Introduction

1. Were the purposes/objectives of the study clear? Methods 2. Was the study design appropriate for the stated objectives? 3. Was the sample size justified? 4. Was the target/reference population clearly defined? (Is it clear who the research was about?) 5. Was the sampling frame taken from a population base appropriate to faithfully represent the target/reference population under investigation? 6. Was the selection process likely to recruit subjects/participants representative of the target/reference population under investigation? 7. Were measures taken to address and categorize non-responders? 8. Were the risk factors and outcome variables measured appropriately for the objectives of the study? 9. Were the risk factors and outcome variables properly measured using instruments/measures that had been previously tested, validated, or published? 10. Is it clear what was used to determine statistical significance and/or precision estimates? (e.g., p-values, CIs) 11. Were the methods (including statistical methods) sufficiently described to allow replication? Results 12. Were the baseline data adequately described? 13. Does the response rate raise concerns about non-response bias? 14. If applicable, was information about non-responders described? 15. Were the results internally consistent? 16. Were the results of the analyses described in the methods presented? Discussion 17. Were the authors’ discussions and conclusions justified by the results? 18. Were the study’s limitations discussed? Other 19. Were there any sources of funding or conflicts of interest that could affect the authors’ interpretation of the results? 20. Was ethical approval or participant consent obtained?

Note: Quality Scoring: Low = < 12.5 points, Medium = 12.5–15, High > 15 points.