What is the relationship between raising the minimum legal sales age of tobacco above 20 and cigarette smoking? A systematic review

ABSTRACT Objectives To determine whether raising the minimum legal sales age of tobacco (MLSA) to 20 or above is associated with reduced prevalence of smoking compared to an MLSA set at 18 or below through systematic review. Design Following a pre-registered protocol on PROSPERO (ref: CRD42022347604), six databases were searched for studies that assessed the association between MLSAs of 20 and above and tobacco smoking or tobacco sales. Assessments on e-cigarettes were excluded. Two reviewers independently extracted study data and used ROBINS-I to assess the risk of bias. Narrative methods were used to synthesise findings. Setting Global, with no language restrictions. Subjects Children and young people aged 11-20. Main outcome measures Current cigarette smoking and cigarette sales. Results 19 studies were reviewed, from which 26 effect estimates were extracted. All studies evaluated Tobacco 21 laws in the United States. Just under half of estimates found a statistically significant association with reduced current cigarette smoking or sales, just over half found no statistically significant association and one estimate found an association with increased cigarette smoking. The positive association appeared to be stronger for older age groups, those from a Hispanic/Latinx background and those with lower education. The degree of study bias was variable. Conclusions There is evidence that raising the MLSA for tobacco to 21 reduces cigarette sales and current cigarette smoking amongst those aged 11-20. It may have the potential to reduce health inequalities. Further research beyond the United States would support generalisability to other settings. ### Competing Interest Statement The authors have declared no competing interest. ### Clinical Protocols ### Funding Statement This work was partly supported by NIHR award 302872 ### Author Declarations I confirm all relevant ethical guidelines have been followed, and any necessary IRB and/or ethics committee approvals have been obtained. Yes I confirm that all necessary patient/participant consent has been obtained and the appropriate institutional forms have been archived, and that any patient/participant/sample identifiers included were not known to anyone (e.g., hospital staff, patients or participants themselves) outside the research group so cannot be used to identify individuals. Yes I understand that all clinical trials and any other prospective interventional studies must be registered with an ICMJE-approved registry, such as ClinicalTrials.gov. I confirm that any such study reported in the manuscript has been registered and the trial registration ID is provided (note: if posting a prospective study registered retrospectively, please provide a statement in the trial ID field explaining why the study was not registered in advance). Yes I have followed all appropriate research reporting guidelines, such as any relevant EQUATOR Network research reporting checklist(s) and other pertinent material, if applicable. Yes All data produced in the present study are available in the supplementary materials.