Chronic Kidney Disease Classification in Systolic Blood Pressure Intervention Trial: Comparison Using Modification of Diet in Renal Disease and CKD-Epidemiology Collaboration Definitions.

backgroundInterventional trials have used either the Modification of Diet in Renal Disease (MDRD) or chronic kidney disease (CKD)-Epidemiology Collaboration (CKD-EPI) equation for determination of estimated glomerular filtration rate (eGFR) to define whether participants have stages 3-5 CKD. The equation used to calculate eGFR may influence the number and characteristics of participants designated as having CKD.

methodsWe examined the classification of CKD at baseline using both equations in the Systolic Blood Pressure Intervention Trial (SPRINT). eGFR was calculated at baseline using fasting serum creatinine values from a central laboratory.

resultsAmong 9,308 participants with baseline CKD classification using the 4-variable MDRD equation specified in the SPRINT protocol, 681 (7.3%) participants were reclassified to a less advanced CKD stage (higher eGFR) and 346 (3.7%) were reclassified to a more advanced CKD stage (lower eGFR) when the CKD-EPI equation was used to calculate eGFR. For eGFRs <90 ml/min/1.73 m2, participants <75 years were more likely to be reclassified to a less advanced CKD stage; this reclassification was more likely to occur in non-blacks rather than blacks. Participants aged ≥75 years were more likely to be reclassified to a more advanced than a less advanced CKD stage, regardless of baseline CKD stage. Reclassification of baseline CKD status (eGFR <60 ml/min/1.73 m2) occurred in 3% of participants.

conclusionsUse of the MDRD equation led to a higher percentage of participants being classified as having CKD stages 3-4. Younger and non-black participants were more likely to be reclassified as not having CKD using the CKD-EPI equation.