Randomized Clinical Trials of Pregabalin for Neuropathic Pain: Methods, Results, and Implications

Abstract

Key words : diabetic peripheral neuropathy, neuropathic pain, postherpetic neuralgia, pregabalin, randomized clinical trials, spinal cord injury. Introduction and Overview Neuropathic pain is caused by lesions or diseases affecting somatosensory pathways within the peripheral or central nervous system (IASP Special Interest Group on Neuropathic Pain, 2006; Merskey & Bogduk, 1994). Chronic neuropathic pain is common in clinical practice, and patients with conditions such as diabetic peripheral neuropathy (DPN), HIV sensory neuropathy, and spinal cord injury suffer from neuropathic pain that impairs their health-related quality of life, causing physical disability and emotional distress (Jensen et al ., 2007). The distinction between neuropathic pain and non-neuropathic inflammatory or musculoskeletal pain is important because it reflects at least partially distinct pathophysiologic mechanisms and somewhat different patterns of treatment efficacy. Neuropathic pain can be diagnosed based on a medical history of a nervous system lesion or disease consistent with the patient's report of pain and neurological examination findings of negative and positive sensory phenomena in the same area innervated by damaged nervous system pathways (Dworkin et al ., 2003a). Chronic neuropathic pain is more common than generally appreciated, with as many as three million patients with painful DPN (Schmader, 2002) and one million patients with postherpetic neuralgia (PHN) (Bowsher, 1999) in the United States. Until relatively recently, there were few treatments available with established efficacy for patients with chronic neuropathic pain. On the basis of results from randomized placebo-controlled trials published within the past several years (Dworkin et al ., in press; Finnerup et al ., 2005), an evidence-based treatment approach for patients with chronic neuropathic pain is now possible.