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[Three of the authors respond:]
We thank Tushar Mehta for his comments regarding clinical trials to assess the efficacy of opioids for noncancer pain. Retrospective studies are indeed subject to recall bias, but we used only prospective controlled clinical trials in our meta-analysis.1 We extracted 2 outcome measures for our analyses: present pain intensity and present functional status. We avoided using outcomes measured as “better, the same or worse” because they are subject to recall bias. We were also careful to analyze the included studies with regard to valid outcome measures. The studies included in this review were judged to have valid outcome measures.
Mehta expresses doubts about the ability of a patient who is receiving opioids to validly report pain relief, but many studies have now established the validity of measures of pain relief as well as measures of functional status. Both of these types of outcome measures must be included if a trial is to be clinically relevant, and a valid prospective study must include comparisons of measurements taken at baseline and at subsequent points during treatment and follow-up in order to assess a therapy's efficacy.
In cases of substance abuse, opioids can be euphorigenic and continued use can lead to tolerance and even intermittent withdrawal symptoms. Our experience in pain relief clinics is that the great majority of people requiring opioids for pain relief are not addicted. Although it is normal for people to develop tolerance to opioids, nonaddicted patients with chronic noncancer pain do not commonly experience withdrawal phenomena if opioids are prescribed appropriately, and if sustained-release preparations are used.
REFERENCE
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