**7. Conclusions**

CKD is a growing public health problem with high morbidity and mortality. The current classification considers the eGFR and albuminuria levels to classify patients in prognostic categories. Novel biomarkers were also developed to improve risk stratification and clinical decision-making, as well as guide CKD patient enrichment in clinical trials. Despite the great efforts made, only a few biomarkers found a large clinical application to date. More emphasis should be placed on the development process of biomarkers, which needs to be methodologically rigorous, well validated, and correctly diffused. A "real-world" assessment of biomarkers that can be performed by analyzing large databases with long-term follow-up may substantially contribute to understanding whether a definite biomarker can find clinical application. The implementation of biomarkers in CKD is highly expected in the future, since they provide information on the mechanisms of kidney disease, improve clinical practice, and, in most cases, are able to forecast both CV and renal endpoints, which represent the most frequent events in CKD patients.

**Author Contributions:** Conceptualization, M.P., S.R., I.G., and M.A.; methodology, M.P., S.R., P.C. and M.A.; validation, M.P., S.R., I.G., A.M., E.A., S.B., R.S., D.F., G.D.S., and M.A.; writing—original draft preparation, M.P., S.R., I.G., A.M., G.D.S., and M.A.; writing—review and editing, M.P., S.R., P.C., I.G., A.M., G.D.S., and M.A.; visualization, M.P., S.R., P.C., I.G., A.M., E.A., S.B., R.S., D.F., G.D.S., and M.A.; supervision, M.P. and M.A. All authors have read and agreed to the published version of the manuscript.

**Funding:** This research received no external funding.

**Acknowledgments:** We thank all the investigators of the "Magna Graecia" University of Catanzaro and the University of Campania "L. Vanvitelli", who collaborated on the manuscript, for their insight.

**Conflicts of Interest:** The authors declare no conflict of interest.
