Comparison of urine and oral fluid for workplace drug testing

Abstract

Aims: To determine the relative detection rates of urine versus oral fluid testing in a safety sensitive industry and the correlation with diagnosed substance use disorders and possible impairment at work.Methods: The trial involved 1,500 paired urine and oral fluid tests performed in accordance with Australian Standard/New Zealand Standard (AS/NZS) 4308:2008 and AS 4760:2006. Workers who returned a positive test were screened for substance use disorders, as defined by DSM-5, and for possible impairment at work following that particular episode of substance use.Results: Substances were detected in 3.7% (n = 56) of urine samples and 0.5% (n = 8) of oral fluid samples (p < 0.0001). One worker (0.07%) had a substance detected on oral fluid alone versus 49 workers (3.3%) who had substances detected on urine alone. Twelve workers returned a positive result, defined as being consistent with the use of an illicit drug or a controlled substance without a clinical indication and prescription. Nine workers tested positive on urine alone, one on oral fluid alone and two on both (p = 0.0114). Of note, 6/11 workers who tested positive on urine had possible impairment at work and 2/11 had a substance use disorder versus 2/3 and 0/3, respectively, who tested positive on oral fluid.Conclusions: Urine drug testing performed in accordance with AS/NZS 4308:2008 is more likely to detect overall substance use and illicit drug use than oral fluid testing conducted in accordance with AS 4760:2006. Urine testing performed in accordance with AS/NZS 4308:2008 may also be more likely to detect workers with possible impairment at work and substance use disorders than oral fluid testing performed in accordance with AS 4760:2006.