Registration for opioid agonist treatment in Ireland from 1999 to 2019: positive findings in younger individuals.

Disclosure of interest statement: This study was financed with internal funds. No external sponsor played a role in any part of the study.  

Background: To improve understanding of problematic opioid use, monitoring patterns of consumption is essential. We investigated changes in registrations for new opioid agonist treatment (OAT) in Ireland from 1999 to 2019.

Methods: Data on individuals aged 15 to 64 years who registered for OAT in Ireland for the first time from 1999 to 2019 were retrieved from the Central Treatment List, the database of all individuals receiving OAT in Ireland. Numbers and rates of new registrations in relation to age and sex were examined.

Results: The total number of individuals with first-time treatment episodes for opioid use in Ireland decreased from 1014 in 1999, to 741 in 2019. There was a corresponding decrease in the overall incidence of new treatments from 40.7 per 100,000 to 23.0 per 100,000 (p<0.001). The downward trend, seen in both sexes, was largely accounted for by steep declines among 15 to 34 year-olds, particularly in those aged 24 years and younger, among whom there was an over 90% drop in first presentation for OAT between 1999 and 2018. In contrast, a small increased incidence was observed in new registrations for OAT among 35 to 64 year-olds.

Conclusion: The trends observed indicate an overall and sustained decline in opioid use disorder in Ireland. The particularly favourable findings among younger individuals support the view that recent drug policy in Ireland has contributed to the decline in heroin use among this group.