Illness behavior and psychosocial factors in diffuse upper limb pain disorder: a case-control study.

Objective: To compare behavioral and other psychosocial factors in patients with diffuse upper limb pain disorder (ULPD) and patients with carpal tunnel syndrome (CTS).

Methods: We compared 37 hospital outpatients with diffuse ULPD with 36 hospital outpatients with CTS, matched by sex, pain intensity, and duration of illness. We assessed psychiatric morbidity by a standardized interview, and both symptoms and personality by self-rated questionnaires. We measured illness behavior by assessing financial benefits and compensation, coping strategies, illness beliefs, treatments received, and 24 hours of monitoring movements of the most affected arm and the body as a whole.

Results: There were no significant differences in the prevalence of either current or premorbid psychiatric disorders, personality scores, symptom amplification, disability, or treatments received. Subjects with ULPD had significantly lower self-rated scores for depression, somatic distress, sleep disturbance, and physical fatigue than subjects with CTS, although there were more than normal levels of anxiety, fatigue, and sleep disturbance in both groups. There were no significant differences in the numbers of arm or body movements by day and night. Significantly more ULPD subjects had been involved in litigation, but litigating patients were a minority.

Conclusion: The primary etiology of endemic diffuse ULPD, presenting in secondary care, is no more psychiatric, psychological, behavioral, or related to personality than is the case with a similarly chronic and painful condition of known pathology. We cannot exclude either a specific role for psychosocial factors at work, or a more general role for psychosocial factors in maintaining disability in patients with chronic pain.