Volume 76, Pages S3-S8 (August 2009) Chapter 1: Introduction and definition of CKD–MBD and the development of the guideline statements    Kidney International  Volume 76, Pages S3-S8 (August 2009) DOI: 10.1038/ki.2009.189 Copyright © 2009 International Society of Nephrology Terms and Conditions

Figure 1 Interpreting a surrogate outcome trial. When interpreting the validity of a surrogate outcome trial, consider the following questions: 1. Is there a strong, independent, consistent association between the surrogate outcome and the clinical outcome? This is a necessary but not, by itself, sufficient prerequisite. 2. Is there evidence from randomized trials in the same drug class that improvements in the surrogate outcome have consistently led to improvements in the clinical outcome? 3. Is there evidence from randomized trials in other drug classes that improvement in the surrogate outcome has consistently led to improvement in the clinical outcome? Both 2 and 3 should apply. This figure illustrates principles outlined in Users’ Guide for Surrogate Endpoint Trial3 and the legend is modified after this reference. Phosphate binders, calcification, and CVD are chosen as an example. CVD, cardiovascular disease. Kidney International 2009 76, S3-S8DOI: (10.1038/ki.2009.189) Copyright © 2009 International Society of Nephrology Terms and Conditions