gms | German Medical Science

Introduction: Kidney function is an established risk factor for cardiovascular disease (CVD) events [1]. In a high risk CVD population it had been suggested that cystatin C based equations to estimate glomerular filtration rate (eGFR) show better prognostic value than creatinine (Cr) based ones [2]. However, in population-based settings the situation is less clear. In addition it is controversial whether albuminuria carries additional information. The aim of this study was to estimate the association of Cr- and cystatin C-based eGFR and albuminuria with CVD in a population of older adults.

Material & methods: The study included participants, aged 50–75 years, of a statewide cohort study (ESTHER) conducted in the state of Saarland. Stages of chronic kidney disease (CKD) were defined by the Cr based simplified Modification of Diet in Renal Disease (MDRD), the Chronic Kidney Disease Epidemiology (CKD-EPI), and by the cystatin C based Arnal-Dade estimating equations. Active follow-up was conducted after two and five years. The Cox proportional hazards model was used to estimate the risk of CKD-stages and albuminuria with nonfatal and fatal CVD events after adjustment for established risk factors.

Results: 9,411 patients (mean age 62.1 years, 55% females) with measurements of Cr and cystatin C and follow-up information were included in the analysis (95% of total). During follow-up (mean 4.8 years), 445 participants (4.7%) experienced a CVD event. CKD, assessed by the MDRD, CKD-EPI and Arnal-Dade equation, showed a prevalence of 17.4%, 17.6%, and 8.6%, respectively. Micro-and macroalbuminuria were prevalent in 9.1% and 2.7% of subjects, respectively. The adjusted (hazard ratio (HR)) for subsequent CVD events when subjects with CKD stage 3 (eGFR of 30-60 ml/min/1.73m2) and CKD stage 4-5 (eGFR < 30 mL/min/1.73m2) were compared to subjects with a normal eGFR (>=90 ml/min/1.73m2) for MDRD was 1.47 [95% CI, 1.12-1.94] and 2.24 [95% CI 0.81-6.21], for CK-EPI the HR was 1.40 [95% CI, 1.06-1.86) and 1.54 [95% CI 0.61-3.85], and for Arnal-Dade the HR was 1.56 [95% CI, 1.14-2.14) and 2.35 [95% CI 1.05-5.23], respectively. Micro- and macroalbumiuria remained statistically significant in the multivariable model even after inclusion of Cr or cystatin C based eGFR.

Conclusion: CKD stages 3 to 5, estimated by the cystatin C-based eGFR equation, showed a stronger association with CVD outcomes than the same CKD stages estimated by commonly used Cr-based ones. Notably, albuminuria carried additional prognostic information for subsequent CVD risk in this elderly population.