Fig. 3.

(A–B). Restricted cubic splines (RCS) demonstrating the association between protein-adjusted serum free thiols and the risk of incident CKD for both (A) the crude model (Model 1) and (B) the fully adjusted model (Model 4). Estimated associations were derived from Cox proportional hazards regression models and RCS based on three knots (0.5th, 50th and 99.5th percentiles). Likelihood ratio tests for non-linearity were not significant for both models (χ² =1.32, P=0.287 and χ² =1.11, P=0.292, respectively). Orange- and red-shaded areas represent 95% confidence intervals. (For interpretation of the references to colour in this figure legend, the reader is referred to the Web version of this article.)