Identifying the appropriate threshold of baseline Kt/V by the generalized additive models (GAM) plot.

Abstract

<p>(A) The GAM plot adjusted for the important covariates at baseline only (gender, Kt/V, use of high-flux dialyzer, pruritus intensity, hematocrit, creatinine, uric acid, fasting glucose, total bilirubin, and Ca×P).(B) The GAM plot adjusted for the important covariates at baseline (Kt/V, pruritus intensity, AST, and Ca×P) and the change scores of the covariates (uric acid, fasting glucose, and AST). The solid red lines show nonlinearity of multivariable-adjusted relation between baseline Kt/V and change score of pruritus (with 95% confidence intervals shown in black dotted lines). Pruritus intensity was assessed by visual analog scale scores. The little vertical bars (i.e., rugs) on the horizontal axis of the GAM plots display the distribution of individual observations. Both GAM plots identified the value around 1.5 to be the appropriate threshold of baseline Kt/V for uremic pruritus, which indicated start of the aggravation of pruritus intensity began at Kt/V <1.5.</p