Did the under‐reporting of meth/amphetamine use increase in a general population survey in Australia as negative media coverage increased?

Aim: To test (1) if there was a change in self‐reported lifetime prevalence of meth/amphetamine use by birth cohort and (2) if the extent of under‐reporting of meth/amphetamine use was associated with the proportion of the population who nominated meth/amphetamine as a drug problem. Design Observational study using seven waves of repeated cross‐sectional nationally representative household surveys between 2001 and 2019. Setting: Australia. Participants: Participants were from three birth cohorts: 1951–60 (age 68–77 at the 2019 survey; n = 29 458; 55% female), 1961–1970 (age 58–67; n = 29 859; 57% female) and 1971–1980 (age 48–57; n = 28 758; 59% female). Data were weighted to align the sample to the Australian population. Measurements Past year meth/amphetamine use; under‐reporting of lifetime meth/amphetamine use in each birth cohort, year and survey stratum (operationalised as the difference between self‐reported lifetime prevalence in 2001 and that of each subsequent year); proportion of the population who nominated meth/amphetamine as a drug problem in each birth cohort, year and survey stratum. Under‐reporting was regressed on the proportion of people holding negative attitude towards meth/amphetamine. Survey year and birth cohort were adjusted for. Findings Between 2001 and 2019, the lifetime prevalence of meth/amphetamine decreased from 6.1% (95% CI = 5.3–6.9) to 1.7% (95% CI = 1.2–2.2) in the 1951–1960 birth cohort (p < 0.001), from 13.0% (95% CI = 12.0–14.1) to 4.4% (95% CI = 3.7–5.2) in the 1961–1970 birth cohort (p < 0.001) and from 21.4% (95% CI = 19.9–22.9) to 11.2% (95% CI = 10.0–12.4) in the 1971–1980 birth cohort (p < 0.001). The proportion who nominated meth/amphetamine as a 'drug problem' increased significantly in all three cohorts (all p < 0.001) and the degree of under‐reporting of meth/amphetamine use was significantly associated with proportion of people who nominated meth/amphetamine as the 'drug problem' (b = 0.09, SE = 0.01, p < 0.001). Conclusion: In Australia, the actual prevalence of lifetime meth/amphetamine use may be two‐ to fourfold higher than that estimated in the most recent national household surveys (2019). The level of under‐reporting is strongly associated with increasing negative attitudes towards methylamphetamine and d‐amphetamine use over the same period. [ABSTRACT FROM AUTHOR]