Comparison of continuous subcutaneous hydromorphone hydrochloride and morphine hydrochloride injection on skin disorders incidence: a retrospective study

Background: Continuous subcutaneous administration of injectable opioids is simple and effective; however, skin disorders may occur when high opioid dosages are used. Therefore, we investigated opioid injection drugs with a low risk of skin disorders.

Methods: A retrospective study was conducted using the electronic medical records of patients prescribed 1% hydromorphone hydrochloride or 4% morphine hydrochloride with instructions for continuous subcutaneous administration at Shizuoka Cancer Center from January 2017 to December 2021. The primary endpoint was skin disorders incidence, and the two groups were compared using Cox proportional hazards model analyses and Fisher's exact test at 5% significance level. Patient background factors expected to influence skin disorders were also investigated, and multivariate logistic analysis of skin disorders incidence was performed.

Results: The incidence of skin disorders in the hydromorphone hydrochloride and morphine hydrochloride groups were 3.7% (1/27 patients) and 28.1% (9/32 patients), respectively, showing a significant difference in two statistical analyses between the two groups (Cox proportional hazards model analyses HR: 0.09, 95% CI: 0.01-0.70, P = 0.022. Fisher's exact test OR: 0.10, 95% CI: 0.01-0.84, P = 0.016). In the multivariate analysis, the administration of hydromorphone hydrochloride (OR: 0.04, 95% CI: 0.003-0.48, P = 0.012) was also found to have a significant negative correlation with the occurrence of skin disorders. On the contrary, administration period ≥ 28 days (OR: 18.16, 95% CI: 2.22-148.60, P = 0.007) was a factor with a significant positive correlation.

Conclusions: Subcutaneous 1% hydromorphone hydrochloride administration had a lower risk of skin disorders than 4% morphine hydrochloride injection. Moreover, prolonging the administration period increased the risk of developing skin disorders. This suggests that a 1% hydromorphone hydrochloride Injection is a good clinical decision for patients who are likely to have a longer administration period and require a higher dosage of injectable opioids.

Trial registration: Retrospectively registered.