(230) StEPS: a novel tool to phenotype and rate the severity of painful polyneuropathy

Abstract

Patients with peripheral neuropathic pain typically present with a combination of pain and somatosensory deficits. Pain may occur spontaneously or manifest as increased sensitivity to external stimuli (allodynia, hyperalgesia). These symptoms and signs often vary between patients, indicating differences in the pathophysiological mechanisms responsible for nerve damage, loss of sensory function or pain that are likely to have therapeutic relevance. We investigated the variance in symptoms and signs associated with diabetic polyneuropathy (DPN). DPN is a major cause of neuropathic pain and a frequent target condition in analgesic treatment trials. Our aim was to develop a tool for the assessment of painful peripheral neuropathies such as DPN that captures differences and commonalities of clinical phenotypes in a simple standardized bedside evaluation. The study included 25 patients with type 2 diabetes (DM2) but no clinical evidence of DPN, 61 patients with DPN and chronic neuropathic pain, 19 patients with painless DPN and 20 healthy subjects. Study participants completed a structured interview (47 items) and a standardized physical examination (39 items). We determined principal components of the phenotypic variance by analyzing the temporal characteristics, stimulus-dependence and sensory character of pain, the presence of paresthesia, clinical signs of autonomic nervous system involvement, and the outcome of physical tests of sensory function. Correlation patterns of symptoms and signs were examined for features discriminating between DPN phenotypes. We combined interview questions and physical tests identifying these features in an abridged assessment tool that we named Standardized Evaluation of Pain and Somatosensory Function (StEPS). StEPS generates a phenotypic profile of painful neuropathy without requiring quantitative sensory testing. The profile includes separate intensity ratings of spontaneous or evoked pain to allow recording the response to analgesic treatment with greater specificity than conventional global pain scores. Supported by an unrestricted research grant from GlaxoSmithKline.