Hospitalizations for opioid poisoning: a nation-wide population-based study in Denmark, 1998–2004

Aims   To assess hospitalization rates (HR) for poisoning with heroin, methadone or strong analgesics and relate them to quantities of prescribed methadone and strong analgesics in Denmark between 1998 and 2004.
Design   Population-based ecological study.
Settings   We extracted data on all emergency department visits and hospital admissions registered in the Danish National Patient Registry with a diagnosis of poisoning with heroin ( n  = 1688), methadone ( n  = 173) or strong analgesics ( n  = 384). To ascertain sale of prescribed medications we used data from the Danish Medicines Agency.
Measurements   Age- and gender-standardized HR and defined daily doses (DDD) per 1000 people per day.
Findings   HR for heroin poisoning was 4.4 [95% confidence interval (CI): 3.8–4.9] per 100 000 person-years (p-y) in 1998 and 4.6 (CI: 4.0–5.2) per 100 000 p-y in 2004. HR for methadone poisoning increased from 0.1 (CI: 0.0–0.2) per 100 000 p-y in 1998 to 1.1 (CI: 0.8–1.4) per 100 000 p-y in 2004. HR for poisoning with strong analgesics increased from 0.6 (CI: 0.4–0.9) per 100 000 p-y in 1998 to 2.1 (CI: 1.8–2.6) per 100 000 p-y in 2004. The sale of prescribed strong analgesics (5.0 DDD per 1000 people per day in 1998 to 5.9 DDD in 2004) and methadone (3.0 DDD per 1000 people per day in 1998 to 3.4 DDD in 2004) increased slightly between 1998 and 2004.
Conclusion   Increasing sale of prescribed methadone and strong analgesics coincided with increasing HRs of poisoning with these drugs, whereas HR of heroin poisoning varied. Further longitudinal studies are important for the guidance of future policy making.