Exploration of the evidence.

Faced with rapidly escalating costs, healthcare policy makers are increasingly turning to research evidence to serve as a basis for their population-based decisions on access and funding of new and existing therapies-health technology assessment. A two-stage approach is often used to arrive at a policy recommendation for a given treatment. First, following a systematic review of literature, the "level of evidence" for the treatment is assessed according to epidemiological principles. Then a grade of policy recommendation is provided based on both the level of evidence and the applicability of the evidence to current clinical practice. To assess the current evidence basis for refractory neuropathic pain, a comprehensive search was undertaken for systematic reviews of pharmacological interventions and interventional procedures (ie, spinal cord stimulation, therapeutic blocks, radiofrequency procedures, and surgery). Of the 33 systematic reviews identified, the majority provided evidence for the use of drugs and spinal cord stimulation in the management of various neuropathic pain indications. Little evidence was found for either radiofrequency procedures or therapeutic blocks. By including randomized controlled trials, a number of these systematic reviews indicate a high grade of evidence. Nevertheless, more pragmatic clinical trials are needed to address the evidence needs of healthcare policy makers. These trials should address a direct comparison of the relative effectiveness of neuropathic pain therapies, particularly in combination with other therapies and at different points in the disease course.