Fig. 4: Diagnostic performance of candidate serum lipid biomarkers for assessing RA activity and treatment outcome.

a OPLS-DA 2D score plots derived from models of moderate-to-high disease activity (DAS28 ≥ 3.2) and low disease activity or remission (DAS28 < 3.2) groups. b Validation of biomarker candidates from the discovery set identified by the t test (red) and OPLS-DA (blue). These biomarkers were used for biomarker analysis in the validation set. Area under the receiver operating characteristic (ROC) curve (AUC) analysis of the lipid biomarker candidates identified by the OPLS-DA and t test versus that for the C-reactive protein (as a comparator); parameters were evaluated for the ability to distinguish low disease activity from moderate/high disease activity, as determined by the DAS28 (green). The three compared areas are not significantly different. c Correlation between serum lipids and disease activity parameters. The exact value of the correlation coefficients is presented in a heatmap when absolute correlation coefficients are ≥0.3 (the p values for the correlation coefficient are <0.05). d Heatmap showing the expression of 37 significant lipids identified after comparison of paired samples obtained before and after treatment with DMARDs (samples compared using the t test).