OBJECTIVES: We aimed to investigate the rate of opioid injection prescriptions in the Korean population.

METHODS: We conducted a retrospective cross-sectional study using the National Health Insurance Service-National Sample Cohort, representing a population-based for South Korea. Outpatients (18≤Y) who received one or more opioid injection prescriptions between 2008 and 2015 were selected for the study population. We investigated the opioid injection rate, which is the total number of opioid injection prescriptions per year divided by the total number of visits per year. We also presented those for subgroups according to age and institution type. The chi-square was used to test differences in opioid injection rates. The Cochran-Armitage test for trend was used to explore linear trends of the injection rates.

RESULTS: Of all injection prescriptions (n=19,315,148) in the study population from 2008 to 2015, the opioid injection prescriptions were 24.6%. The greatest proportion was observed for tramadol (97.71%), followed by meperidine (2.11%), morphine (0.12%), and fentanyl (0.06%). Opioid injection rates decreased from 9.10% in 2008 to 7.20% in 2015 (trend P<0.0001). However, the proportion of opioid injection in adjusted total injection remained consistently high from 28% to 29% and did not change significantly (trend P=1.00). The opioid injection rates decreased year by year except for those in their 20s (trend P<0.0001). Those in their 80s showed the highest rate among all age groups, followed by those in their 70s. The clinics showed the significantly highest injection rates in all periods (P<0.0001).

CONCLUSIONS: Although the opioid injection prescription rate in Korea has been decreasing from year to year, it is still maintained at a concerning level. Notably, since the opioid injection rate was shown as a high risk in the elderly and clinics, the management of those is needed.