Investigators at the Brigham looked at 1,783 inpatients and outpatients who had cystatin C and creatinine levels drawn within 24 hours from January 1, 2018 until September 9, 2020. They evaluated how cystatin C eGFR correlated with creatinine eGFR and how it indicated differences in CKD staging.
They found that cystatin C-based eGFR was strongly correlated with creatinine-based eGFR and that 27 percent of patients would be classified as having a more severe chronic kidney stage based on cystatin C test results; the likelihood of having a change in stage was higher among patients who had kidney function on the border between stages.
Cystatin C as a Marker for GFR
Researchers also found that Black patients were less likely to be reclassified to a more severe stage than White patients, but there were limitations in the self-identified race data. These results are important, as Black, Hispanic, and Native American patients have been shown to have less timely nephrology referrals, transplant access, home dialysis treatment and increased progression to kidney failure.
“Nationally, there should be a focus on making this important test affordable and accessible to a wide, diverse spectrum of patients,” said Mallika Mendu, MD, Associate Chief Medical Officer, Associate Professor of BWH’s Nephrology Division, and senior author of the study.