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Systematic reviews to evaluate causation: an overview of methods and application
Khalid S Khan1, Elizabeth Ball, Caroline E Fox
1Department of Obstetrics and Gynaecology, Royal London Hospital, London, UK. k.s.khan@qmul.ac.uk
Evidence-Based Medicine
|April 12, 2012
Summary
Systematic reviews can evaluate disease causation by examining evidence for causal criteria. This approach synthesizes data to determine if observed associations are truly causal, advancing medical understanding.
Area of Science:
- Medical research methodology
- Epidemiology
- Causal inference
Background:
- Systematic reviews traditionally focus on diagnosis or treatment effectiveness.
- Understanding disease aetiology (causation) is fundamental to medical education, practice, and research.
- Qualitative assessment of causal criteria is common but can be enhanced by systematic evidence synthesis.
Purpose of the Study:
- To outline a systematic approach for evaluating disease aetiology and mechanisms using evidence synthesis.
- To detail the application of causal criteria within systematic reviews for establishing disease causation.
- To highlight the need for rigorous methods in assessing disease causality.
Main Methods:
- Specify research questions addressing causal criteria (strength, consistency, temporality, specificity, biological gradient, plausibility, experimental evidence).
- Conduct thorough literature searches and assess study quality, focusing on bias, exposure, and outcome ascertainment.
- Synthesize data using meta-analysis, heterogeneity testing, and meta-regression to evaluate associations.
- Systematically assess biological plausibility and coherence with existing scientific literature.
- Collate and synthesize experimental evidence to determine if causal agent removal impacts outcomes.
Main Results:
- A systematic review framework can rigorously assess evidence for disease causation.
- Quantitative synthesis methods like meta-analysis can strengthen causal inference.
- The framework allows for systematic evaluation of all established causal criteria.
Conclusions:
- Systematic reviews offer a robust methodology for evaluating disease aetiology beyond traditional diagnostic or treatment effectiveness reviews.
- This evidence synthesis approach can systematically determine whether observed associations are causal.
- Applying these methods advances the understanding of disease mechanisms and supports evidence-based medicine.
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