how to use CASP (Critical Appraisal Skills Programme) RCT Checklist

How to Use the CASP (Critical Appraisal Skills Programme) RCT Checklist

The CASP RCT Checklist is a structured tool to critically appraise Randomized Controlled Trials (RCTs) for validity, reliability, and clinical relevance. It consists of 11 key questions divided into three sections:

1. Validity (Are the results trustworthy?)
2. Results (What are the findings?)
3. Applicability (Can the results be applied to your context?)

🔹 Step 1: Download the CASP RCT Checklist

• Get the free checklist here:
  🔗 https://casp-uk.net/casp-tools-checklists/

🔹 Step 2: Appraise the Study Using the 11 Key Questions

A. Validity (Questions 1-6)

1. Did the trial address a clearly focused research question?

• ✔ Look for PICO elements (Population, Intervention, Comparison, Outcome).
• ❌ If the question is vague (e.g., “Does treatment X work?”), it’s a weakness.

2. Was the assignment of participants randomized?

• ✔ Check if randomization was truly random (e.g., computer-generated).
• ❌ If randomization is unclear or not mentioned, downgrade credibility.

3. Were participants and researchers blinded (masked)?

• ✔ Look for double-blinding (participants & assessors unaware of treatment).
• ❌ If blinding was impossible (e.g., surgery vs. drug), note potential bias.

4. Were all participants accounted for at the study’s conclusion?

• ✔ Check attrition/dropout rates (≤20% is acceptable).
• ✔ Was Intention-to-Treat (ITT) analysis used?
• ❌ High dropout (>20%) or per-protocol analysis weakens reliability.

5. Were the groups similar at baseline?

• ✔ Compare baseline characteristics (age, gender, disease severity).
• ❌ Major imbalances suggest flawed randomization.

6. Were participants treated equally apart from the intervention?

• ✔ Check if co-interventions (e.g., additional drugs) were balanced.
• ❌ If one group received extra care, results may be biased.

B. Results (Questions 7-9)

7. How large was the treatment effect?

• ✔ Look for effect size (e.g., Relative Risk, Odds Ratio, Mean Difference).
• ✔ Check confidence intervals (CI)—narrow CIs = more precise results.

8. How precise was the estimate of the treatment effect?

• ✔ If 95% CI crosses “no effect” (RR=1 or MD=0), results may not be significant.

9. Were all important outcomes considered?

• ✔ Check if primary & secondary outcomes were pre-specified.
• ❌ If key outcomes (e.g., side effects) are missing, downgrade quality.

C. Applicability (Questions 10-11)

10. Can the results be applied to your local population?

• ✔ Compare study participants with your patients (age, comorbidities, setting).
• ❌ If the study used highly selected patients, generalizability may be limited.

11. Were all clinically important outcomes considered?

• ✔ Does the study report patient-relevant outcomes (e.g., survival, QoL)?
• ❌ If only surrogate markers (e.g., lab values) are used, clinical relevance is unclear.

🔹 Step 3: Summarize Your Appraisal

After answering all 11 questions, categorize the study as:
✅ High Quality (Mostly “Yes” answers, low risk of bias)
⚠ Moderate Quality (Some “Unclear” or minor flaws)
❌ Low Quality (Multiple “No” answers, high risk of bias)

🔹 Example CASP Appraisal

Final Rating: ⚠ Moderate Quality (Lack of blinding & missing harms data)

🔹 When to Use CASP RCT Checklist?

✔ Systematic reviews (to assess included studies).
✔ Clinical practice (to decide if evidence is trustworthy).
✔ Journal clubs (teaching critical appraisal skills).

🔹 Comparison with Other Tools

Final Tips

✅ Use alongside CONSORT to check reporting completeness.
✅ Involve multiple reviewers to reduce bias in appraisal.
✅ Document justifications for transparency.

Would you like a blank CASP checklist template for your reviews?