Reduction in emergency department visits for children's asthma, ear infections, and respiratory infections after the introduction of state smoke-free legislation

Tobacco Exposure During Pregnancy and Infections in Infants up to 1 Year of Age: The Japan Environment and Children's Study

BACKGROUND

Tobacco exposure during pregnancy is associated with several adverse outcomes in infants. We investigated the association between tobacco exposure during pregnancy (both active and second-hand) and various infections in infants up to 1 year.

METHODS

This prospective cohort study used a fixed dataset (jecs-an-20180131) from the Japan Environment and Children's Study of registered births in Japan during 2011-2014 that included 104,065 fetal records from enrolled pregnant women. Based on the participants' responses to the questionnaire on smoking status, mothers were first divided into "never smoked," "quit smoking," and "current smoker" groups and then into "no second-hand smoking (SHS)" and "SHS" groups. Infectious diseases included central nervous system infection, otitis media (OM), upper respiratory tract infection (URTI), lower respiratory tract infection (LRTI), gastroenteritis (GI), and urinary tract infection. Adjusted odds ratios (aORs) and 95% confidence intervals (CIs) were calculated using logistic regression analysis and adjusted for maternal, socioeconomic, and postnatal confounding factors.

RESULTS

Among the 73,205 newborns enrolled, multivariable analysis revealed that the aOR of LRTI and GI was 1.20 (95% CI, 1.07-1.33) and 1.18 (95% CI, 1.04-1.35), respectively, for the "current smoker with/without SHS" group compared with the "never smoked without SHS" group. "Quit smoking without SHS" was not associated with the risk of LRTI. SHS was associated with an increased risk of OM, URTI, LRTI, and GI, especially with LRTI and GI.

CONCLUSION

Exposure to tobacco smoke during pregnancy was associated with an increased risk of OM, URTI, LRTI, and GI in infants during their first year of life.

Evaluation of Population-Level Tobacco Control Interventions and Health Outcomes: A Systematic Review and Meta-Analysis

Importance

Smoking causes considerable noncommunicable diseases, perinatal morbidity, and mortality.

Objective

To investigate the associations of population-level tobacco-control policies with health outcomes.

Data Sources

PubMed, EMBASE, Web of Science, Cumulated Index to Nursing and Allied Health Literature, and EconLit were searched from inception to March 2021 (updated on 1 March 2022). References were manually searched.

Study Selection

Studies reporting on associations of population-level tobacco control policies with health-related outcomes were included. Data were analyzed from May to July 2022.

Data Extraction and Synthesis

Data were extracted by 1 investigator and cross-checked by a second investigator. Analyses were conducted using the Preferred Reporting Items for Systematic Reviews and Meta-analyses reporting guideline.

Main Outcomes and Measures

The primary outcomes were respiratory system disease (RSD), cardiovascular disease (CVD), cancer, mortality, hospitalization, and health care utilization. The secondary outcomes were adverse birth outcomes, such as low birth weight and preterm birth. Random-effects meta-analysis was used to estimate pooled odds ratios (ORs) and 95% CIs.

Results

Of 4952 records identified, 144 population-level studies were included in the final analysis; 126 studies (87.5%) were of high or moderate quality. The most frequently reported policies were smoke-free legislation (126 studies), followed by tax or price increases (14 studies), multicomponent tobacco control programs (12 studies), and a minimum cigarette purchase age law (1 study). Smoke-free legislation was associated with decreased risk of all CVD events (OR, 0.90; 95% CI, 0.86-0.94), RSD events (OR, 0.83; 95% CI, 0.72-0.96), hospitalization due to CVD or RSD (OR, 0.91; 95% CI, 0.87-0.95), and adverse birth outcomes (OR, 0.94; 95% CI, 0.92-0.96). These associations persisted in all sensitivity and subgroup analyses, except for the country income category, for which a significant reduction was only observed in high-income countries. In meta-analysis, there was no clear association of tax or price increases with adverse health outcomes. However, for the narrative synthesis, all 8 studies reported statistically significant associations between tax increases and decreases in adverse health events.

Conclusions and Relevance

In this systematic review and meta-analysis, smoke-free legislation was associated with significant reductions in morbidity and mortality related to CVD, RSD, and perinatal outcomes. These findings support the need to accelerate the implementation of smoke-free laws to protect populations against smoking-related harm.

Particle Exposure Hazards of Visiting Outdoor Smoking Areas for Patients with Asthma or COPD Even in EU Countries with Comprehensive Smokefree Laws

Smokefree laws are intended to protect against second-hand smoke (SHS) in outdoor areas. We examined if exposure to PM2.5 particles in outdoor smoking areas changed breathing rates in 60 patients with asthma (n = 30) or with COPD (n = 30), in an open, non-randomised, interventional study model in Czechia, Ireland and Spain. The patients wore a PM2.5 particle monitor (AirSpeck) and a breath monitor (RESpeck) for 24 h to determine changes in breathing rates (Br) at rest and during a visit to an outside smoking area. Spirometry and breath CO were measured before and the day after visiting an outdoor smoking area. The PM2.5 levels at the 60 venues were highly variable, ranging from ≥2000 µg/m3 (in 4 premises) to ≤10 µg/m3 (in 3 premises, which had only a single wall in the structure). At 39 venues, the mean PM 2.5 levels were ≥25 µg/m3. The breathing rate changed significantly in 57 of the 60 patients, resulting in an increase in some patients and a decrease in others. Comprehensive smokefree laws were ineffective in protecting asthma and COPD patients from exposure to high levels of SHS in outside areas of pubs and terraces, which should be avoided by these patients. These findings also support the extension of smokefree laws to outside areas.

Global, regional, and national deaths, disability-adjusted life years, years lived with disability, and years of life lost for the global disease burden attributable to second-hand smoke, 1990-2019: A systematic analysis for the Global Burden of Disease Study

BACKGROUND

Smoke-free policies have led to a decline in smoking prevalence. Nevertheless, as the global population grows, more non-smokers are exposed to second-hand smoke (SHS) hazards. Mitigating SHS hazards requires a systematic analysis of the global disease burden attributable to SHS.

METHODS

Data on SHS was extracted from the Global Burden of Disease Study 2019. First, we measured the disease burden of SHS by the number of cases and age-standardized rates of deaths, disability-adjusted life years (DALYs), years lived with disability (YLDs), and years of life lost (YLLs) from 1990 to 2019. Second, trends in the disease burden of SHS in different periods were estimated based on the annual percentage change (APC) by joinpoint regression analysis. Finally, using histogram plots, world maps, Pearson correlation analysis, and population attributable fraction (PAF), we conducted a stratified analysis of SHS exposure by sex, age, geographic location, sociodemographic index (SDI) level, and disease.

RESULTS

The number of deaths caused by SHS remained stable between 1990 and 2019, and the number of YLDs more than doubled in three decades. In contrast, the number of DALYs and YLLs caused by SHS decreased. The declining trend in deaths (APC = -1.42 % [95 % UI -1.79 %, -1.05 %]), DALYs (APC = -1.91 % [95 % UI -2.15 %, -1.67 %]), and YLLs (APC = -1.28 % [95 % UI -1.93 %, -0.64 %]) had slowed down in recent years, while SHS-related YLDs were still increasing (APC = 1.84 % [95 % UI 0.74 %, 2.96 %]). From 2010 to 2019, we found that SHS exposure increased the risk of tracheal, bronchus, and lung cancer (PAF increased by 11.75 %), breast cancer (PAF increased by 5.36 %), diabetes mellitus (PAF increased by 8.24 %), and ischemic heart disease (PAF increased by 4.46 %). In addition, the disease burden caused by SHS was highest in middle SDI and low-middle SDI countries.

CONCLUSION

The global disease burden attributable to SHS is still severe, and policymakers need to implement more effective measures to reduce the harm of SHS.

Effect of smoke-free legislation on respiratory health services use in children with asthma: a population-based open cohort study in Ontario, Canada

OBJECTIVE

This study will add to existing literature by examining the impact of smoke-free legislation in outdoor areas among children with asthma. We aimed to examine the effect of the 2015 Smoke-Free Ontario Act (SFOA) amendment, which prohibited smoking on patios, playgrounds and sports fields, on health services use (HSU) rates in children with asthma.

METHODS

We conducted a population-based open cohort study using health administrative data from the province of Ontario, Canada. Each year, all Ontario residents aged 0-18 years with physician diagnosed asthma were included in the study. Annual rates of HSU (emergency department (ED) visits, hospitalisations and physician office visits) for asthma and asthma-related conditions (eg, bronchitis, allergic rhinitis, influenza and pneumonia) were calculated. Interrupted time-series analysis, accounting for seasonality, was used to estimate changes in HSU following the 2015 SFOA.

RESULTS

The study population ranged from 618 957 individuals in 2010 to 498 812 in 2018. An estimated average increase in ED visits for asthma in infants aged 0-1 years of 0.42 per 100 individuals (95% CI: 0.09 to 0.75) and a 57% relative increase corresponding to the 2015 SFOA was observed. A significant decrease in ED visits for asthma-related conditions of 0.19 per 100 individuals (95% CI: -0.37 to -0.01) and a 22% relative decrease corresponding to the 2015 SFOA was observed.

CONCLUSION

Based on the observed positive effect of restricting smoking on patios, playgrounds and sports fields on respiratory morbidity in children with asthma, other jurisdictions globally should consider implementing similar smoke-free policies.

Associations between smoke-free vehicle legislation and childhood admissions to hospital for asthma in Scotland: an interrupted time-series analysis of whole-population data

BACKGROUND

In Scotland, childhood admissions to hospital for asthma fell from March, 2006, after legislation was introduced to prohibit smoking in public places. In December, 2016, new Scottish legislation banned smoking in vehicles containing a child. We aimed to determine whether the introduction of this new legislation produced additional benefits.

METHODS

We obtained data on all asthma emergency admissions to hospitals in Scotland between 2000 and 2018 for individuals younger than 16 years. We used interrupted time-series analyses to study changes in monthly incidence of asthma emergency admissions to hospital per 100 000 children after the introduction of smoke-free vehicle legislation, taking into account previous smoke-free interventions. We did subgroup analyses according to age and area deprivation, using the Scottish Index of Multiple Deprivation, and repeated the analyses for a control condition, gastroenteritis, and other respiratory conditions.

FINDINGS

Of the 32 342 emergency admissions to hospital for asthma among children younger than 16 years over the 19-year study period (Jan 1, 2000, to Dec 31, 2018), 13 954 (43%) were among children younger than 5 years and 18 388 (57%) were among children aged 5-15 years. After the introduction of smoke-free vehicle legislation, there was a non-significant decline in the slope for monthly emergency admissions to hospital for asthma among children younger than 16 years (-1·21%, 95% CI -2·64 to 0·23) relative to the underlying trend in hospital admissions for childhood asthma. However, children younger than 5 years had a significant decline in the slope for monthly asthma admissions (-1·49%, -2·69 to -0·27) over and above the underlying trend among children in this age group (equivalent to six fewer hospitalisations per year), but no such decline was seen in children aged 5-15 years. Monthly admissions to hospital for asthma fell significantly among children living in the most affluent areas (-2·27%, -4·41 to -0·07) but not among those living in the most deprived areas. We found no change in admissions to hospital for gastroenteritis or other respiratory conditions after the introduction of the smoke-free vehicle legislation.

INTERPRETATION

Although legislation banning smoking in vehicles did not affect hospital admissions for severe asthma among children overall or in the older age group, this legislation was associated with a reduction in severe asthma exacerbations requiring hospital admission among preschool children, over and above the underlying trend and previous interventions designed to reduce exposure to second-hand smoke. Similar legislation prohibiting smoking in vehicles that contain children should be adopted in other countries.

FUNDING

None.

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

BACKGROUND

Smoke-free policies in outdoor areas and semi-private and private places (eg, cars) might reduce the health harms caused by tobacco smoke exposure (TSE). We aimed to investigate the effect of smoke-free policies covering outdoor areas or semi-private and private places on TSE and respiratory health in children, to inform policy.

METHODS

In this systematic review and meta-analysis, we searched 13 electronic databases from date of inception to Jan 29, 2021, for published studies that assessed the effects of smoke-free policies in outdoor areas or semi-private or private places on TSE, respiratory health outcomes, or both, in children. Non-randomised and randomised trials, interrupted time series, and controlled before-after studies, without restrictions to the observational period, publication date, or language, were eligible for the main analysis. Two reviewers independently extracted data, including adjusted test statistics from each study using a prespecified form, and assessed risk of bias for effect estimates from each study using the Risk of Bias in Non-Randomised Studies of Interventions tool. Primary outcomes were TSE in places covered by the policy, unplanned hospital attendance for wheezing or asthma, and unplanned hospital attendance for respiratory tract infections, in children younger than 17 years. Random-effects meta-analyses were done when at least two studies evaluated policies that regulated smoking in similar places and reported on the same outcome. This study is registered with PROSPERO, CRD42020190563.

FINDINGS

We identified 5745 records and assessed 204 full-text articles for eligibility, of which 11 studies met the inclusion criteria and were included in the qualitative synthesis. Of these studies, seven fit prespecified robustness criteria as recommended by the Cochrane Effective Practice and Organization of Care group, assessing smoke-free cars (n=5), schools (n=1), and a comprehensive policy covering multiple areas (n=1). Risk of bias was low in three studies, moderate in three, and critical in one. In the meta-analysis of ten effect estimates from four studies, smoke-free car policies were associated with an immediate TSE reduction in cars (risk ratio 0·69, 95% CI 0·55-0·87; 161 466 participants); heterogeneity was substantial (I² 80·7%; p<0·0001). One additional study reported a gradual TSE decrease in cars annually. Individual studies found TSE reductions on school grounds, following a smoke-free school policy, and in hospital attendances for respiratory tract infection, following a comprehensive smoke-free policy.

INTERPRETATION

Smoke-free car policies are associated with reductions in reported child TSE in cars, which could translate into respiratory health benefits. Few additional studies assessed the effect of policies regulating smoking in outdoor areas and semi-private and private places on children's TSE or health outcomes. On the basis of these findings, governments should consider including private cars in comprehensive smoke-free policies to protect child health.

FUNDING

Dutch Heart Foundation, Lung Foundation Netherlands, Dutch Cancer Society, Dutch Diabetes Research Foundation, Netherlands Thrombosis Foundation, and Health Data Research UK.

Associations between a smoke-free homes intervention and childhood admissions to hospital in Scotland: an interrupted time-series analysis of whole-population data

BACKGROUND

Many children are exposed to second-hand smoke in the home and are at increased risk of asthma and other respiratory conditions. In Scotland, a public health mass-media campaign was launched on March 24, 2014, called Take it Right Outside (TiRO), with a focus on reducing the exposure of children to domestic second-hand smoke. In this study, our aim was to establish whether the TiRO campaign was followed by a decrease in hospital admissions for childhood asthma and other respiratory conditions related to second-hand smoke exposure across Scotland.

METHODS

For an interrupted time-series analysis, data were obtained on all hospital admissions in Scotland between 2000 and 2018 for children aged younger than 16 years. We studied changes in the monthly incidence of admissions for conditions potentially related to second-hand smoke exposure (asthma, lower respiratory tract infection, bronchiolitis, croup, and acute otitis media) per 1000 children following the 2014 TiRO campaign, while considering national legislation banning smoking in public spaces from 2006. We considered asthma to be the primary condition related to second-hand smoke exposure, with monthly asthma admissions as the primary outcome. Gastroenteritis was included as a control condition. The analysis of asthma admissions considered subgroups stratified by age and area quintile of the Scottish Index of Multiple Deprivations (SIMD).

FINDINGS

740 055 hospital admissions were recorded for children. 138 931 (18·8%) admissions were for respiratory conditions potentially related to second-hand smoke exposure, of which 32 342 (23·3%) were for asthma. After TiRO in 2014, we identified a decrease relative to the underlying trend in the slope of admissions for asthma (-0·48% [-0·85 to -0·12], p=0·0096) in younger children (age <5 years), but not in older children (age 5-15 years). Asthma admissions did not change after TiRO among children 0-15 years of age when data were analysed according to area deprivation quintile. Following the 2006 legislation, independent of TiRO, asthma admissions decreased in both younger children (-0·36% [-0·67 to -0·05], p=0·021) and older children (-0·68% [-1·00 to -0·36], p<0·0001), and in children from the most deprived (SIMD 1; -0·49% [-0·87 to -0·11], p=0·011) and intermediate deprived (SIMD 3; -0·70% [-1·17 to -0·23], p=0·0043) area quintiles, but not in those from the least deprived (SIMD 5) area quintile.

INTERPRETATION

Our findings suggest that smoke-free home interventions could be an important tool to reduce asthma admissions in young children, and that smoke-free public space legislation might improve child health for many years, especially in the most deprived communities.

FUNDING

University of Aberdeen Research Excellence Framework 2021 Impact Support Award Scheme.

Impact of Air Pollution on Asthma Outcomes

Asthma is a chronic respiratory disease characterized by variable airflow obstruction, bronchial hyperresponsiveness, and airway inflammation. Evidence suggests that air pollution has a negative impact on asthma outcomes in both adult and pediatric populations. The aim of this review is to summarize the current knowledge on the effect of various outdoor and indoor pollutants on asthma outcomes, their burden on its management, as well as to highlight the measures that could result in improved asthma outcomes. Traffic-related air pollution, nitrogen dioxide and second-hand smoking (SHS) exposures represent significant risk factors for asthma development in children. Nevertheless, a causal relation between air pollution and development of adult asthma is not clearly established. Exposure to outdoor pollutants can induce asthma symptoms, exacerbations and decreases in lung function. Active tobacco smoking is associated with poorer asthma control, while exposure to SHS increases the risk of asthma exacerbations, respiratory symptoms and healthcare utilization. Other indoor pollutants such as heating sources and molds can also negatively impact the course of asthma. Global measures, that aim to reduce exposure to air pollutants, are highly needed in order to improve the outcomes and management of adult and pediatric asthma in addition to the existing guidelines.

Immunity-targeted approaches to the management of chronic and recurrent upper respiratory tract disorders in children

Background

Upper respiratory tract infections (URTIs), including rhinitis, nasopharyngitis, tonsillitis and otitis media (OM), comprise of 88% of total respiratory infections, especially in children. Therefore effective prevention and treatment of RTIs remain a high priority worldwide. Preclinical and clinical data highlight the rationale for the use and effectiveness of immunity‐targeted approaches, including targeted immunisations and non‐specific immunomodulation in the prevention and management of recurrent upper RTIs.

Objective of review

The idea of this review was to summarise the current evidence and address key questions concerning the use of conservative and immunity‐targeted approaches to recurrent and chronic URTIs, with a focus on the paediatric population.

Search strategy/Evaluation method

Literature searches were conducted in March 2017 and updated in September 2017 using: Academic Search Complete; CENTRAL; Health Source: Nursing/Academic Edition; MEDLINE; clinicaltrials.gov; and Cochrane databases. In total, 84 articles were retrieved and reviewed. Two independent researchers focused on primary and secondary endpoints in systematic reviews, meta‐analyses and randomised, controlled trials, using immunity‐directed strategies as the control group or within a subpopulation of larger studies. Existing guidelines and interventional/observational studies on novel applications were also included.

Results

Children are particularly susceptible to RTIs due to the relative immaturity of their immune systems, as well as other potential predisposing factors such as day care attendance and/or toxic environmental factors (eg increased pathogenic microbial exposure and air pollutants). Recurrent URTIs can affect otherwise healthy children, leading to clinical sequelae and complications, including the development of chronic conditions or the need for surgery. Available pre‐clinical and clinical data highlight the rationale for the use and effectiveness of immunity‐targeted approaches, including targeted immunisations (flu and pneumococcal vaccines) and non‐specific immunomodulation (bacterial lysates), in the prevention and management of recurrent croup, tonsillitis, otitis media, recurrent acute rhinosinusitis and chronic rhinosinusitis.

Conclusions

In this review, we summarise the current evidence and provide data demonstrating that some immunity‐targeted strategies, including vaccination and immunomodulation, have proved effective in the treatment and prevention of recurrent and chronic URTIs in children.

Assessing the impact of air pollution on childhood asthma morbidity: how, when, and what to do

PURPOSE OF REVIEW

Exposure to air pollutants is linked with poor asthma control in children and represents a potentially modifiable risk factor for impaired lung function, rescue medication use, and increased asthma-related healthcare utilization. Identification of the most relevant pollutants to asthma as well as susceptibility factors and strategies to reduce exposure are needed to improve child health.

RECENT FINDINGS

The current available literature supports the association between pollutants and negative asthma outcomes. Ethnicity, socioeconomic status, and presence of certain gene polymorphisms may impact susceptibility to the negative health effects of air pollution. Improved air quality standards were associated with better asthma outcomes.

SUMMARY

The link between air pollution and pediatric asthma morbidity is supported by the recent relevant literature. Continued efforts are needed to identify the most vulnerable populations and develop strategies to reduce exposures and improve air quality.

Smoke-free legislation and paediatric hospitalisations for acute respiratory tract infections: national quasi-experimental study with unexpected findings and important methodological implications

Objectives

We investigated whether Scottish implementation of smoke-free legislation was associated with a reduction in unplanned hospitalisations or deaths (‘events’) due to respiratory tract infections (RTIs) among children.

Design

Interrupted time series (ITS).

Setting/participants

Children aged 0–12 years living in Scotland during 1996–2012.

Intervention

National comprehensive smoke-free legislation (March 2006).

Main outcome measure

Acute RTI events in the Scottish Morbidity Record-01 and/or National Records of Scotland Death Records.

Results

135 134 RTI events were observed over 155 million patient-months. In our prespecified negative binomial regression model accounting for underlying temporal trends, seasonality, sex, age group, region, urbanisation level, socioeconomic status and seven-valent pneumococcal vaccination status, smoke-free legislation was associated with an immediate rise in RTI events (incidence rate ratio (IRR)=1.24, 95% CI 1.20 to 1.28) and an additional gradual increase (IRR=1.05/year, 95% CI 1.05 to 1.06). Given this unanticipated finding, we conducted a number of post hoc exploratory analyses. Among these, automatic break point detection indicated that the rise in RTI events actually preceded the smoke-free law by 16 months. When accounting for this break point, smoke-free legislation was associated with a gradual decrease in acute RTI events: IRR=0.91/year, 95% CI 0.87 to 0.96.

Conclusions

Our prespecified ITS approach suggested that implementation of smoke-free legislation in Scotland was associated with an increase in paediatric RTI events. We were concerned that this result, which contradicted published evidence, was spurious. The association was indeed reversed when accounting for an unanticipated antecedent break point in the temporal trend, suggesting that the legislation may in fact be protective. ITS analyses should be subjected to comprehensive robustness checks to assess consistency.

Smoke-free homes and attitudes towards banning smoking in vehicles carrying children in Spain (2016)

OBJECTIVE

To describe the voluntary adoption of smoke-free homes and social attitudes in Spain towards banning smoking in vehicles in which children are present.

METHODS

Cross-sectional study of a representative sample of the adult Spanish population age range, 18-75 years (n=1036). The field work was conducted via a computer-assisted telephone survey in March and April 2016. Survey respondents answered questions about smoking rules at home and attitudes towards a smoking ban in cars with or without children. Home smoking rules were defined as complete (smoking not allowed anywhere in the house), partial (smoking allowed in some areas inside the house) or absent (smoking allowed everywhere).

RESULTS

Most (83.0%) of the surveyed population had some type of smoking restriction in place at home (45.6% complete and 37.5% partial). There were significant differences between groups according to age group (the highest prevalence was 86.1% from 66 to 75 years and the lowest prevalence was 77.8% from 46 to 65 years) and smoking status (the highest prevalence was 89.4% in people who had never been smokers and the lowest prevalence was 75.0% in current smokers) with regards to the prevalence of smoke-free homes (p<0.05), with partial bans more prevalent in smoking households (49.0%). Most (61.6%) of the population favored banning smoking in cars, and 90.1% supported a ban in cars carrying minors. Attitudes towards smoking regulation in cars (with or without children) varied significantly by age group (the highest prevalence was 81.9% from 66 to 75 years and the lowest prevalence was 54.5% from 18 to 45 years) and smoking status (the highest prevalence was 71.4% in people who had never been smokers and the lowest prevalence was 46.0% in current smokers). However, no significant differences were found with regard to attitudes towards smoking regulation in cars carrying children, regardless of sex, age, social class, or smoking status.

CONCLUSION

Approximately half of the adult population in Spain have implemented a complete smoke-free rule at home. More than 9 out of 10 adults favor regulating smoking in cars in the presence of minors. These findings support the expansion of smoke-free regulations to include private vehicles, particularly when minors are in the car.

Effect of tobacco control policies on perinatal and child health: a systematic review and meta-analysis

BACKGROUND

Tobacco smoking and smoke exposure during pregnancy and childhood cause considerable childhood morbidity and mortality. We did a systematic review and meta-analysis to investigate whether implementation of WHO's recommended tobacco control policies (MPOWER) was of benefit to perinatal and child health.

METHODS

We searched 19 electronic databases, hand-searched references and citations, and consulted experts to identify studies assessing the association between implementation of MPOWER policies and child health. We did not apply any language restrictions, and searched the full time period available for each database, up to June 22, 2017. Our primary outcomes of interest were perinatal mortality, preterm birth, hospital attendance for asthma exacerbations, and hospital attendance for respiratory tract infections. Where possible and appropriate, we combined data from different studies in random-effects meta-analyses. This study is registered with PROSPERO, number CRD42015023448.

FINDINGS

We identified 41 eligible studies (24 from North America, 16 from Europe, and one from China) that assessed combinations of the following MPOWER policies: smoke-free legislation (n=35), tobacco taxation (n=11), and smoking cessation services (n=3). Risk of bias was low in 23 studies, moderate in 16, and high in two. Implementation of smoke-free legislation was associated with reductions in rates of preterm birth (-3·77% [95% CI -6·37 to -1·16]; ten studies, 27 530 183 individuals), rates of hospital attendance for asthma exacerbations (-9·83% [-16·62 to -3·04]; five studies, 684 826 events), and rates of hospital attendance for all respiratory tract infections (-3·45% [-4·64 to -2·25]; two studies, 1 681 020 events) and for lower respiratory tract infections (-18·48% [-32·79 to -4·17]; three studies, 887 414 events). Associations appeared to be stronger when comprehensive smoke-free laws were implemented than when partial smoke-free laws were implemented. Among two studies assessing the association between smoke-free legislation and perinatal mortality, one showed significant reductions in stillbirth and neonatal mortality but did not report the overall effect on perinatal mortality, while the other showed no change in perinatal mortality. Meta-analysis of studies on other MPOWER policies was not possible; all four studies on increasing tobacco taxation and one of two on offering disadvantaged pregnant women help to quit smoking that reported on our primary outcomes had positive findings. Assessment of publication bias was only possible for studies assessing the association between smoke-free legislation and preterm birth, showing some degree of bias.

INTERPRETATION

Smoke-free legislation is associated with substantial benefits to child health. The majority of studies on other MPOWER policies also indicated a positive effect. These findings provide strong support for implementation of such policies comprehensively across the world.

FUNDING

Chief Scientist Office Scotland, Farr Institute, Netherlands Lung Foundation, Erasmus MC.

Smoke-free legislation and child health

In this paper, we aim to present an overview of the scientific literature on the link between smoke-free legislation and early-life health outcomes. Exposure to second-hand smoke is responsible for an estimated 166 ,000 child deaths each year worldwide. To protect people from tobacco smoke, the World Health Organization recommends the implementation of comprehensive smoke-free legislation that prohibits smoking in all public indoor spaces, including workplaces, bars and restaurants. The implementation of such legislation has been found to reduce tobacco smoke exposure, encourage people to quit smoking and improve adult health outcomes. There is an increasing body of evidence that shows that children also experience health benefits after implementation of smoke-free legislation. In addition to protecting children from tobacco smoke in public, the link between smoke-free legislation and improved child health is likely to be mediated via a decline in smoking during pregnancy and reduced exposure in the home environment. Recent studies have found that the implementation of smoke-free legislation is associated with a substantial decrease in the number of perinatal deaths, preterm births and hospital attendance for respiratory tract infections and asthma in children, although such benefits are not found in each study. With over 80% of the world’s population currently unprotected by comprehensive smoke-free laws, protecting (unborn) children from the adverse impact of tobacco smoking and SHS exposure holds great potential to benefit public health and should therefore be a key priority for policymakers and health workers alike.