Reclassification of CKD Stage II–IV (CKD EPI Creatinine) Based on Cystatin C and Combined Cystatin C and Creatinine-based GFR Estimation (CKD EPI Cystatin C and Cystatin C + Creatinine) in Indian Population in a Tertiary Care Center

Aim: Equations for estimating the glomerular filtration rate (GFR) that incorporate both creatinine and cystatin C are more precise than using either eGFRcr or eGFRcys alone.Recent guidelines recommend using cystatin C as a confirmatory test when eGFRcr results might be unreliable.However, these guidelines do not specify the demographic or clinical scenarios where eGFRcys or eGFRcr-cys would be more accurate than eGFRcr, nor do they indicate which estimate should be used in such cases. Materials and methods:We evaluated the effectiveness of the chronic kidney disease epidemiology collaboration (CKD-EPI) equations, specifically eGFRcr-cys and eGFRcys, against eGFRcr in a cohort of 200 individuals from India.The data were gathered using the CKD-EPI creatinine stages II-IV for participants aged 18 and older, both male and female, after obtaining a thorough medical history.We excluded individuals with uncontrolled diabetes mellitus, hypertension, hypothyroidism, autoimmune diseases, morbid obesity, cancer, substance abuse, and those experiencing rapid deterioration of kidney function. Results: Of the 107 cases of CKD-EPI Cr stage II, 54 (51%) remained in CKD-EPI CysC stage II and 67 (62%) remained in CKD-EPI Cr-CysC stage II.Of the 41 cases of CKD-EPI Cr stage IIIa, 5 (12%) remained in CKD-EPI CysC stage IIIa and 13 (32%) remained in CKD-EPI Cr-CysC stage IIIa.Of the 36 cases of CKD-EPI Cr stage IIIb, 8 (22%) remained in CKD-EPI CysC stage IIIb and 11 (30%) remained in CKD-EPI Cr-CysC stage IIIb.Of the 16 cases of CKD-EPI Cr stage IV, 9 (56%) remained in CKD-EPI CysC stage and 11 (69%) remained in CKD-EPI Cr-CysC stage IV.Conclusion: The newly developed creatinine-cystatin C equation estimated GFR with minimal bias and demonstrated enhanced precision and accuracy in our Indian cohort.This dual-biomarker equation could potentially improve the accuracy of CKD population studies.