An assessment of the limits of detection, sensitivity and specificity of three devices for public health-based drug checking of fentanyl in street-acquired samples

Abstract

Background: Fentanyl has caused rapid increases in US and Canadian overdose deaths, yet its presence in illicit drugs is often unknown to consumers. This study examined the validity in identifying the presence of fentanyl of three portable devices that could be used in providing drug checking services and drug supply surveillance: fentanyl test strips, a hand-held Raman Spectrometer, and a desktop Fourier-Transform Infrared Spectrometer.

Methods: In Fall 2017, we first undertook an assessment of the limits of detection for fentanyl, then tested the three devices' sensitivity and specificity in distinguishing fentanyl in street-acquired drug samples. Utilizing test replicates of standard fentanyl reference material over a range of increasingly lower concentrations, we determined the lowest concentration reliably detected. To establish the sensitivity and specificity for fentanyl, 210 samples (106 fentanyl-positive, 104 fentanyl-negative) previously submitted by law enforcement entities to forensic laboratories in Baltimore, Maryland, and Providence, Rhode Island, were tested using the devices. All sample testing followed parallel and standardized protocols in the two labs.

Results: The lowest limit of detection (0.100 mcg/mL), false negative (3.7%), and false positive rate (9.6%) was found for fentanyl test strips, which also correctly detected two fentanyl analogs (acetyl fentanyl and furanyl fentanyl) alone or in the presence of another drug, in both powder and pill forms. While less sensitive and specific for fentanyl, the other devices conveyed additional relevant information including the percentage of fentanyl and presence of cutting agents and other drugs.

Conclusion: Devices for fentanyl drug checking are available and valid. Drug checking services and drug supply surveillance should be considered and researched as part of public health responses to the opioid overdose crisis.

Keywords: Drug checking; Fentanyl; Harm reduction; Overdose; Public health; Surveillance.