Caution should be used in applying propensity scores estimated in a full cohort to adjust for confounding in subgroup analyses: commentary on "Applying propensity scores estimated in a full cohort to adjust for confounding in subgroup analyses": Commentary on "Applying propensity scores estimated in a full cohort to adjust for confounding in subgroup analyses" Pharmacoepidemiol Drug Saf. 2012 Jul; 21(7):710-712.