What Is the Goal With Endogenous Filtration Markers—Estimation of GFR or Prediction of Kidney Outcomes?

Clinical implications and predictive value of the creatinine‑cystatin C ratio in patients with multiple myeloma and renal impairment

The creatinine (Cr)-cystatin C ratio (CCR) at the time of cancer diagnosis is associated with survival; however, to the best of our knowledge, the association between this ratio and mortality in patients with multiple myeloma and renal impairment (RI) is unclear. Therefore, the present study aimed to assess this association, as well as disease prognosis and the clinical significance of the CCR in patients with multiple myeloma and RI. The present retrospective study included 191 patients diagnosed with multiple myeloma and RI between 2012 and 2022. The predictive value of the CCR was evaluated using area under the receiver operating characteristic curve (AUC) values. The factors affecting overall survival (OS) were assessed using uni- and multivariate logistic regression analyses. The effect of the CCR on survival was evaluated using a Cox regression model and the Kaplan-Meier method. There was a significant association between low CCR and poor progression-free survival (PFS) and overall survival (OS). The 1-, 2- and 3-year PFS and OS rates in patients with a low CCR were significantly lower than those in patients with a high CCR. The 1-, 2- and 3-year AUC values of the CCR were 0.712, 0.764 and 0.746 respectively. Multivariate analysis revealed sex, age, Cr levels, CCR and C-reactive protein levels as independent prognostic factors affecting OS rates. The CCR is a potential prognostic indicator in patients with multiple myeloma with RI and is associated with clinical stages.

Serum creatinine to cystatin C ratio and clinical outcomes in adults with non-dialysis chronic kidney disease

Background

Studies have suggested that the serum creatinine/cystatin C (Cr/CysC) ratio is a surrogate marker for muscle wasting is associated with adverse outcomes in several disease conditions. To clarify the utility of the Cr/CysC ratio as a prognostic marker in chronic kidney disease (CKD) we evaluated the association between the Cr/CysC ratio clinical outcomes in patients with non-dialysis CKD.

Methods

This prospective observational cohort study included 1,966 participants of the KoreaN cohort study Outcomes in patients With CKD (KNOW-CKD). We evaluated associated factors with the serum Cr/CysC ratio and association between the serum Cr/CysC ratio and composite outcomes of all-cause death and cardiovascular events (CVEs).

Results

The mean age was 54 ± 12 (SD) years and 61% were men. The mean serum Cr/CysC ratio was 10.97 ± 1.94 in men and 9.10 ± 1.77 in women. The Cr/CysC ratio correlated positively with urinary creatinine excretion, a marker of muscle mass. In the fully adjusted Cox proportional hazard model, the Cr/CysC ratio was associated with the occurrence of adverse outcomes through a median follow-up of 5.9 years [hazard ratio (HR) = 0.92, 95% confidence interval (CI) = 0.85–0.99 for the composite outcomes, HR = 0.87, 95% CI, 0.78 − 0.97 for all-cause death, and HR = 0.93; 95% CI, 0.84–1.04 for CVEs]. In subgroup analyses, there were interactions of the Cr/CysC ratio with age and sex for risk of the clinical outcomes, but not eGFR group.

Conclusion

A higher Cr/CysC ratio is associated with a lower risk of the composite outcomes, especially all-cause mortality, even after adjusting for eGFR. These suggest that the Cr/CysC ratio is a useful prognostic marker in CKD.

β-Trace protein: a marker of GFR and other biological pathways

β-Trace protein (BTP), also known as lipocalin prostaglandin D2 synthase (L-PGDS; encoded by the PTGDS gene), is a low-molecular-weight glycoprotein and an emerging novel marker of glomerular filtration rate. BTP is an important constituent of cerebral spinal fluid and is found in much lower concentrations in blood. Its serum origin and renal handling remain poorly understood. Unlike serum creatinine, BTP is not physiologically inert. It possesses both ligand-binding and enzymatic properties. BTP catalyzes the conversion of prostaglandin H2 (PGH2) to PGD2. PGD2 is an eicosanoid involved in a variety of important physiologic processes, including platelet aggregation, vasodilation, inflammation, adipogenesis, and bone remodeling. Several studies now have documented BTP's strong association with glomerular filtration rate, end-stage renal disease, cardiovascular disease, and death in a variety of different patient populations. This review provides an overview of the biochemistry, physiology and metabolism, biological functions, and measurement of BTP; summarizes the evidence for BTP as a marker of both kidney function and cardiovascular disease; and then considers the interplay between its biological properties, serum concentration, and patient outcomes.