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

Primary outcomes

1. Reliability - Timeline Follow-back

   Time frame: Conducted at enrollment (V0) and follow-up (V1) to record meth use 30 days from those dates. The data will be collected as amount per day for 30 days.

   The methamphetamine analog visual scale (MAVS) will be administered with the timeline follow-back (TLFB) at V0 and V1, which are 7-14 days apart. Each TLFB will assess 30 days prior to the date of assessment. The reliability outcome will compare within-subject reliability of meth use on overlapping days of TLFB using MAVS.

2. Validity - Hair Sample

   Time frame: Hair sample will be collected at the enrollment visit

   To assess validity, we will compare the hair sampling analysis and self-reported meth use via the MAVS/TLFB. Methamphetamine levels are determined by liquid chromatography tandem mass spectrometry (LC/MS/MS) using a Micromass Quattro Ultima and Shimadzu HPLC system equipped with a Phenomenex Synergi Polar-RP column (4.6 x 150 mm, 4 μm particle size), a mobile phase system consisting of acetonitrile:water:trifluoro acetic acid (20:80:0.05), and mass spectrometric detection with positive ionization by electrospray ionization and mass scanning by multiple reaction monitoring ([M+H]+ transitions of 150/119 (Q1/Q3) m/z for methamphetamine and 159/125 m/z for deuterated methamphetamine). The standard curve range of methamphetamine by LC/MS/MS analysis is 0.00800 nanograms (ng)/mg (lower limit) to 3.20 ng/mg of hair.

3. Validity - Weighted Surrogate Assessment

   Time frame: At enrollment visit (V0) and at follow-up visit (V1). The data will be collected as amount per day for the most recent day of use.

   Participants will work with the researchers to measure out a quantity of a non-psychoactive drug surrogate onto a physical milligram scale until the participant reports that the quantity matches their daily use. The min value of this scale is 0 and there is no max value. The actual score does not represent a better or worse outcome, rather we are comparing it to the reported value. To avoid potential use triggers associated with this procedure, it will be performed in a professional and clinical fashion, with the phenethylamine kept in laboratory glassware and handled with gloves and tweezers. This will be compared to the reported value to assess validity. This will be conducted at V0 and V1.

4. Acceptability Questionnaire

   Time frame: Follow-up visit (V1). The questionnaire will cover the time frame of the study, which will be 7-14 days.

   A questionnaire will be administered to assess the acceptability of the MAVS among people who use methamphetamine. This will be performed V1 and will consist of several 5-point Likert scale questions on the MAVS' ease of use, relevance to use patterns, and whether seeing the drug surrogate triggers a desire to use. A higher value on the scale measures higher acceptability.