ACE and acute kidney injury: On the basis of the standardized mean difference shown in Figure 3, the key features of patients in Cluster 2, compared with Cluster 1, included: older age; a higher comorbidity burden, in particular hypertension; diabetes mellitus; coronary artery disease; lower eGFR; more acute kidney injury (AKI) at admission; more use of angiotensin converting enzyme inhibitors (ACEI)/angiotensin receptor blockers (ARB); and diuretics before admission.