Survival analytical techniques were used to assess agreement of a quantitative variable

Background and Objective: Survival-agreement plots have been suggested as a new graphical approach to assess agreement in quantitative variables. We propose that survival analytical techniques can complement this method, providing a new analytical insight for agreement. Methods: Two survival-agreement plots are used to detect the bias between to measurements of the same variable. The presence of bias is tested with log-rank test, and its magnitude with Cox regression. Results: An example on C-reactive protein determinations shows how survival analytical methods would be interpreted in the context of assessing agreement. Conclusion: Log-rank test, Cox regression, or other analytical methods could be used to assess agreement in quantitative variables; correct interpretations require good clinical sense. (C) 2005 Elsevier Inc. All rights reserved.