An exploratory study of factors associated with long-term, high-dose opioid prescription in cancer patients in Japan based on a medical claims database

Purpose As the cancer survivors increase, patients using long-term and high-dose opioids are also increasing. Therefore, the promotion of appropriate use is important. This study investigated the actual status of opioid prescriptions in Japan and identified factors associated with long-term, high-dose prescription. Methods We conducted a case-control study using a hospital-based administrative claims database. Patients with a diagnosis of cancer and prescriptions of opioids were included. Patients who received continuous opioid for less than 183 days were defined as the “control,” and patients who received continuous opioid at higher dose levels (≥ 120 mg/day of oral morphine equivalent) for 183 days or more were defined as the “case.” The case was subdivided into two groups: those with the duration of less than 730 days (case I) and 730 days or more (case II). After describing factors possibly associated with long-term, high-dose opioid prescription, ordinal logistic regression analysis was conducted. Results We included 19,176 patients; of these, 13,517 were in the control, 111 were in the case I, and 682 were in the case II. The analysis showed that distant metastasis, back pain, dose of opioids, non-opioid analgesics, prescription, and chemotherapy during the opioid prescriptions were significantly associated with long-term, high-dose opioid prescription. Conclusion Four percent of the study population were prescribed long-term, high-dose opioids, and several comorbidities and concomitant medications were identified as associated factors. Opioids might be also prescribed for non-cancer chronic pain. It is necessary to properly distinguish the type of pain and to use opioids safely and appropriately.