Core outcome measures for chronic pain clinical trials: IMMPACT recommendations
The benefits of adopting these core outcome domains in clinical research on chronic pain would be augmented by the identification of optimal measures for assessing them. Such core outcome measures could be supplemented by measures specific to the situation or treatment being studied. Use of a standard set of outcome measures for chronic pain clinical trials would facilitate the process of developing research protocols, encourage development of multi-center projects in which all participating facilities agree to include these measures, provide a basis for determining the treatment outcomes that constitute clinically important differences, permit pooling of data from different studies, and provide a basis for meaningful comparisons among treatments of the clinical importance of their outcomes, particularly through systematic reviews (Jadad, 1998; Jadad and Cepeda, 2000).
IMMPACT-II was convened to develop consensus recommendations for specific measures of each of the IMMPACT core outcome domains. Although there have been recent attempts to recommend outcome measures for specific chronic pain conditions—including osteoarthritis (Bellamy et al., 1997), low back pain (Deyo et al., 1998), and neuropathic pain (Cruccu et al., 2004)—the only previous attempt to identify specific treatment outcome measures applicable to diverse chronic pain conditions was published over fifteen years ago (Williams, 1988). The objective of the present article is to present consensus recommendations for specific measures of each of the IMMPACT core outcome domains.