke-free policies covering enclosed public places are known to reduce child TSE and benefit child health. An increasing number of jurisdictions are now expanding smoke-free policies to also cover outdoor areas and/or (semi)private spaces (indoor and/or outdoor). We aim to systematically review the evidence on the impact of these ‘novel smoke-free policies’ on children’s TSE and respiratory health.Methods and analysis13 electronic databases will be searched by two independent reviewers for eligible studies. We will consult experts from the field and hand-search references and citations to identify additional published and unpublished studies. Study designs recommended by the Cochrane Effective Practice and Organisation of Care (EPOC) group are eligible, without restrictions on the observational period, publication date or language. Our primary outcomes are: self-reported or parental-reported TSE in places covered by the policy; unplanned hospital attendance for wheezing/asthma and unplanned hospital attendance for respiratory infections. We will assess risk of bias of individual studies following the EPOC or Risk Of Bias In Non-randomised Studies of Interventions tool, as appropriate. We will conduct separate random effects meta-analyses for smoke-free policies covering (1) indoor private places, (2) indoor semiprivate places, (3) outdoor (semi)private places and (4) outdoor public places. We will assess whether the policies were associated with changes in TSE in other locations (eg, displacement). Subgroup analyses will be conducted based on country income classification (ie, high, middle or low income) and by socioeconomic status. Sensitivity analyses will be undertaken via broadening our study design eligibility criteria (ie, including non-EPOC designs) or via excluding studies with a high risk of bias. This review will inform policymakers regarding the implementation of extended smoke-free policies to safeguard children’s health.Ethics and disseminationEthical approval is not required. Findings will be disseminated to academics and the general public.PROSPERO registration numberCRD42020190563.

Effect of smoke-free policies in outdoor areas and private places on children's tobacco smoke exposure and respiratory health: a systematic review and meta-analysis

“…We did a sensitivity analysis including studies with a less robust design. 16,19 A priori, we planned a number of other sensitivity and subgroup analyses that we could not complete due to the low number of eligible studies. 16 We present findings on effect modification by socioeconomic status, when it was reported.…”

“…16,19 A priori, we planned a number of other sensitivity and subgroup analyses that we could not complete due to the low number of eligible studies. 16 We present findings on effect modification by socioeconomic status, when it was reported. In addition to quantitative study findings, we narratively describe additional elements from individual studies that might support causal inference.…”

“…This systematic review and meta-analysis was done in accordance with our peer-reviewed, published protocol, 16…”

“…6 Smoke-free policies have been identified as a key component in achieving the UN Sustainable Development Goal 3 to improve child health and wellbeing. 7,8 Solid evidence indicates that smoke-free policies covering enclosed public places can effectively reduce adverse respiratory health outcomes in children, including decreases in hospital attendance for asthma exacerbations by 10% (95% CI [3][4][5][6][7][8][9][10][11][12][13][14][15][16][17] and for lower respiratory tract infections by 18% (4-33). 5 These health benefits are likely to be mediated via a reduction in TSE from second-hand and possibly third-hand smoke.…”

European progress in working towards a tobacco-free generation

“…As children do not have substantial control over their environment, and as smoking inside vehicles is linked to very high levels of toxins, these measures are justified to reduce exposure and harm. Emerging evidence now indicates that these laws can help reduce exposure to SHS among children in vehicles [42].…”