A systematic review of randomized controlled trials reports that a new antihypertensive drug reduces cardiovascular events. The I² statistic is calculated as 78%. Which conclusion is MOST appropriate regarding this meta-analysis?
- A Results can be pooled as I² < 80%
- B Substantial heterogeneity exists; a random-effects model is preferable, and clinical homogeneity should be investigated ✓
- C The meta-analysis should be discarded because heterogeneity exceeds 50%
- D Fixed-effects model is appropriate as I² reflects precision, not heterogeneity
Correct answer: B. Substantial heterogeneity exists; a random-effects model is preferable, and clinical homogeneity should be investigated
Explanation
I² quantifies the proportion of total variation across studies due to true heterogeneity rather than chance. Values of 25%, 50%, and 75% represent low, moderate, and high heterogeneity. An I² of 78% indicates substantial heterogeneity; a random-effects model, which accounts for between-study variation, is more appropriate than fixed-effects. Investigators should explore causes (subgroup analyses, meta-regression) rather than discard the review. The study should not be discarded solely on this basis.
Reference: Park's Textbook of Preventive and Social Medicine, 27th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
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