Socio-economic differentials in cannabis use trends in Australia

Aim To test if the degree of change in cannabis use between 2001 and 2013 differed according to socio-economic status. Design Repeated cross-sectional household surveys that were nationally representative. Setting Australia. Participants Adult samples from the 2001 and 2013 National Drug Strategy Household Surveys (n = 23642 in 2001 and n = 21353 in 2013), the largest nationally representative survey on drug use in Australia. Measurements Frequency of cannabis use coded as daily use, weekly use, less than weekly use and non-current use; socio-economic status (SES) as measured by personal income and educational level. Finding There were significant differences in changes to levels of cannabis use between SES groups. Among participants who completed high school, the probability of daily use decreased from 0.014 to 0.009 (P < 0.001), and the probability of weekly use decreased from 0.025 to 0.017 (P < 0.001). These probabilities remained stable for participants who did not complete high school. The probability of weekly cannabis use decreased from 0.032 to 0.023 among participants with middle level income (P = 0.004), and from 0.021 to 0.013 among those with high income (P = 0.005). There were no significant changes in these probabilities among those with low income (0.026 in 2001 and 0.032 in 2013; P = 0.203). Conclusion The decline in cannabis use in Australia from 2001 to 2013 occurred largely among higher socio-economic status groups. For people with lower income and/or lower education, rates of frequent cannabis use remained unchanged.