Figure 1.

Dendogram of hierarchical cluster analysis of variables. A synthetic variable is computed on the basis of principal component analysis for a mixture of continuous and categorical variables (PCAMIX). Variables are grouped based on the correlation with this variable. The cluster dendogram was cut (red line) into 11 clusters based on the agglomeration level and the Rand index. The dendogram height indicates the agglomeration level and thus lower height indicates more similarity. OCP = oral contraceptive pill; GI disorder = gastrointestinal disorder; EMF = dielectric heating; TENS = transcutaneous electrical nerve stimulation; CAD = coronary artery disease; ASA = ASA physical status classification system; HKAA = hip-knee-ankle angle; MS = metabolic syndrome; numbers indicate cluster number.