Table 1. Decision rules (separated by lines) extracted from the CART classifier, providing a semantic description of the pain phenotypes (clusters #1–#4) found by Ward cluster analysis.

Case belongs to		IF (Rule conditions)
Cluster #1:	(IF	CO2 intensity ≤42. 5 mm VAS
	AND)	Heat threshold >46.55°C
	OR (IF	42.5 mm VAS<CO2 intensity ≤50.25 mm VAS
	AND)	Pressure pain threshold >27.25 N/m2
Cluster #2:	IF	CO2 intensity >50.25 mm VAS
	AND	Pressure pain threshold >27.25 N/m2
Cluster #3:	IF	CO2 intensity >42. 5 mm VAS
	AND	Pressure pain threshold ≤27.25 N/m2
Cluster #4:	IF	CO2 intensity ≤42. 5 mm VAS
	AND	Heat threshold ≤46.55°C

The CART identifiers of the cluster membership correctly assigned 95.1% of the subjects.