Phenotyping neuropathic pain patients: implications for individual therapy and clinical trials.

PURPOSE OF REVIEW: The sensory phenotype can be used as a surrogate marker of underlying mechanisms of pain generation and is assessed by tools like the Quantitative Sensory Testing, Patient Reported Outcomes or the Capsaicin Response Test. In order to establish an individualized, mechanism-based treatment of pain, it has to be demonstrated that subgroups of patients with a distinct sensory phenotype respond differently to a certain treatment. RECENT FINDINGS: Retrospective analyses of several clinical trials revealed that the presence of certain somatosensory abnormalities in the painful area was associated with a better treatment outcome. Examples will be discussed in this article, showing that somatosensory phenotyping of patients with neuropathic pain is a promising method to subgroup patients in order to predict their response to treatment. SUMMARY: The discussed trials show the importance of the development of an individualized pain therapy. Up to now, no clinical trial has prospectively used the sensory phenotype as an inclusion or stratification criterion. Academic researchers and pharmaceutical industry should be encouraged to implement this approach in future trial designs.