INS and acute kidney injury: Before matching, there were imbalanced distributions within the ASSESS-AKI data set (68 PPI users and 1470 PPI non-users) with respect to center (SMD = 0.316), gender (SMD = 0.109), race (SMD = 0.346), age (SMD = 0.273), hypertension (SMD = 0.159), diuretics use (SMD = 0.218) and insulin use (SMD = 0.147).