How to use SIGN (Scottish Intercollegiate Guidelines Network) Methodology Checklist for RCTs
How to Use the SIGN Methodology Checklist for RCTs
The Scottish Intercollegiate Guidelines Network (SIGN) provides a structured checklist to assess the methodological quality of randomized controlled trials (RCTs). It helps determine whether an RCT’s findings are reliable and valid for clinical decision-making.
Step-by-Step Guide
1. Access the SIGN Checklist
- Download the latest SIGN Methodology Checklist for RCTs from:
🔗 https://www.sign.ac.uk/what-we-do/methodology/checklists/
2. Understand the Key Appraisal Domains
The checklist evaluates internal validity (risk of bias) and overall reliability of an RCT. Key sections include:
A. Internal Validity (Bias Risk Assessment)
- Randomization
- Was the allocation sequence truly random?
- Was allocation concealment adequate?
- Blinding (Masking)
- Were participants, investigators, and outcome assessors blinded?
- Baseline Characteristics
- Were groups similar at baseline?
- Follow-up & Attrition
- Were all participants accounted for?
- Was intention-to-treat (ITT) analysis used?
- Outcome Measurement
- Were outcomes clearly defined and objectively measured?
B. Statistical & Clinical Relevance
- Were statistical methods appropriate?
- Are the results clinically meaningful?
3. Apply the Checklist to the RCT
For each question, answer:
✅ Yes (low risk of bias)
❌ No (high risk of bias)
❓ Unclear/Cannot say (insufficient information)
Example Assessment
| Question | Response | Justification |
|---|---|---|
| Was the randomization method clearly described and appropriate? | ✅ Yes | Computer-generated random sequence used. |
| Was allocation concealment maintained? | ❌ No | No mention of sealed envelopes or central randomization. |
| Were participants and personnel blinded? | ❓ Unclear | States “double-blind” but does not specify methods. |
| Were outcome assessors blinded? | ✅ Yes | Independent assessors unaware of treatment allocation. |
| Were dropouts/loss to follow-up <20%? | ✅ Yes | Only 5% attrition, balanced between groups. |
| Was an intention-to-treat (ITT) analysis performed? | ❌ No | Per-protocol analysis used instead. |
4. Assign an Overall Quality Rating
Based on responses, categorize the study as:
- ++ (High Quality): Minimal bias, reliable results.
- + (Acceptable Quality): Some weaknesses but unlikely to affect conclusions.
- – (Low Quality): Significant flaws, high risk of bias.
Example:
- Randomization: ✅
- Blinding: ❓
- Attrition: ✅
- ITT Analysis: ❌
➔ Overall Rating: + (Acceptable but with limitations)
5. Use the Appraisal in Evidence Synthesis
- Include only high-quality (++) studies in strong recommendations.
- Low-quality (–) studies may require cautious interpretation.
Key Tips for Effective Use
✔ Compare with other tools (e.g., Cochrane RoB 2, CASP) for cross-validation.
✔ Check for protocol deviations (e.g., ClinicalTrials.gov) to detect selective reporting.
✔ Use in systematic reviews or clinical guideline development.
Would you like a real-paper example assessed using SIGN?
