What Is the Issue?

• Drug toxicity and related death have been declared a public health emergency in Canada, driven largely by increasingly toxic unregulated fentanyl and opioid supplies contaminated with unexpected, high-potency opioids and other central nervous system and/or respiratory depressants (e.g., benzodiazepine, xylazine).
• Drug-checking technologies (DCTs) — referring here to the underlying analytical methods such as immunoassay or mass spectrometry — are used to determine the presence of specific substances or provide a comprehensive breakdown of the substance’s composition. DCTs are used as part of drug-checking services to support safer use, increase awareness of substance compositions, connect people with health and social services, and inform public health responses to the toxic drug supply.
• There is a need to synthesize the available DCT evidence on accuracy, limit of detection, repeatability, reproducibility, cost-effectiveness, and costs for detecting compositions of unregulated substance samples.

What Did We Do?

• Based on the results of an initial scoping exercise and experts’ feedback, we conducted a customized health technology review to inform decisions regarding the use of DCTs for detecting compositions of unregulated substance samples.
• We searched key resources, including journal citation databases, and conducted a focused internet search, with no publication date limits, for relevant evidence. We also sought costing information by contacting DCT manufacturers to obtain costing estimates in Canadian dollars.

What Did We Find?

• The body of evidence on the outcomes and capabilities of DCTs is small but growing.
• We found 18 test accuracy studies that evaluated the accuracy of any DCTs for detecting compositions of unregulated substance samples.
  • DCTs varied in accuracy outcomes depending on the substance and context. Immunoassay test strips (ITS) showed relatively high sensitivity and low to minimal false negative rates for target substances, whereas spectroscopic methods (e.g., Fourier transform infrared [FTIR] spectroscopy spectrometers) provided broader compositional information.
  • Combining or advancing technologies improved performance. Pairing methods, such as FTIR with ITS, or using emerging DCTs, including portable gas chromatography–mass spectrometry and surface-enhanced Raman spectroscopy, enhanced sensitivity and reduced false negative rates.
  • Colorimetric reagents and infrared spectroscopy were shown to have comparable high sensitivity against the confirmatory lab testing.
• We found 7 test accuracy studies that evaluated the limit of detection of any DCTs for detecting compositions of unregulated substance samples. Of these, 1 study also reported on the reproducibility of ITS. This review did not find any studies that reported results on the repeatability of DCTs that met our selection criteria for this review.
  • ITS (e.g., fentanyl test strips), FTIR, and hand-held Raman spectrometers were each able to detect the presence of target substances in samples, though their detection capabilities varied depending on the substance and concentration.
  • Xylazine test strips consistently detected xylazine in samples with low concentrations, across days.
• We did not find any studies on the relative cost-effectiveness of any DCTs for detecting compositions of unregulated substance samples that met our selection criteria for this review.
• We found 1 article that provided a cost description of a US pilot drug-checking service that employed an FTIR spectroscopy, fentanyl test strips, and confirmatory lab testing. The findings demonstrated the feasibility of drug checking in the evaluated context.
• Eleven manufacturers that we contacted provided cost information by completing surveys for 16 DCTs. Among the cost data received, 4 DCTs were technologies identified in the included test accuracy studies.
• Outcome measures and methods used for evaluation of DCTs were heterogeneous across the studies, and conclusions were often constrained by risks of bias and applicability. No studies were found that specifically address the performance of DCTs in distinct settings, such as rural or Indigenous communities. Well-designed, methodologically rigorous studies are needed to generate the evidence needed to confirm the accuracy and cost-effectiveness of DCTs.

What Does This Mean?

• This review includes several considerations for health care decision-makers, including those planning or implementing DCTs for use in clinical and community settings:
  • There is a trade-off between highly sensitive detection of a single substance (e.g., fentanyl) and broader screening capacity: ITS indicated high sensitivity and specificity in detecting target substances and may be used for early identification of toxic substances and their analogues; however, FTIR and Raman spectrometers offer the advantage of detecting multiple substances within a single sample.
  • A multitool approach may be preferable for drug checking and may better guide harm reduction messaging for people who use drugs: pairing point-of-care FTIR spectrometry and ITS combined with confirmatory lab testing can enhance sensitivity and reduce the false negative rate.
  • In the context of drug checking, certain test accuracy measures are more critical than others: studies most often reported on sensitivity, reflecting the importance of avoiding false negative results (i.e., failing to detect a harmful substance), and specificity, reflecting the problems with false positives, which can generate misinformation about the unregulated drug supply.
  • Innovations in emerging DCTs are specifically intended to balance trade-offs between sensitivity, specificity, cost, and ease of use. Most of these technologies are in the research, development, and evaluation stages, and some are in the field-testing stage.
  • Establishing national or regional guidelines for evaluation metrics, accuracy reporting, and service design specific for evaluation of DCTs may reduce variability in evidence.
  • Relevant costing estimates obtained from DCT manufacturers included in this report can be considered alongside operational and contextual factors (e.g., service delivery model, staff capacity, proximity to confirmatory testing facilities) when considering, planning, or implementing DCTs within their specific settings.
  • Along with the technical and cost considerations, ethics and equity considerations relevant to the context of DCTs, presented in this report, can be considered including those related to consent, access, legal requirements, and privacy.