Advancing Spectroscopy-Based Drug Checking Training: A Proof-of-Concept Study for the Use of Concordance Analysis

Drug checking is a harm reduction strategy that provides information to people who use drugs. Currently, there is a lack of standardised, replicable methods to assess drug checking technicians' use of spectroscopy-based technologies.

This paper introduces concordance analysis as a method to assess drug checking technician accuracy using Fourier transform infrared (FTIR) spectroscopy. Drug checking technicians provided point-of-care drug checking services, including FTIR, at participating syringe service programs in New York City beginning in November 2021. Drug checking technicians analysed drug samples and identified compounds based on spectra, test strips and contextual information provided by the individuals submitting samples. The drug checking technician results were compared to results obtained from a secondary laboratory testing partner. Technicians aimed to achieve a 90% concordance rate for sample composition determinations in the field as compared to secondary laboratory testing results.

Two drug checking technicians encountered a total of N = 362 samples over the course of their training periods. Concordance analysis showed that both technicians completed their training period above the target accuracy level (Technician A 137/151 or 90.7% concordant, Technician B 196/211 or 92.9% concordant). The training periods for Technician A and Technician B were 33 and 38 weeks, respectively. Both technicians demonstrated improvement over time.

These results indicate that drug checking technicians with no formal background in analytical chemistry are able to accurately identify compounds present in real-world drug samples using an FTIR, thus supporting the merit of these techniques in drug checking programs.