ABO blood type and ARDS.

First, the authors did not hypothesize that sex may modify the association between ABO blood type and ARDS risk. Previous studies found that women were more likely to develop ARDS compared with men, 2 whereas sex is not associated with ABO blood type distribution. Th us, it might be reasonable to hypothesize that the eff ects of ABO blood type on ARDS diff er between men and women. Because the authors had these data, more input could have been gained by carrying out additional analysis to investigate whether sex is an eff ect modifi er.