Figure 4.

A one latent variable PLSDA model based on two rounds of VIP selection from serum and sputum proteins and blood flow markers shows clear differentiation between stable and exacerbation events across 8 pairs of patient samples, which included 7 paired stable and AE-COPD events experienced by 6 unique patients and one stable and one exacerbation measurement that were not patient matched. (a) PLSDA and two rounds of VIP analysis identified a signature of eleven factors that differentiated the stable (purple) from the exacerbation (orange) events, with 87.5% calibration and cross-validation accuracy. Latent variable 1 (LV1) accounted for 41.51% of the variance in the data. The scores plot shown is based on a two latent variable model to enable better visualization of group separation. (b) The loadings plot highlights factor contributions to the VIP-selected signature, with positive loadings positively associated with AE-COPD, and negative loadings comparatively reduced during an exacerbation event.