Usability Testing of Five Fentanyl Test Strip Brands in Real-World Settings

Fentanyl test strips (FTS) are a forensic tool designed for laboratory testing of urine samples. They have been adapted into a point-of-consumption drug-checking tool to detect illegally manufactured fentanyl in local drug supply. This creates unknown usability challenges for people who use drugs (PWUD). To assess ease of use in real-world settings, we conducted usability testing of five FTS brands. Six researchers independently completed a REDCap survey to evaluate usability of five FTS brands before and after testing a baking soda sample prepared in their homes. The survey first assessed ease of use of specific brand features, then usability of each brand as an interactive system with the System Usability Scale (SUS). DanceSafe scored highest on ease of use ratings and highest on the SUS (above the usability threshold of ≤68). Dosetest scored lowest on ease of use ratings and below the SUS usability threshold. Respondents identified usability challenges with all brands, including difficulty opening single-strip envelopes, complex instruction design, and instruction discrepancies. Design of all brands assumes users have required testing resources (e.g. water, measuring tools, an Internet connection, and a timer), yet no brand provides these. FTS are complex interactive systems not fully adapted for testing in real-world settings. The complexity of FTS may lead to testing error or limit their adoption by PWUD. We encourage manufacturers to design FTS directly for PWUD by considering resource limitations of real-world testing settings, human factors, and local supply complexity.