Screening teens for substance abuse: a long way to go
Urine testing carries a substantial risk for error, study finds
April 2, 2007
In confidential surveys, 40 percent of 12th graders report having used an illicit drug in the past year, and some policymakers -- as well as test manufacturers -- are currently pushing for random school- and home-based drug testing. But a study in the April Pediatrics, from Children's Hospital Boston's Center for Adolescent Substance Abuse Research, found that laboratory drug testing carries a substantial risk for error, even when performed as part of an established adolescent substance abuse program.
Researchers Sharon Levy, MD, MPH, and colleagues reviewed 710 random urine drug tests from 110 of their patients, aged 13 to 21, and compared the results with confirmatory laboratory tests. (All the patients were prior drug users and had agreed to random testing as part of their treatment.)
Overall, 12 percent of the random tests had results that were subject to misinterpretation. Of 480 negative tests, 8 percent were from urine samples that were too dilute to reliably interpret, despite being collected under controlled conditions. (Seventeen percent of adolescents submitted at least one dilute sample.) Of 217 positive test results, 21 percent were attributable to legitimate prescription or over-the-counter medications. Finally, of the samples confirmed positive for Oxycontin use, two-thirds had initially tested negative.
The researchers conclude that given the high potential for misinterpretation, there is no justification for widespread implementation of drug testing programs, unless those programs are prepared to be thorough and rigorous, with well-trained personnel who can observe sample collection and ask follow-up questions. They also note that not all drugs abused by adolescents are reliably detected by standard screening panels; Oxycontin is one such example.
"Drug testing is more technically complex than most clinicians and policymakers appreciate," says Levy. "Many adolescents are adept at defeating urine tests, and extensive, rigorous testing can be prohibitively expensive. The resources put into testing would be better spent on prevention and treatment programs. Drug testing should be reserved for patients with a clinical indication for this procedure, and when drug testing is indicated, the best available procedures should be used."
A related study, published online by the Journal of Adolescent Health in February, found that primary-care pediatricians feel ill-prepared to screen their adolescent patients for substance abuse. Shari Van Hook, MPH, John Knight, MD, and colleagues from Children's Center for Adolescent Substance Abuse Research conducted focus groups with 38 pediatric doctors and nurses at six primary-care sites. The participants identified six main barriers to screening: lack of time, lack of training to deal with positive screens, lack of familiarity with screening tools, parents' refusal to leave the room for a confidential doctor-patient discussion, other conditions competing for medical attention, and lack of resources to treat substance abuse problems.
In March, an American Academy of Pediatrics policy statement, coauthored by Knight, concluded that school- and home-based drug testing is not enough to prevent adolescent substance abuse, and more research needs to be done before such testing can be recommended. (Read the news release for more information.)
Children's Hospital Boston is home to the world's largest research enterprise based at a pediatric medical center, where its discoveries have benefited both children and adults since 1869. More than 500 scientists, including eight members of the National Academy of Sciences, 11 members of the Institute of Medicine and 10 members of the Howard Hughes Medical Institute comprise Children's research community. Founded as a 20-bed hospital for children, Children's Hospital Boston today is a 347-bed comprehensive center for pediatric and adolescent health care grounded in the values of excellence in patient care and sensitivity to the complex needs and diversity of children and families. Children's also is the primary pediatric teaching affiliate of Harvard Medical School. For more information about the hospital and its research visit: www.childrenshospital.org/newsroom.
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