Objectives: The primary objective of the current study was to identify and characterize distinct chronic pain subgroups based on their level of two specific dispositional factors: experiential avoidance (EA) and anxiety sensitivity (AS). The secondary objective was to compare the subgroups in terms of substance misuse, mood, disability, and quality of life.
Design: Participants with chronic pain were assessed for demographic, psychosocial, and personality measures. A two-step cluster analysis was conducted in order to identify distinct subgroups of patients based on their level of EA and AS. Differences in clinical outcomes were compared using a MANCOVA based on cluster membership controlling from average pain intensity and time since injury. Clustering measures included: Acceptance and Action Questionnaire (AAQ) and Anxiety Sensitivity Index (ASI). Outcome measures included: CAGE substance use screening tool, Patient Health Questionnaire-9 (PHQ-9), Generalized Anxiety Disorder 7 item (GAD-7); Pain Disability Index (PDI), Pain Disability Index (PDI), Euro Quality of life (EQ5D).
Results: From a total of 204 participants, three clusters were formed. Levels of EA were highest among those in Cluster 2 (N=50), lowest among those in Cluster 3 (N=71), and moderate among those in Cluster 1 (N=83). Individuals in Cluster 2 had significantly greater substance misuse concerns than those in Cluster 3 ( p =.027). Those in Cluster 2 also had greater impairments in PHQ-9 ( p < .001), GAD-7 ( p < .001), and EQ5D ( p < .03) compared to both Cluster 1 and 3 participants. Significant difference in level of PDI was seen between Cluster 2 and Cluster 3 ( p < .001) but not Cluster 1 ( p =.18).
Conclusions: Identification and early intervention of individuals with high levels of EA and AS may potentially reduce long term disability. Increased access to multidisciplinary services may be warranted among this high risk subgroup.
Swati Mehta– Scientist, Parkwood Institute Research, Parkwood Institute
Amanda McIntyre– Research Associate, Parkwood Institute Research, Parkwood Institute
Shannon Janzen– Research Associate, Parkwood Institute Research, Parkwood Institute
Sarah Caughlin– Research Coordinator, Lawson Health Research Institute
Eldon Loh– Physiatrist, St. Joseph's Health Care London
Robert Teasell– Physiatrist, Parkwood Institute Research, Parkwood Institute