Lowering Cutoffs for Initial and Confirmation Testing for Cocaine and Marijuana: Large-Scale Study of Effects on the Rates of Drug-Positive Results (Drug Monitoring and Toxicology‪)‬

Five drug classes are monitored by the Substance Abuse and Mental Health Services Administration (SAMHSA), the federally regulated, civilian drug-testing program: cocaine (COC), marijuana (THC), amphetamines, phencyclidine, and opiates. (1) COC and THC are of primary interest because of their relatively high incidence, which is the result almost exclusively of abuse, their medical use being extremely limited. For the first 4 years after the inception of the SAMHSA drug-testing program, the initial testing (screening) and confirmation testing cutoffs for THC were 100 [micro]g/L and 15 [micro]g/L, respectively [1]; on September 1, 1994, the initial testing cutoff for cannabinoids was decreased to 50 [micro]g/L [2]. The initial testing and confirmation SAMHSA cutoffs for COC have remained at 300 [micro]g/L and 150 [micro]g/L, respectively. None of the other major civilian drug-testing programs such as the College of American Pathologists or New York State have mandatory reporting cutoffs for the urine drug-testing laboratories enrolled in their programs. The Department of Defense drug-testing program uses respective initial and confirmation test cutoffs of 50 and 15 [micro]g/L for THC and of 150 and 100 [micro]g/L for COC. The present study was undertaken to determine what cutoffs are obtainable with the methodologies now in use for COC and THC and whether applying lower cutoffs would lead to a significant increase in the rates of positive results found. Materials and Methods