The validity of the neuropathic pain scale for assessing diabetic neuropathic pain in a clinical trial.
OBJECTIVE
In controlled trials of analgesics for the treatment of neuropathic pain, the primary outcome variable is most often a measure of global pain intensity. However, because neuropathic pain is associated with a variety of pain sensations, the effects of analgesic treatments on different sensations could go undetected if specific pain qualities are not assessed. This study sought to evaluate the utility of assessing the multiple components of neuropathic pain in an analgesic clinical trial.


METHODS
One hundred fifty-nine subjects with diabetes-related foot pain were randomly assigned to receive an active analgesic (controlled-release oxycodone) or matching placebo for 6 weeks. A multidimensional measure of neuropathic pain, the Neuropathic Pain Scale (NPS), was administered before, during, and after study treatment.


RESULTS
Relative to placebo, the opioid analgesic produced statistically significantly greater decreases in global pain intensity, pain unpleasantness, and sharp, dull, and deep pain sensations. Responder analyses indicated a higher rate of responding to the opioid condition, relative to placebo, for intense, unpleasant, deep, and surface pain. The opioid analgesic did not significantly reduce hot, cold, itchy, or sensitive pain sensations compared with placebo in either analysis.


CONCLUSIONS
These findings support the utility of the NPS for characterizing the multidimensional nature of the neuropathic pain experience and for detecting changes in neuropathic pain with treatment.
Jensen
Mark P
MP
Department of Rehabilitation Medicine, University of Washington School of Medicine and Multidisciplinary Pain Center, Seattle, WA 98195-6490, USA. mjensen@u.washington.edu
Friedman
Michael
M
Bonzo
Daniel
D
Richards
Patricia
P
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000704:Analysis of Variance; D016022:Case-Control Studies; D003929:Diabetic Neuropathies / Q000188:drug therapy* / Q000523:psychology; D004311:Double-Blind Method; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009294:Narcotics / Q000627:therapeutic use*; D010098:Oxycodone / Q000627:therapeutic use*; D010147:Pain Measurement; D017288:Pain Threshold / Q000187:drug effects; D015203:Reproducibility of Results; D016896:Treatment Outcome
D009294:Narcotics; D010098:Oxycodone