More training needed to ensure accuracy of urine drug tests

In a survey of primary care physicians, most reported not using proper techniques when collecting urine samples for drug tests on adolescents and were often unaware of the tests' limitations, according to an article in the Archives of Pediatrics & Adolescent Medicine.

During the past 25 years, drug testing has become increasingly popular in the U.S., according to background information in the article. In 1995, the Supreme Court ruled that high schools may require student athletes to undergo drug testing. The Office of National Drug Control Policy encourages schools to perform urine drug tests on all students, stating that testing can help recognize students with drug problems while acting as a deterrent for others. Drug tests that are performed incorrectly, however, can result in false accusations or false reassurance.

Sharon Levy, M.D., M.P.H., of Harvard Medical School and Children's Hospital Boston, and colleagues, surveyed primary care physicians about their knowledge of urine drug testing and their typical practices when conducting drug tests. To be included in the survey, physicians had to see 10 or more adolescent patients (aged 12 to 18 years) per week. From April to July 2004, approximately 360 physicians completed the survey, more than 95 percent of whom had ever ordered a drug test.

The researchers said that a properly collected urine sample included being sure that patients provide identification, empty their pockets and use the bathroom without running water; the sample is checked immediately for temperature; blue dye is placed in standing water; and a staff member directly observes the patient or is present inside the bathroom.

Only 23 percent of physicians used an effective method of collecting urine samples, and only ten percent of physicians knew that nitrous oxide, ecstasy and oxycodone were not detectable by standard urine tests. Almost one-third did not know that alcohol used in cooking would not cause a false positive alcohol screening result. Responding to the question of whether or not eating large quantities of poppy seeds can cause positive results for opioids, codeine and/or morphine, 40 percent of physicians either did not know or answered incorrectly. (Poppy seeds can cause a positive drug test results.) The surveyed physicians were also unsure of whether second-hand exposure to marijuana smoke would cause a positive result on a drug test, with 61 percent of physicians answering incorrectly or with "don't know."

"This study shows that although most primary care physicians order urine drug tests, most do not use recommended procedures for urine test collection, validation and confirmation and lack the knowledge needed to correctly interpret positive and negative results," the study authors write. "Physicians and parents may be falsely reassured that their child is not using a particular drug when the child never underwent proper testing for it.Misinterpretation of a false-positive finding can put adolescents at risk for false accusation of substance use and diminished trust from parents, school personnel and counselors."