Pain after traumatic nerve injury: Clustering of phenotypes and clinical outcome.

A substantial proportion of patients experience persistent neuropathic pain following traumatic nerve injury. We hypothesize that treatment failures, at least in part, result from limited understanding of the heterogeneous nature of the patient population affected by posttraumatic peripheral neuropathies. In a previous study, a prediction model using 15 psychometric items identified three psychological "clusters" in patients with chronic pain. In this retrospective cohort study, we applied this model to 327 patients with posttraumatic neuropathic pain referred to a tertiary pain clinic. Patients were assigned to one of the three clusters and compared in terms of psychological profile, treatment received, and global perceived outcome. Cluster 1 (n=21, 6.4%) showed the highest psychological burden, the highest rate of daily smoking, and no employment. Cluster 2 (n=113, 34.6%) had the most favorable psychosocial profile and highest employment rate. Cluster 3 (n=193, 59.0%) showed intermediate features. The clusters differed significantly in terms of psychological profile (p=<0.001). Surgical interventions were performed in 20% (n=67) of the cases. Psychotherapy was applied most frequently in cluster 1. Identifying a patient's clinical phenotype that predicts variation in individual treatment response may offer an opportunity to further refine personalized treatment protocols for those with posttraumatic neuropathic pain.