Background: In addition to its antidiabetic effects, metformin has pleiotropic effects, such as the inhibition of carcinogenesis. This study aimed to investigate the association between metformin use and pancreatic cancer risk in the Korean National Health Insurance Service (NHIS)-National Health Screening Cohort (HEALS).Methods: Of the individuals in the Korean NHIS-HEALS, 29,271 men and 19,091 women were included in the final analysis after propensity score matching based on age, body mass index, and smoking status. The study population was categorized into three groups: metformin non-users with diabetes mellitus (DM), metformin users with DM, and non-diabetic users. A Cox proportional hazards regression model was used to examine the association between metformin use and pancreatic cancer.Results: The median follow-up period was 12.9 years. The estimated pancreatic cancer incidence was highest in metformin users with DM, regardless of sex (P<0.001), and lowest in non-diabetic men and female metformin non-users (P=0.053). The hazard ratios (95% confidence interval) for pancreatic cancer incidence in metformin users and non-diabetic individuals were 1.116 (0.648–1.923) and 0.447 (0.259–0.771) in men and 2.769 (1.003–7.642) and 1.451 (0.529–3.984) in women, respectively, after full adjustment.Conclusion: Women with diabetes using metformin are at a higher risk of pancreatic cancer than women with diabetes not using metformin. Meanwhile, men with DM using metformin have a similar risk of pancreatic cancer as men with DM not using metformin.

OBJECTIVES: Opioids are prescribed to treat moderate to severe pain. We investigated recent trends in opioid (morphine, oxycodone, fentanyl, and hydromorphone) prescriptions using data from the Korean National Health Insurance Service-National Sample Cohort between 2002 and 2015.METHODS: The morphine milligram equivalent (MME) was calculated to standardize the relative potency of opioids. The number (cases) or amount (MME) of annual opioid prescriptions per 10,000 registrants was computed to analyze trends in opioid prescriptions after age standardization. Joinpoint regression analysis was conducted to calculate the annual percentage change and average annual percentage change (AAPC).RESULTS: The number (cases) of prescriptions per 10,000 registrants increased from 0.07 in 2002 to 41.23 in 2015 (AAPC, 76.0%; 95% confidence interval [CI], 61.6 to 91.7). The MME per 10,000 registrants increased from 15.06 in 2002 to 40,727.80 in 2015 (AAPC, 103.0%; 95% CI, 78.2 to 131.3). The highest AAPC of prescriptions and MME per 10,000 registrants were observed in the elderly (60-69 years) and in patients treated at general hospitals. Fentanyl prescriptions increased most rapidly among the 4 opioids.CONCLUSIONS: Consumption of opioids greatly increased in Korea over the 14-year study period.