Reliability, Validity, and Acceptability of a Novel Visual Scale for Estimating Daily Methamphetamine Use Among People Who Use Methamphetamine

Methamphetamine is a widely used psychostimulant associated with substantial cardiovascular and neuropsychiatric morbidity. The toxic effects of methamphetamine are dose-dependent, but clinical trials of interventions for methamphetamine use disorder often rely on urine drug screening as a primary outcome. Urine drug screening provides qualitative results and can remain positive for 5-7 days after using methamphetamine, thus limiting its use in trials that seek to measure use reduction and not only abstinence as a treatment outcome.

Existing methods of measuring the frequency and amount of methamphetamine use include timeline follow-back (TLFB), which provides only days of use without any assessment of amount used each day, and hair sampling analysis, which may be able to demonstrate within-subject reduction in use over time but is impacted by numerous variables (including age, sex hormones, presence of hair, willingness to provide hair, hair color, and exposure to secondhand methamphetamine smoke) that limit its widespread use and inter-person reliability.

To address this gap in methods for measuring reductions in methamphetamine use, we developed a novel visual scale that uses measured quantities of a methamphetamine analog (crystallized phenethylamine hydrochloride) encased in transparent polyester resin blocks, similar to food intake visual scales that use three-dimensional models of food portions. The purpose of this study is to assess the reliability, validity, and acceptability of the methamphetamine analogue visual scale (MAVS) among people who use methamphetamine (PWUM) with the hope of using the scale in future trials of pharmacotherapies for methamphetamine use disorder.