Determining baseline serum creatinine in harmonized criteria for kidney disease: unfinished business.

Standardized criteria for acute and chronic kidney disease (AKD and CKD, respectively), independent of underlying or concomitant disease, have been developed by international working groups and have been widely validated and adopted. Nonetheless, kidney disease is often underdiagnosed and when it is diagnosed, laboratory measures that determine the duration of kidney disease may not be available, which may result in failure to differentiate AKD and CKD, leading to important deficiencies in care. Chief among these limitations is a lack of information on historical measures of kidney function, which are necessary to determine the 'baseline' status. Analysis of simulated trajectories of serum creatinine and estimated glomerular filtration rate reveals that missing historical measures often result in misclassification of kidney disease, with implications for patients, clinicians and healthcare policy. Urgent action is required to address this 'unfinished business' to improve the detection and classification of kidney disease in clinical practice, research and public health.