Introduction

There is considerable interest in raising the age of sale of tobacco above the conventional age of 18. We systematically reviewed 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.

Methods

Following a pre-registered protocol on PROSPERO (ref: CRD42022347604), six databases of peer-reviewed journals were searched from January 2015 to April 2024. Backwards and forwards reference searching was conducted. Included studies assessed the association between MLSAs ≥20 with cigarette smoking or cigarette sales for those aged 11-20. Assessments on e-cigarettes were excluded. Pairs of reviewers independently extracted study data. We used ROBINS-I to assess risk of bias and GRADE to assess quality of evidence. Findings were also synthesised narratively.

Results

23 studies were reviewed and 34 estimates of association were extracted. All extracted studies related to Tobacco 21 laws in the United States. Moderate quality evidence was found for reduced cigarette sales, moderate quality evidence was found for reduced current smoking for 18 - 20 year olds, and low quality evidence was found for reduced current smoking for 11 - 17 year olds. The positive association was stronger for those with lower education. Study bias was variable.

Conclusions

There is moderate quality evidence that Tobacco 21 can reduce overall cigarette sales and current cigarette smoking amongst those aged 18- 20. It has potential to reduce health inequalities. Research in settings other than the United States is required.

Implications

This systematic review on raising the minimum legal sale age of tobacco to 20 or above demonstrates there is moderate quality evidence that such laws reduce cigarette sales, and moderate quality evidence they reduce smoking prevalence amongst those aged 18-20 compared to a minimum legal sale age of 18 or below. The research highlights potential benefits in reducing health inequalities, especially individuals from lower educational backgrounds. Studies are limited to the United States, highlighting a need for more global research to assess the impact of these policies in other settings.