NEET PG High-Yield: Hill’s Criteria for Causation
To establish a causal link rather than a simple association, Sir Austin Bradford Hill proposed these nine criteria. Temporality is the only one that is essential.
| Criterion | Description |
|---|---|
| 1. Temporality | Exposure must precede the outcome. (Mandatory) |
| 2. Strength | Large effect size (Relative Risk/Odds Ratio). |
| 3. Consistency | Findings repeated in different settings and populations. |
| 4. Specificity | Specific exposure causes a specific disease. |
| 5. Dose-Response | Increasing exposure increases the risk of the outcome. |
| 6. Biological Plausibility | Logical explanation supported by current science. |
| 7. Coherence | Findings do not conflict with known natural history. |
| 8. Experiment | Removal of exposure leads to a decrease in outcome. |
| 9. Analogy | Similar effects seen with similar exposures. |
Types of Associations
| Type | Description |
|---|---|
| Spurious | False association due to chance, bias, or confounding. |
| Indirect | Link exists due to an intermediary factor (confounder). |
| Direct (Causal) | Exposure leads to disease without an intermediate step. |
High-Yield NEET PG Pearl:
Remember the mnemonic “T-S-C-S-D-P-C-E-A”. While all contribute to the weight of evidence, Temporality is the absolute prerequisite for causality.
To establish causation, look for these criteria (most important is Temporality):
- Temporality: The cause must precede the effect.
- Strength of Association: Higher RR/OR increases likelihood.
- Consistency: Repeated findings in different populations.
- Dose-Response: More exposure = higher risk.
- Biological Plausibility: Fits current biological/medical knowledge.