Table 5.

Lessons concerning the credibility of subgroup effects

A subgroup effect is credible (23) when:
It is relatively large and highly statistically significant.
 It is one of a small group of prespecified hypotheses tested.
 The test of treatment×subgroup interaction is significant.
 It is consistent with other reports (33).
 It is consistent across related outcomes (19).
 The biologic rationale is plausible.