Trends in licit opioid use in Australia, 1984-1998: comparative analysis of international and jurisdictional data

To examine trends from 1984 to 1998 in licit opioids used in Australia compared with nine other developed countries, and in New South Wales compared with other Australian jurisdictions.

Poisson regression analysis of annual rates of national and jurisdictional consumption of methadone, morphine and pethidine.

All drug data were standardised to defined daily doses per 1000 population per day.

Methadone consumption increased by, on average, 12% per year (RR, 1.12; 95% CI, 1.08-1.17), with Australia in the first rank of countries. Morphine use increased by 5% per year (RR, 1.05; 95% CI, 1.02-1.09), with Australia ranking equal second with three other countries behind Denmark. Consumption of pethidine in all 10 countries was unchanged (RR, 0.99; 95% CI, 0.97-1.00), with Australia equal first. In Australia, use of methadone syrup increased by 17% per year (RR, 1.17; 95% CI, 1.16-1.17) and by 11% per year for methadone tablets (RR, 1.11; 95% CI, 1.10-1.12). Consumption of methadone syrup in NSW was more than double that of any other jurisdiction. Consumption of methadone tablets was 2.4 times higher in South Australia (RR, 2.35; 95% CI, 2.09-2.65) than NSW. The Northern Territory, Tasmania and Queensland also had significantly higher consumption than NSW. From 1991 to 1998, controlled-release morphine consumption increased by 27% per year nationally (RR, 1.27; 95% CI, 1.24-1.30). The NT had 2.6 times more supply of morphine (RR, 2.63; 95% CI, 1.71-4.03) and Tasmania 58% more supply than NSW (RR, 1.58; 95% CI, 1.11-2.25).

Australia's consumption of licit opioids ranked high internationally. There were diverse trends in the supply of licit opioids to Australia's jurisdictions, resulting in a heterogeneous pattern throughout the country.