A therapeutic tool as part of evidence-based addiction treatment, clinical drug testing should embrace the principles of “smarter” testing, according to a consensus statement issued by the American Society of Addiction Medicine. Smarter testing principles include: random rather than scheduled testing; testing not only urine samples but also other matrices; testing for a broad and rotating clinically indicated panel of drugs; and carefully considering financial costs and value as well as the advantages and limitations of testing methods.
Addiction medicine providers also need to consult upfront with directors of labs they’re considering working with for a clear discussion of the test panels, procedures, and technical assistance the labs offer.
The statement recommends that physicians choose a testing matrix—whether blood, urine, oral fluids, exhaled breath, sweat, or hair— that best answers the clinical question at hand. Matrices vary in sensitivity and specificity, but rotating them may reduce the potential for sample adulteration. “Tests should be chosen based on the information they are expected to reveal. All tests are designed to answer certain questions and all tests have limitations,” the authors noted. Presumptive testing relies mainly on immunoassays, with positive results needing confirmation by an independent chemical method such as gas chromatography mass spectrometry or liquid chromatography-mass spectrometry.
Between presumptive and definitive tests, the authors recommended that providers use presumptive tests in cases where immediate results take higher priority over accuracy. Definitive tests come into play when a presumptive test’s findings are disputed, or if a clinician is looking for a specific substance that presumptive test couldn’t find. “Providers should contact the testing laboratory if they have any questions about interpreting a test result or to request information about the laboratory procedures that were used,” the authors advised.
Formal lab analysis remains the preferred method for high stakes definitive tests, yet advances in point-of-care tests (POCT) may be changing this dynamic. “Newer POCT analyzers have significantly greater quality control and rival central laboratory analysis in terms of their sensitivity and specificity,” the authors observed. They also underscored the importance of POCT proficiency testing and education for any POCT device users.
The authors also had plenty of advice to give about selecting a laboratory for clinical addiction testing. Providers should discuss with the director or medical toxicologist of any prospective lab the panels, types of tests, testing procedures, and technical assistance the lab offers. They should look particularly for labs that allow providers to order specific tests for patients, in keeping with the principle of individualized addiction treatment.
The authors also stressed the importance of choosing a lab willing and able to assist with interpreting results. “Providers should work to create a collaborative relationship with the laboratory; important areas for collaboration are test panel selection, detecting sample tampering, interpreting test results, and regional drug use trends,” the guideline authors advised.