Population-based claims study of regional and hospital function differences in opioid prescribing for cancer patients who died in hospital in Japan.

Background: Opioids are essential for cancer pain; however, regional and hospital prescribing variations in Japan remain poorly understood. This study aimed to investigate the regional and hospital functional differences in opioid prescribing among terminally ill patients with cancer in Japan using nationwide claims data.

Methods: We analysed anonymized claims data from the DeSC database, focusing on patients who died of cancer in hospitals (2018-2022). We calculated opioid prescription prevalence and mean daily doses (converted to oral morphine equivalents) in the last 30 days of life. Outcomes were compared across regions and hospital functions using multivariate logistic and linear regression models adjusted for age, sex, and cancer type.

Results: We analysed 119 850 decedents. Oxycodone injection use was highest in Tokai (16.4%) and South Kanto (15.7%), approximately four times that in Shikoku (4.0%). Transdermal fentanyl use ranged from 51.5% in Kyushu/Okinawa to 25.4% in South Kanto. Oxycodone injections increased with hospital functionality (4.1% in non-acute care vs. 20.4% in university hospitals), whereas transdermal fentanyl use declined (56.7%-13.1%). Compared to South Kanto, adjusted odds ratios (ORs) for opioid prescribing were higher in Kyushu/Okinawa (1.29) and lower in Kinki (0.68). For dose, no region exceeded South Kanto, and the lowest geometric mean ratio (GMR) was observed in Shikoku (0.87). No significant differences in adjusted ORs or GMRs were observed across hospital categories.

Conclusion: Opioid prescribing patterns varied across regions and hospital functions, with significant differences in both prevalence and dosing. These findings may contribute to advancing the uniform implementation of palliative care.