A meta-analysis of 10 RCTs shows a pooled RR of 0.75 (95% CI: 0.60–0.95) for a drug reducing MI. The I² statistic is 68%. What is the correct interpretation?
- A Substantial heterogeneity exists; the pooled estimate should be interpreted with caution ✓
- B The drug is ineffective; CI crosses 1.0
- C I² >50% proves publication bias
- D I² >50% invalidates the meta-analysis entirely
Correct answer: A. Substantial heterogeneity exists; the pooled estimate should be interpreted with caution
Explanation
I² of 68% indicates substantial heterogeneity (thresholds: <25% low, 25–50% moderate, 50–75% substantial, >75% considerable). The pooled RR is statistically significant (CI does not cross 1.0), but wide variation in individual study results means the pooled estimate may not represent a single true effect. A random-effects model and pre-specified subgroup analyses are warranted to explore sources of heterogeneity.
Reference: Park's Textbook of Preventive and Social Medicine, 27th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.