An ecological study of the extent and factors associated with the use of prescription and over-the-counter codeine in Australia

Natasa Gisev, Suzanne Nielsen, Elena Cama, Briony Larance, Raimondo Bruno, Louisa Degenhardt

The extent and factors associated with codeine use in the community remain poorly understood despite the widespread global use of codeine. The aim of this study was to examine the use of prescription and over-the-counter (OTC) codeine in Australia and identify the geographic and socio-demographic characteristics associated with prescription and OTC codeine use. National sales data for prescription and OTC codeine (supplied by IMS Health) were used to estimate codeine utilisation (in pack sales and milligrammes) in Australia during 2013, mapped to Australian Bureau of Statistics (ABS) Statistical Local Areas (SLAs) and Remoteness Areas. Socio-demographic characteristics and total population estimates of SLAs were obtained from the ABS. SLA-level data on sex, age distribution, income, occupations involving physical labour and number of pharmacies were included in linear regression analyses to examine their association with total, prescription and OTC codeine use. In total, 27,780,234 packs of codeine were sold in Australia during 2013, equating to 12,376 kg. OTC codeine preparations accounted for 15,490,207 packs (55.8 %) or 4967.30 kg (40.1 %). Nationally, an estimated 1.24 packs (or 554.10 mg) of codeine were sold per person; utilisation was higher in more remote areas. SLAs with a higher percentage of low-income earning households had the highest rates of prescription codeine use (β 0.16, p < 0.001), whereas SLAs with a higher percentage of males had the highest rates of OTC codeine use (β 0.22, p < 0.001). Codeine use is common in Australia, with clear distinctions in the geographic and socio-demographic characteristics associated with prescription and OTC codeine use.