Table 2 Classification of the evidence
Colour code | Standardized statement | Situations included |
|---|---|---|
1. White | Unknown effect: Insufficient published research on the intervention’s effect on the outcome. | No RCTs, one low quality RCT with any result, or |
One moderate-to-high quality RCT where 95% CI of the RR includes 1, or | ||
Only narrative reporting | ||
2. Grey | Unknown effect: Inconclusive published research on the intervention’s effect on the outcome. | At least two RCTs, 95% CI of the point estimate for a relative risk crosses widely on both sides of 1 (ranges from < 0.5 to > 2) |
3. Green | Positive effect: The intervention likely reduces the risk of the adverse outcome. | At least two moderate-to-high quality RCTs included in a meta-analysis or IPD analysis, 95% CI of the point estimate of the RR is entirely below 1 |
4. Yellow | Possible positive effect: The intervention may reduce the risk of the adverse outcome. | At least two RCTs included in a meta-analysis or IPD analysis, 95% CI of the point estimate of the RR is entirely below 1, but there is concern about the quality of the data, or |
at least two moderate-to-high quality RCTs included in a meta-analysis or IPD analysis, 95% CI of the point estimate of the RR includes 1 but 90% CI of the point estimate of the RR is entirely below 1, or | ||
One moderate-to-high quality RCT, 95% CI of the point estimate of the RR is entirely below 1 | ||
5. Red | No positive effect: The intervention is not likely to reduce the risk of the adverse outcome. | Other situations, including meta-analysis results suggestive of harm |