How much evidence is there that political factors are related to population health outcomes? An internationally comparative systematic review

OBJECTIVES: To provide a 7-year update of the most recent systematic review about the relationships between political features and population health outcomes. SETTING: Internationally comparative scholarly literature. DATA SOURCES: Ten scholarly bibliographic databases plus supplementary searches in bibliographies and Google Scholar were used to update a previous systematic review. The final search was conducted in November 2017. PRIMARY AND SECONDARY OUTCOME MEASURES: Any population health outcome measure, apart from healthcare spending. RESULTS: 73 unique publications were identified from the previous systematic review. The database searches to update the literature identified 45 356 raw records with 35 207 remaining following de-duplication. 55 publications were identified from supplementary searches. In total, 258 publications proceeded to full-text review and 176 were included in narrative synthesis. 85 studies were assessed at low risk of bias, 89 at moderate risk of bias and none at high risk of bias. Assessment could not be conducted for two studies that had only book chapters. No meta-analysis was conducted. 102 studies assessed welfare state generosity and 79 found a positive association. Of the 17 studies that assessed political tradition, 15 were found to show a positive association with the left-of-centre tradition. 44 studies assessed democracy and 34 found a positive association. 28 studies assessed globalisation and 14 found a negative association, while seven were positive and seven inconclusive. CONCLUSIONS: This review concludes that welfare state generosity, left-of-centre democratic political tradition and democracy are generally positively associated with population health. Globalisation may be negatively associated with population health, but the results are less conclusive. It is important for the academic public health community to engage with the political evidence base in its research as well as in stakeholder engagement, in order to facilitate positive outcomes for population health.