Discrepancy between cystatin C-based and creatinine-based eGFR predicts all-cause mortality in a community-based population: the Takahata study

Background Discrepancies between the cystatin C-based estimated glomerular filtration rate (eGFRcys) and the creatinine-based estimated glomerular filtration rate (eGFRcr) have been linked to adverse outcomes in Western populations. However, their prognostic significance in community-dwelling Japanese individuals remains unclear. Therefore, we conducted a prospective cohort study to evaluate this association. Methods We analyzed data from 1308 participants who underwent simultaneous measurements of serum creatinine and cystatin C levels between 2004 and 2006, with a median follow-up of 18.5 years. The discrepancy (eGFRdiff = eGFRcys − eGFRcr) was categorized into three groups: a low group (< − 10 mL/min/1.73 m 2 ), a reference group (− 10 to 10 mL/min/1.73 m 2 ), and a high group (≥ 10 mL/min/1.73 m 2 ). All-cause and cardiovascular mortality were assessed using Kaplan–Meier curves, Cox proportional hazards models, and restricted cubic spline analyses. Results During the follow-up period, 386 participants (29.5%) died, including 120 cardiovascular-related deaths. Compared with the reference group, individuals in the eGFRdiff < − 10 group exhibited a significantly higher risk of all-cause mortality (hazard ratio [HR]: 1.41; 95% confidence interval [CI]: 1.10–1.80), whereas those in the ≥ 10 group showed a lower risk (HR: 0.56; 95% CI: 0.33–0.97). No significant association was observed with cardiovascular mortality. Incorporating eGFRdiff into the baseline models improved discrimination for both all-cause and cardiovascular mortality. Conclusion The discrepancy between eGFRcys and eGFRcr levels is an independent predictor of all-cause mortality in a community-based Japanese population. eGFRdiff may serve as a simple yet informative marker for identifying individuals at increased risk of death.