Discordance Between Creatinine-Based and Cystatin C–Based Estimated GFR: Interpretation According to Performance Compared to Measured GFR

The Difference Between Cystatin C- and Creatinine-Based Estimated Glomerular Filtration Rate and Risk of Diabetic Microvascular Complications Among Adults With Diabetes: A Population-Based Cohort Study

“…Notably, screening for cystatin C routinely has been highly recommended by the U.S. National Kidney Foundation and the American Society of Nephrology ( 21 ). Consistent with this recommendation, two recent studies demonstrated that the combined creatinine-cystatin C eGFR equation performed better than equations based on either of the two markers and reinforced the need for more frequent cystatin C measurements in clinical settings ( 22 , 23 ). In our study, the associations between eGFRdiff and DMCs were still robust when adjusting for eGFRcr-cys/eGFRcys, which suggests that the associations are likely to be explained by non-GFR determinants rather than more accurate measures of kidney function.…”

Rounding creatinine, cystatin C or both: impact on discordance group assignment and GFR-estimating equation performance

“…With two US national kidney disease organizations recently advocating for more routine use of cystatin C [ 11 ], clinicians will increasingly face discordant values between eGFRcr and eGFRcys. Discordant values, currently an active area of research [ 4 , 5 , 8 , 10 , 12 ], imply that eGFRcr, eGFRcys or both differ from measured GFR. Our work sheds light on how using integers instead of real numbers for creatinine and cystatin C levels affects GFR estimation, highlighting one contributing factor to discordant eGFR values.…”

Discordance in Estimated GFR Among Hospitalized Older Adults

“…Wang et al 1 evaluated discordances in the estimated glomerular filtration rate (eGFR) based on creatinine (eGFRcr), cystatin C (eGFRcys), or their combination (eGFRcr-cys). They used data from the 2021 CKD-EPI external validation cohort, which included 4,050 ambulatory participants (mean age of 57.0 years and mean measured GFR [mGFR] of 76.4 mL/min/1.73m 2 ).…”

“…Our research focuses on hospitalized older adults, who are characterized by high rates of multimorbidity, frailty, malnutrition, and polypharmacy. 3 , 4 Given the unique patient population, we performed a similar analysis to Wang et al 1 for a previously described cohort of 106 hospitalized older adults with a mean age of 79.0 years and mGFR of 62.7 mL/min/1.73m 2 ( Table 1 ). 5 Using the 2009 eGFRcr equation (Danish standard), we found that 51% of patients had a negative discordance (67% when using 2021 eGFRcr), which is more than double that of Wang et al 1 and probably reflects differences in non-GFR determinants between cohorts.…”

“… 3 , 4 Given the unique patient population, we performed a similar analysis to Wang et al 1 for a previously described cohort of 106 hospitalized older adults with a mean age of 79.0 years and mGFR of 62.7 mL/min/1.73m 2 ( Table 1 ). 5 Using the 2009 eGFRcr equation (Danish standard), we found that 51% of patients had a negative discordance (67% when using 2021 eGFRcr), which is more than double that of Wang et al 1 and probably reflects differences in non-GFR determinants between cohorts. Like Wang et al, 1 we found that eGFRcr-cys outperformed both eGFRcr and eGFRcys in patients with a negative discordance.…”