Clinical Textbook of Addictive Disorders 3rd ed - R. Frances, S. Miller, A. Mack (Guilford, 2005) WW

66 II. ASSESSMENT OF ADDICTIONINTERPRETATIONIn an ideal world, testing biological samples should lead to definitive answers.However, test results sometimes lead to more questions than answers. Adeptinterpretation of results will lead to improved clinical care or to more surety inconsultative cases. Interpretation depends on awareness of which test was usedand its meaning to the situation.In most settings, the primary purpose of drug testing is to identify individualswho are using illegal or illicit drugs. Falsely accusing someone of using drugsis highly problematic and undermines the testing program. Similarly, not beingable to identify active drug users because of false-negative results renders a programof limited value. It does not deter use or identify users. This is so both forthe emergency room physician wondering if the agitated patient used PCP, andfor the consultant to the local college track team. For these situations, highlysensitive qualitative screening tests should be employed, even if this leads tosome false-positive results. On the other hand, definitive tests should have thehighest level of specificity: They should exclude as many true negatives as possible.For nonusers who are subjected to drug testing, issues related to falsepositiveresults are of great concern. Questions addressing which foods, prescribedmedications, dietary supplements, or potentially secondhand marijuanasmoke could result in a positive test are common, and some laboratories haveresponded by raising the level required in order to render a positive test result.With the proliferation of private laboratories and commercially manufacturedkits, there has grown to be some interlaboratory variation in standardsand thresholds for results. The industry even has its own trade organization, theDrug and Alcohol Testing Industry Association (DATIA). The major concernin drug testing occurs with the reporting of laboratory results. Unlike NationalInstitute on Drug Abuse (NIDA)–certified testing of the Standard Drug Panel(see Table 4.2), clinical drug testing for drugs of abuse currently has no standardtechnical criteria, no standard screening cutoffs for positive tests, no confirmationcutoffs, no chain-of-custody requirements, no blind proficiency submissionrequirements, and no certification programs. As a result, a sample testing posi-TABLE 4.2. “NIDA 5” or the DOT StandardDrug Panel 1990DrugCutoffs (ng/ml)Cocaine 300/150Cannabinoids 50/15PCP 25/25Opiates 2,000/2,000Amphetamines 1,000/500