Fig. 5

Multiple Factorial Analysis. Factorial planes for modalities and individuals. Legend: The first two dimensions were considered. Strong components were given by the type of BTcP, the intensity of BTcP, ECOG, Opioids, and metastases. Very poor contributions were finally detected for objective pain variables (red spots and labels): TTP, CDA SDHR, SDNN. The projection from the center to the variable's point revealed two key aspects including an orthogonal alignment with the existing variables' cloud pattern and a predominantly centralized contribution to FA2. Therefore, null correlations were confirmed between subjective variables (BTcP Intensity as NRS measure) and objective ones. The red arrow (zoomed mean of coordinates from the objective variables) points out the variable cloud shape, stating that poor correlations were detected. Each black point represents a variable modality which was plotted as “name of the variable”-underscore-modality: “N” = “No”, “Y” = “Yes”, “neuro” = “neuropathic”, “nocic” = “nociceptive”. Abbreviations: BMI, body mass index; ECOG, Eastern Cooperative Oncology Group performance status; BTcP, Breakthrough cancer pain; CDA, Continuous Decomposition Analysis; NRS, Numeric Rating Scale; TTP, Trough-To-Peak; SDRR, standard deviation R-R (interbeat intervals); SDHR, standard deviation heart rate; MED, Morphine Equivalent Dose