A Cochrane review [Abstract] 1 included 8 studies with a total of 1 283 adults with cancer pain (1 181 participants available for analysis). Four studies compared hydromorphone to oxycodone, 3 compared hydromorphone to morphine, and 1 study compared hydromorphone to fentanyl. Overall, there was no evident difference in treatment efficacy between groups, and the mean postintervention pain scores were generally below the threshold for 'no worse than mild pain' on all investigated treatments.
Hydromorphone compared with oxycodone:There was no difference in pain intensity (measured using a visual analogue scale, VAS; 3 studies, n=381).There was no clear difference in nausea (RR 1.13 95% CI 0.74 to 1.73; 3 studies, n=622), vomiting (RR 1.18, 95% CI 0.72 to 1.94; 3 studies, n= 622), dizziness (RR 0.91, 95% CI 0.58 to 1.44; 2 studies, n=441) and constipation (RR 0.92, 95% CI 0.72 to 1.19; 3 studies, n=622) between hydromorphone and oxycodone.Hydromorphone compared with morphine:There was no difference in pain intensity (measured using the Brief Pain Inventory, BPI or VAS; 2 studies, n=433).No difference in the number of clinically improved participants, defined by 50% or greater pain relief rate, in the hydromorphone group compared with the morphine group was observed (RR 0.99, 95% CI 0.84 to 1.18; 1 study, n=233).At 24 days of treatment, morphine reduced constipation compared with hydromorphone (RR 1.56, 95% CI 1.12 to 2.17; 1 study, n=200). No difference in nausea (RR 0.94, 95% CI 0.66 to 1.30; 1 study, n=200), vomiting (RR 0.87, 95% CI 0.58 to 1.31; 1 study, n=200) and dizziness (RR 1.15, 95% CI 0.71 to 1.88; 1 study, n=200) were observed between hydromorphone and morphine. Hydromorphone compared with fentanyl:There was no difference in pain intensity (measured by numerical rating scale, NRS) at 60 minutes between hydromorphone and fentanyl (1 study, n=82).
Comment: The quality of evidence is downgraded by study limitations (incomplete outcome data, high loss to follow-up), by imprecise results (few patients), and by suspected publication bias (only small and mostly commercially funded studies).
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