To the Editor We read with interest the article by Wallis and colleagues,1 and we commend the authors for tackling this matter. Here, we offer some observations.
First, the sample excluded all sex-specific procedures to ensure sex-concordant and sex-discordant dyads were possible for all procedures, which excluded all obstetric and gynecologic surgeries. This exclusion may have biased the overall results concerning how sex modifies the association between dyad concordance and surgery outcomes in aggregate.