Potentially Inappropriate Use of Transdermal Fentanyl in Working-Age and Older Adult Populations with Non-Cancer Pain: Nationwide Cross-Sectional Study.

Background: As a potent opioid analgesic, fentanyl transdermal patches (FTDs) have been widely used in patients with moderate to severe pain. However, increasing concerns about the opioid epidemic have made it important to strengthen the rational use and management of FTDs. Objective: Our objective was to investigate the trends in the use of FTD and to evaluate potentially inappropriate FTD use in patients with noncancer pain, based on established evaluation criteria, referring various recommendations and guidelines. Methods: A nationwide cross-sectional study was conducted using a national insurance claims database from 2014 to 2020. The study included patients who were prescribed FTDs at least once a year in an outpatient setting, while excluding cancer or pediatric patients. To identify potentially inappropriate use, we developed evaluation criteria based on the established recommendations for the safe use of prescription opioids in patients with noncancer pain and assessed each patient's compliance. The working-age and older adult groups were compared to evaluate the differences in FTD use, and modified Lorenz curves and Gini coefficients were used to assess the equality of FTD use. Results: A total of 5386 patients and their 19,800 reimbursements were included in the study. The number of patients with FTDs decreased from 58.6 to 53.7 per 100,000 registrants between 2014 and 2020. Meanwhile, the number of reimbursements increased by 7.4%, from 203.2 to 218.1 per 100,000 registrants during the same period. The working-age patients had an average of 3.9 reimbursements per year, with an average morphine milligram equivalent per day (MME/day) of 64.4 for each reimbursement. The older adult patients had an average of 3.5 reimbursements per year, and their average MME/day was 47.9. As a result of applying the evaluation criteria, 567 (24.5%) working-age patients and 531 (17.3%) older adult patients were identified as potentially inappropriate FTD users. Among patients with multiple FTD prescriptions, the working-age group with potentially inappropriate FTD use had significantly higher estimated MME/day than the older adult group (P<.001). The modified Lorenz curve showed that more than 70% of the total FTDs used in the working-age group were consumed by those with potentially inappropriate FTD use, while older adult group with potentially inappropriate FTD use accounted for less than 50% of the total older adult patients. The working-age patients also had a higher Gini coefficient than the older adult group, indicating unequal use of FTDs (0.461 vs 0.406). Conclusions: Although the number of patients receiving FTD prescriptions has decreased during the study period, the total amount of FTDs consumed increased, suggesting that caution is warranted. This study also highlights the potential for inappropriate FTD use in working-age patients. Further research is needed to quantify and qualify the risk factors in patients with potentially inappropriate use, given the clinical rationale associated with prescribing FTDs.