Different eGFR markers and prediction of cardiovascular risk.

BACKGROUND: Renal dysfunction increases cardiovascular (CV) risk. We compared cystatin C-based estimated glomerular filtration rate (eGFRcys), creatinine-based eGFR (eGFRcr), and their ratio (eGFRcys/eGFRcr) in relation to major adverse cardiovascular events (MACE) and all-cause mortality in chronic coronary syndrome, assessing the added prognostic value of the eGFRratio. METHODS: In this post hoc analysis of 14,513 Stabilization of Atherosclerotic Plaque by Initiation of Darapladib Therapy trial patients, we investigated associations between baseline eGFRcys, eGFRcr, their ratio, and MACE and all-cause death using Cox regression models, unadjusted and adjusted for eGFRcys, eGFRcr, and their combination. Discrimination was assessed using Harrell's C-index; added value by the fraction of new information (FNI). RESULTS: Median age was 65 years; 82% were male. Median eGFRcys was 77 (interquartile range [IQR]: 61-94) and eGFRcr 79 (IQR: 65-91) mL/min/1.73 m2. Over 3.7 years, 1449 MACE and 1063 deaths occurred. Lower eGFR values and eGFRratio were associated with increased MACE risk, primarily driven by CV death. For eGFRcys 60 versus 90, the hazard ratio (HR) for MACE adjusted for eGFRcr was 1.77 (95% CI: 1.49-2.09, FNI 54%). In contrast, eGFRcr adjusted for eGFRcys showed no positive association (HR 0.82, 95% CI: 0.68-0.97, FNI 3%). A lower eGFRratio was linked to higher MACE risk (HR 1.99, 95% CI: 1.80-2.21), which remained after eGFRcr adjustment (HR 1.89, 95% CI: 1.70-2.10, FNI 54%) but was attenuated after eGFRcys adjustment (HR 1.29, 95% CI: 1.13-1.46, FNI 5%). CONCLUSION: In chronic coronary syndrome, lower eGFRcys, eGFRcr, and eGFRratio were associated with higher MACE and mortality risk. eGFRcys had the strongest association; eGFRcr and eGFRratio added limited incremental value.