The prospective OPAL study enrolling 154 critically ill adults from six sites in the USA used two clinical cut-off values for urinary [TIMP-2]*[IGFBP7] based on the data from the SAPPHIRE cohort: A low (0.3) and a high (2.0) cut-off value were chosen to achieve either a high sensitivity or a high specificity to identify patients who are at high risk for AKI, respectively [10]. Here, TIMP2 is linked to acute kidney injury.