Impact of institutional smoking bans on reducing harms and secondhand smoke exposure

BackgroundSmoking bans or restrictions can assist in eliminating nonsmokers' exposure to the dangers of secondhand smoke and can reduce tobacco consumption amongst smokers themselves. Evidence exists identifying the impact of tobacco control regulations and interventions implemented in general workplaces and at an individual level. However, it is important that we also review the evidence for smoking bans at a meso- or organisational level, to identify their impact on reducing the burden of exposure to tobacco smoke. Our review assesses evidence for meso- or organisational-level tobacco control bans or policies in a number of specialist settings, including public healthcare facilities, higher education and correctional facilities.ObjectivesTo assess the extent to which institutional smoking bans may reduce passive smoke exposure and active smoking, and affect other health-related outcomes.Search methodsWe searched the Cochrane Central Register of Controlled Trials (CENTRAL); MEDLINE, EMBASE, and the reference lists of identified studies. We contacted authors to identify completed or ongoing studies eligible for inclusion in this review. We also checked websites of state agencies and organisations, such as trial registries. Date of latest searches was 22nd June 2015.Selection criteriaWe considered studies that reported the effects of tobacco bans or policies, whether complete or partial, on reducing secondhand smoke exposure, tobacco consumption, smoking prevalence and other health outcomes, in public healthcare, higher educational and correctional facilities, from 2005 onwards.The minimum standard for inclusion was having a settings-level policy or ban implemented in the study, and a minimum of six months follow-up for measures of smoking behaviour. We included quasi-experimental studies (i.e. controlled before-and-after studies), interrupted time series as defined by the Cochrane Effective Practice and Organization of Care Group, and uncontrolled pre- and post-ban data.Data collection and analysisTwo or more review authors independently assessed studies for inclusion in the review. Due to variation in the measurement of outcomes we did not conduct a meta-analysis for all of the studies included in this review, but carried out a Mantel-Haenszel fixed-effect meta-analysis, pooling 11 of the included studies. We evaluated all studies using a qualitative narrative synthesis.Main resultsWe included 17 observational studies in this review. We found no randomized controlled trials. Twelve studies are based in hospitals, three in prisons and two in universities. Three studies used a controlled before-and-after design, with another site used for comparison. The remaining 14 studies used an uncontrolled before-and-after study design. Five studies reported evidence from two participant groups, including staff and either patients or prisoners (depending on specialist setting), with the 12 remaining studies investigating only one participant group.The four studies (two in prisons, two in hospitals) providing health outcomes data reported an effect of reduced secondhand smoke exposure and reduced mortality associated with smoking-related illnesses. No studies included in the review measured cotinine levels to validate secondhand smoke exposure. Eleven studies reporting active smoking rates with 12,485 participants available for pooling, but with substantial evidence of statistical heterogeneity (I² = 72%). Heterogeneity was lower in subgroups defined by setting, and provided evidence for an effect of tobacco bans on reducing active smoking rates. An analysis exploring heterogeneity within hospital settings showed evidence of an effect on reducing active smoking rates in both staff (risk ratio (RR) 0.71, 95% confidence interval ( CI) 0.64 to 0.78) and patients (RR 0.86, 95% CI 0.76 to 0.98), but heterogeneity remained in the staff subgroup (I² = 76%). In prisons, despite evidence of reduced mortality associated with smoking-related illnesses in two studies, there was no evidence of effect on active smoking rates (1 study, RR 0.99, 95% CI 0.84 to 1.16).We judged the quality of the evidence to be low, using the GRADE approach, as the included studies are all observational.Authors' conclusionsWe found evidence of an effect of settings-based smoking policies on reducing smoking rates in hospitals and universities. In prisons, reduced mortality rates and reduced exposure to secondhand smoke were reported. However, we rated the evidence base as low quality. We therefore need more robust studies assessing the evidence for smoking bans and policies in these important specialist settings