George SZ, Wallace MR, Wright TW, et al : Evidence for a biopsychosocial influence on shoulder pain: Pain catastrophizing catechol-O-methyltransferase (COMT) diplotype predict clinical pain ratings. Pain 2008;136(1-2):53-61
- The experience fo muscloskeletal pain varies considerably among individuals.
- The influence of psychological factors on pain perception and the development of chronic musculoskeletal pain has been previously reported.
- Recent studies have suggested that genetic factors also influence pain perception.
- Candidate pain genes have been identified and one gene with a high priority score is the catechol-O-methyltransferase (COMT) gene.
- One of the functions is metabolizing catecholamines involved in pain modulation both directly and indirectly, via effects on endogenous μ-opioid function.
- It has been suggested that polymorphorism resulting in reduced COMT enzyme production lead to chronic over-activity of the μ-opioid system, decreasing the ability to modulate nociceptive input.
- Our purpose was to investigate whether psychological variables specific to fear-avoidance models and COMT gene genotype influence clinical pain ratings for a cohort of patients receiving operative treatment of shoulder pain.
- self-report questionnaires
- Fear of Pain Questionnaire, Tampa Scale of Kinesiophobia, Pain Catastrophizing Scale, State-Trait Anxiety Index (STAI)
- Results
- Only pain catastrophizing made a unique contribution to pre-operative clinical pain ratings.
- In the final model, sex, pain catastrophizing, and the pain catastrophizing x COMT diplotype interaction term were the only unique contributors to pre-operative clinical pain rating.
- As with the pre-operative interactions, subject with high PCS scores and low COMT activity had significantly higher post-operative pain ratings, in comparison to the high PCS and high COMT activity pain ratings the low PCS Had low and high COMT activity pain ratings, or the low PCS and high COMT activity pain ratings.
- Discussion
- This current study considered the role that psychological and genetic factors play in the development of chronic post-operative shoulder pain.
- Pain catastrophizing is considered a maladaptive cognitive coping style comprised of magnification, rumination, and helplessness components.
- Indeed, patients with high PCS scores and low COMT activity had significantly higher pre- and post-operative clinical shoulder pain ratings when compared to the other three groups.
- At the post-operative assessment, patients with high baseline PCS scores and low COMT activity were 6.8 times more likely to have pain ratings of 4.0/10 or greater, in comparison to other groups.
- Our results suggest that high pain catastrophizing and a low COMT activity were associated with higher pre-operative pain ratings, and an increased chance of experiencing persistent pain following arthroscopic shoulder surgery.
- if predictive models involving psychological and genetic factors are validated, screening for development of chronic pain may be enhanced, resulting in early application of preventive treatment strategies.
