Objective: This analysis, carried out in the context of a wider observational prospective study, tried to explore whether four World Health Organization/step-III opioids (morphine, oxycodone, fentanyl, and buprenorphine) had different effectiveness when using several different outcomes and endpoints.
Design: Cross-sectional and longitudinal design.
Setting: Oncologic, palliative, and pain centers in Italy.
Patients: Two hundred fifty-eight cancer patients monitored over a 3-week follow-up program. Intervention. Not applicable.
Outcome measures: The analgesic efficacy was assessed using effectiveness endpoints, such as pain intensity, pain intensity difference (PID), proportion of nonresponders (NR) and full-responders (FR) subjects, percentage of switches and dose escalation.
Results: Mean values of PID led to differences among opioids ranging from 10% to 30%. FR (PID ≥ 30%) were more frequent in buprenorphine-fentanyl-oxycodone groups than in morphine; NR (PID ≤ 0%) were variable. The percentage of switches resulted three times more frequent when using morphine than buprenorphine (24.4% vs 8.6%). An increase of dose ≥ 5% a day was observed in 33.3% of fentanyl patients vs 15% of buprenorphine. As a whole, opioids show some different behaviors on the basis of the considered endpoints.
Conclusions: The observed results, even if the small sample size and the nature itself of the study do not allow a definitive evaluation of the effectiveness of the drugs, underline a degree of variability among opioids and address toward a correct planning of a comparative randomized clinical trial that is now underway in Italy. For this reason, a confirmative effectiveness randomized controlled trial is required.
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