Investigation of an opioid response categorization in advanced cancer patients

The aim of this study was to investigate a possible distinction in three ca tegories of opioid response and to identify possible facto rs associated wi th a poor response. A prospective survey was carried out in 105 consecutive patients requiring morphine for at least 4 weeks before death. Mean pain i ntensity, opioid doses and symptom intensity at weekly intervals, pain synd romes, and the presence of psychological distress were assessed. Opioid esc alation index (OEI%) was calculated from the parameters recorded. Three cat egories were considered, including (1) patients with slow increments of opi oid dose and a mean analgesic 10-cm visual analogue scale (VAS) less than 4 (responders), (2) patients with an OEI% more than 5 but a mean VAS less th an 4 (partial responders), and (3) patients with a mean VAS more than 4 (po or responders). Treating physicians were asked to make a judgment on the pa in treatment difficulties on a numerical scale (0-10). Significant differen ces in opioid starting dose (OSD), opioid dose at -4 weeks, nausea and vomi ting at -1 week, opioid maximum doses, mean VAS, and OEI were found in the three categories of response. Significant correlations with the physician j udgment were found for opioid maximum dose mean VAS, VAS at the different t ime intervals, the doses used at the different intervals, OEI, and confusio n. Neuropathic pain was significantly associated with a judgment of poor pa in outcome. The correlation between the physician judgment and the categori es of opioid response was highly significant. Seven of the 12 patients in t he third category (poor response) were considered as having a relevant psyc hological distress. The categorization of the opioid response used in this study could be used in clinical research and as an audit tool, and could be tested in other settings to compare different treatments. J Pain Symptom M anage 1999; 18:347-352. (C) U.S. Cancer Pain Relief Committee, 1999.