Relationships among pain disability, pain intensity, illness intrusiveness, and upper extremity disability in patients with traumatic peripheral nerve injury

Purpose In patients with a peripheral nerve injury, a simple conceptualization assumes that pain disability is determined by pain intensity. This study evaluated the relationships among pain intensity, illness intrusiveness, and pain disability. Methods After we obtained ethics board approval, we enrolled English-speaking adult patients who had experienced an upper extremity peripheral nerve injury 0.5 to 15 years previously. Patients completed the Disabilities of the Arm, Shoulder, and Hand (DASH), Illness Intrusiveness Scale, Pain Disability Index, and McGill Pain questionnaires. We used multivariate linear regression to evaluate the variables that predicted pain disability. Results There were 124 patients (41 women, 83 men; mean ± SD, 41 ± 16 y of age). The median time since injury was 14 months (range, 6145 months), and there were 43 brachial plexus nerve injuries. Mean ± SD scores were: pain disability, 29 ± 18; illness intrusiveness, 40 ± 18; DASH, 45 ± 22; and pain intensity, 4.6 ± 3.0. The pain disability, DASH, and illness intrusiveness scores were significantly higher in patients with brachial plexus injuries than in those with distal nerve injuries (p<.05). There was strong correlation between pain disability and DASH (r = 0.764, p<.001) and illness intrusiveness (r = 0.738, p<.001) and a weaker correlation with pain intensity (r = 0.549, p<.001). The final regression model predicting pain disability scores explained 70% of the variance with these predictors: DASH (β = 0.452, p<.001), illness intrusiveness (β = 0.372, p<.001), and pain intensity (β = 0.143, p=.018). Conclusions Pain disability was substantial after nerve injury, and pain intensity explained the least variance among the model variables. Pain intensity should be considered only one component of pain, and the impact of pain in the context of disability should be considered in patients with chronic nerve injury. Type of study/level of evidence Prognostic IV.