Objectives: Abuse of zolpidem has sporadically been reported and little is known regarding nationwide patterns of zolpidem use in Korea. This study investigates the extent of zolpidem usage exceeding the recommended duration and the predictors.
Methods: We conducted a drug utilization study using the national sample cohort database of the Korea National Health Insurance Corporation between 2002 and 2013. The study subjects were patients treated with zolpidem in the outpatient setting. An episode was defined as a period of continuous zolpidem therapy. The provider-based episode allowed for a gap of up to 3 days between two consecutive prescriptions from the same institution. The person-based episode allowed for a gap of up to 3 days, regardless of institution. We calculated the proportion of zolpidem use for periods over 30 days and conducted logistic regression analyses to investigate the relevant predictors. An adjusted odds ratio (aOR) with a 95% confidence interval (CI) was estimated for each predictor.
Results: The usage of zolpidem is dramatically increased by approximately 18 times since zolpidem was authorized in the market (1181 in 2002 vs. 21,399 in 2013). The treatment duration in 8.3% of episodes exceeded 30 days out of 75,087 zolpidem users. The odds of zolpidem prescription exceeding 30 days were highest in patients aged 65 years and older (aOR = 2.13, 95% CI 1.78-2.53) and at tertiary hospitals (aOR = 2.14, 95% CI 1.68-2.72). Women were more likely than men to be treated with zolpidem for over 30 days.
Conclusion: We found dramatic increase of zolpidem use from 2002 to 2013. In 8.3% of the prescribed episodes of zolpidem, the recommended duration was exceeded. Efforts are required to reduce prescriptions that are inconsistent with the recommended guidelines for older patients, women, and in tertiary hospitals.
Keywords: Drug utilization; Healthcare database; Treatment duration; Zolpidem.