Background There are strong structural and theoretical reasons to expect politics to be an important determinant of population health outcomes. However, the most recently available systematic review of the evidence linking key political features (welfare state generosity, political tradition along the left-right axis, democracy, and globalisation) and population health outcomes contains searches only up to April 2010. Considering only internationally comparative studies, it found preliminary evidence that pro-social political features predicted better population health, but more up to date evidence synthesis is required. Therefore, the aim of this study was to present an updated systematic review on the political determinants of population health.

Methods Ten academic bibliographical databases, including MEDLINE, EMBASE, and Sociological Abstracts, were searched using search terms based on ((democracy OR autocracy OR welfare regime OR welfare state OR welfare capitalism OR politics OR political tradition OR internationality OR globalization) AND (health OR health services OR population health OR public health OR health economics OR health expenditure)). Supplementary searches were also conducted on Google Scholar and in relevant bibliographies. The final search was conducted in November 2017. We considered full-text scholarly articles or book chapters assessing the relationship between at least one of our eligible political features (welfare state generosity, political tradition along the left-right axis, democracy, and globalisation) and any population health outcome in human populations, except healthcare spending. Standardised data extraction, risk of bias assessment and narrative synthesis were conducted. Proportionate second review was conducted.

Results 73 articles were identified from the previous 2010 review. Updated database searches yielded 43 356 records (35 207 unique) and supplementary searches yielded 55. Full-text screening was conducted on 255 publications, and 176 publications (176 studies) were included, of which 106 were newly identified by our 7-year update. 79/102 studies found that increased welfare state generosity predicted greater population health. 15/17 studies found this effect for left-of-centre political tradition, as did 34/44 for democracy. Half of identified studies suggested that globalisation may be detrimental for health. 85 studies were at low risk of bias, 89 moderate, none high, and two could not be assessed.

Conclusion The evidence shows politics to be an important determinant of population health outcomes. The public health community should engage more with the political determinants of health in research and advocacy. Further research on globalisation is required. While we provide a rigorous and timely update, resources prevented us from conducting a new systematic review from inception.