Cystatin C-based estimated GFR performs best in identifying individuals with poorer survival in an unselected Chinese population: results from the China Health and Retirement Longitudinal Study (CHARLS)

Background The decline in estimated glomerular filtration rate (eGFR) has been reported as a risk factor for mortality. However, it remains unclear which eGFR equation is most useful in predicting death in the general Chinese population. Methods The association was examined between eGFR and all-cause mortality using data from the China Health and Retirement Longitudinal Study. Participants with complete data in 2011 and survival follow-up in 2013, 2015 and 2018 were included and analyzed in three separate cohorts, which included 8160, 8154 and 8020 participants, respectively. Logistic regression analyses, receiver operating characteristic curve, continuous net reclassification improvement (NRI) and integrated discrimination improvement (IDI) were computed to compare the discriminative power of eGFR derived by abbreviated Modification of Diet in Renal Disease (MDRD), Chinese coefficient-modified MDRD (MDRD-CN), Japanese coefficient-modified MDRD (MDRD-JPN), CKD-EPIcr, Japanese coefficient-modified CKD-EPIcr (CKD-EPIcr-JPN), CKD-EPIcys, CKD-EPIcr-cys, CKD-EPIcr fit without race and CKD-EPIcr-cys fit without race. Results A decreased eGFR (<60 ml/min/1.73 m(2)) was significantly associated with increased mortality at 2 years no matter which eGFR equation was used (odds ratio ranged between 2.02 and 4.94, all P < 0.001). The association remained significant after adjusting multiple covariates when MDRD-CN, CKD-EPIcys or CKD-EPIcr-cys fit without race was used. CKD-EPIcys showed the highest discriminative power for mortality (area under the curve 0.744 +/- 0.40) and outperformed other equations (all P < 0.001) except for CKD-EPIcr-cys. The overall risk classification was also improved when the CKD-EPIcys equation was adopted as indicated by continuous NRI and IDI. Similar results were observed at 4 and 7 years. Conclusions A decline in eGFR by all equations could predict poorer survival, among which the CKD-EPIcys equation showed the best discriminative power.