Differing Psychologically Derived Clusters in People With Chronic Low Back Pain are Associated With Different Multidimensional Profiles.

OBJECTIVES

To explore the existence of subgroups in a cohort with chronic low back pain (n=294) based upon data from multiple psychological questionnaires, and profile subgroups on data from multiple dimensions.

METHODS

Psychological questionnaires considered as indicator variables entered into latent class analysis included: Depression, Anxiety, Stress scales, Thought Suppression and Behavioural Endurance subscales (Avoidance Endurance questionnaire), Chronic Pain Acceptance Questionnaire (short-form), Pain Catastrophising Scale, Pain Self-Efficacy Questionnaire, and Fear-Avoidance Beliefs Questionnaire. Multidimensional profiling of derived clusters included: demographics, pain characteristics, pain responses to movement, behaviors associated with pain, body perception, pain sensitivity, and health and lifestyle factors.

RESULTS

Three clusters were derived. Cluster 1 (23.5%) was characterized by low Cognitive and Affective Questionnaire scores, with the exception of fear-avoidance beliefs. Cluster 2 (58.8%) was characterized by relatively elevated thought suppression, catastrophizing, and fear-avoidance beliefs, but lower pain self-efficacy, depression, anxiety, and stress. Cluster 3 (17.7%) had the highest scores across cognitive and affective questionnaires.Cluster 1 reported significantly lower pain intensity and bothersomeness than other clusters. Disability, stressful life events, and low back region perceptual distortion increased progressively from cluster 1 to cluster 3, whereas mindfulness progressively decreased. Clusters 2 and 3 had more people with an increase in pain following repeated forward and backward spinal bending, and more people with increasing pain following bending, than cluster 1. Cluster 3 had significantly greater lumbar pressure pain sensitivity, more undiagnosed comorbid symptoms, and more widespread pain than other clusters.

DISCUSSION

Clinical implications relating to presentations of each cluster are postulated.