TITLE:
Sub-Grouping Healthy Subjects’ Sensitivity to Pain and Its Relationship to Personality Traits: Results of a Cluster Analysis
AUTHORS:
Dorit Pud, Roi Treister, Elon Eisenberg
KEYWORDS:
Cluster Analysis, Cold Pressor Test, Experimental Pain, Human, Personality Traits
JOURNAL NAME:
Applied Mathematics,
Vol.5 No.11,
June
20,
2014
ABSTRACT: Objective: Individual differences in the sensitivity
to pain and the factors that may contribute to these differences are well
studied. Nevertheless, there is no single test that can reliably classify
subjects as being sensitive or insensitive to pain. Methods: In the present study, hierarchical clustering and
K-means cluster analysis was used to identify subgroups among 191 healthy
subjects (105 females, 86 males) according to their sensitivity to pain. Group
determination was based on the subjects’ response to experimental noxious stimuli
of heat (pain intensity), cold (cold pain threshold, tolerance, and intensity),
and conditioned pain modulation (CPM, tested by co-administering repeated short
painful heat stimuli and a conditioning tonic cold pain stimulation). In addition,
in order to determine if the subjects in these subgroups differed on
personality traits scores on Cloninger’s Tridimensional Personality
Questionnaire (TPQ, outcome
measure) for the three dimensions of personality: Novelty Seeking (NS); Harm
Avoidance (HA); and Reward Dependence (RD) were calculated. Results: Based on pain scores,
subjects were grouped as low pain (57%) with a low level of sensitivity in pain
parameters, or high pain (43%) cluster members. The high pain had significant
higher scores of HA (p = 0.05) and RD (p = 0.05) than the low pain group. Conclusions: This method of
sub-grouping may be useful for identifying the mechanisms underlying individual
variability in the sensitivity to pain and may point to groups at risk for experiencing
high levels of clinical pain.