Divergent Analgesic Prescribing Trends in Taiwan, 2001–2020: An Age–Period–Cohort Analysis of Opioid, NSAIDs, and Paracetamol Prescribing (Preprint)

BACKGROUND Despite ongoing global changes in analgesic prescribing practices, long-term trends accounting for age, period, and cohort effects remain poorly understood in Asian populations, where opioid and non-opioid prescribing trajectories differ from those observed in Western nations. OBJECTIVE To examine the long-term prescribing trends of opioids, NSAIDs, and paracetamol in Taiwan by age, calendar period, and birth cohort using an APC framework. METHODS We conducted a population-based, repeated cross-sectional study using Taiwan National Health Insurance claims data (2001–2020). The cohort included all insured individuals aged 1–85 years, with an annual population size of 22.3–23.1 million. Exposure variables were structured for age-period-cohort modeling, comprising 5-year age groups, four 5-year calendar periods (2001–2020), and 5-year birth cohorts (1920–1924 to 2015–2019). RESULTS Opioid prescribing prevalence escalated from 123.7 per 100,000 persons in 2001–2005 to 706.9 in 2016–2020. APC analysis showed a significant positive net drift for opioids (+10.93% per year; 95% CI, 10.36%-11.51%). In contrast, paracetamol and NSAIDs showed overall declines (net drifts: -2.44% [95% CI, -2.58% to -2.29%] and -0.82% [95% CI, -0.97% to -0.66%], respectively). Notably, local drifts revealed a significant increase in NSAID prescribing only among adolescents aged 11–15 years (+0.80% per year; 95% CI, 0.34%-1.27%). Generational analysis suggested higher opioid prescribing risk among younger cohorts (RRs = 3.06 for the 2015–2019 cohort), although the increase relative to the 2000–2004 reference cohort was not statistically significant. CONCLUSIONS Analgesic prescribing in Taiwan has diverged, with a consistent increase in opioids across all ages and a shift toward NSAID use in younger populations. These observed trends inform targeted pharmacovigilance and policies to ensure appropriate pain management while mitigating potential opioid-related risks.