Fig. 3.

PCA identifies diagnostic and prognostic potential of the modelling cytokine profiles in idiopathic inflammatory myopathies. PCA increases the ability to identify uncorrelated features and interpret and analyse the profiles by reducing dimensionality. (A) PCA was performed on the training set and the test data applied to this model had an area under the curve of 0.75, indicating the remarkable discriminatory power of the model. (B) In order to assess the prognostic power of the model identified by the PCA, we investigated the role of PCA modulatory cytokines in the therapeutic response of a patient with active JDM. The data, which were rescaled so that the value of 0 characterizes the level of healthy controls to create a cytokine activity score, were plotted over time during treatment to assess patient response. Changes for PC3 correlated well with clinical response as early as 2 weeks of therapy, and therefore indicate the prognostic potential of the model in IIM.