- Past research has shown that exact recall methods, including the ‘Yesterday’ method (i.e., reporting on substance use the day prior to interview), minimise under-reporting.
- This measurement technique can also reveal whether particular drug forms are more dominant, and allow assessment of same-day use of substances whose interactive effect may be associated with greater risk of harm.
- The aims of this study were to explore changes in use of the following substances ‘yesterday’ in the IDRS 2006-2015 study: i) specific licit and illicit substances, ii) opioid and methamphetamine forms, and iii) opioid and other depressant use.
- Results revealed general stability over time in the proportion reporting use of cannabis, opioids, alcohol, and cocaine, with the former two being the primary substances consumed.
- This stability was also evident in regards to the relative prevalence of particular opioid forms (i.e., opioid substitution treatment, pharmaceutical opioids and heroin).
- Prevalence of methamphetamine use followed a U-shaped curve over the 2006-2010 period; further analysis revealed that increases in use were predominantly driven by same-day use of opioids and methamphetamine. Greater dominance of crystal use over other lower-purity methamphetamines forms in recent studies relative to other indicators may indicate the necessity for targeted harm reduction strategies.
- Further, around two-fifths of the sample each year reported using opioids with other depressants (i.e., alcohol and benzodiazepines), despite general consensus as to the risk of overdose with concomitant use, and general advice to clinicians and consumers to this effect.
- These findings emphasise the need for healthcare professionals and harm reduction services to educate PWID regarding high-risk consumption practices.