Objective: To model pain intensity and consequent disability by independent physical, psychological, and social variables in a group of patients with chronic upper limb pain.
Methods: We studied a group of 73 hospital outpatients with either chronic work related diffuse upper limb pain or carpal tunnel syndrome. We assessed pain intensity, disability, and personality by self-rated questionnaires; and psychiatric morbidity by a standardized interview. We measured illness behavior by assessing coping strategies, illness beliefs, financial benefits, and movements of the most affected limb.
Results: In both pain conditions, disability was positively correlated with present pain intensity, depression, helpless coping style, and receipt of state financial benefits; and was negatively correlated with age. This explained 43% of the variance and correctly classified 85% of all patients. Present pain intensity was positively correlated with both depression and the number of arm movements at night. This model explained 15% of the variance and correctly classified 75% of all patients. Inclusion of diagnostic group has no effect on these models.
Conclusion: The correlations between disability and pain intensity with both psychosocial and physical factors support the biopsychosocial model of disability in particular, and pain to a lesser extent, irrespective of the diagnosis.