Background: Recommended CKD first-line diagnostics is based on GFR-determination by Creatinine. Cystatin C-use may provide better assessment.
Methods: We compared creatinine- and cystatin C-derived eGFR determination in first-line di-agnostic of 112 hospital patients aged >60 years (median=76 years). Patients were judged kid-ney-sane according to first-line diagnostic recommendations (N=61, eGFR (CKD-EPI) ≥60ml/min/m2, total urine protein <150mg/g creatinine, urinary red and white blood cells not increased) or classified at-risk for kidney insufficiency due to aortic valve dysfunction (N=51). Plausibility of eGFR-values was evaluated retrospectively by final case diagnoses.
Results: eGFR (CAPA) was found linearly correlated to eGFR (CKD-EPI) (R2=0.5, slope=0.69, p<0.0001). In 93/112 (>80%) cases, eGFR (CAPA) yielded lower values (on average ≈20%). In 55/112 (49%) cases CKD-stage decreased. CKD-reclassification from kidney-sane to kid-ney-insufficient state (i.e. CKD1/2 to CKD3a/b or 4) or reclassification to more severe kidney in-sufficiency (i.e. CKD3a3b/4 or 3b4) was found in 41/112 (37%) cases. Worsening of CKD-classification (kidney-sanekidney-insufficient) based on eGFR (CAPA) was in 30% of cases plausible in the light of final case-diagnoses.
Conclusion: In elderly patients (>60 years), renal function appears systematically overestimated by creatinine-based eGFR (CKD-EPI) heralding for this group employment of cystatin C-based eGFR (CAPA) as first-line diagnostic.