If “placebo-resistant depression” and “treatment-resistant depression” were synonyms, we would expect that excluding treatment-resistant depression from your s

If “placebo-resistant depression” and “treatment-resistant depression” were synonyms, we would expect that excluding treatment-resistant depression from your study would result in the studying showing precisely no difference between treatment and placebo. The fact that the meta-analysis shows any difference at all suggests that “treatment-resistant depression” might be a meaningful category.