Putting Prevention into Practice

An Evidence-Based Approach

Screening for Illicit Drug Use

Am Fam Physician. 2009 Sep 15;80(6):629-630.

This clinical content conforms to AAFP criteria for evidence-based continuing medical education (EB CME). See CME Quiz on page 573.

Case Study

An 18-year-old woman visits your office for routine prenatal care. She is in the first trimester of pregnancy and has had no notable medical problems. The physical examination is normal, and she expresses no concerns.

Case Study Questions

  1. Which one of the following actions is most consistent with the U.S. Preventive Services Task Force (USPSTF) recommendation on screening for illicit drug use?

    • A. Perform a urine drug screen.

    • B. Administer a validated, standardized questionnaire for illicit drug use.

    • C. Draw blood for toxicology.

    • D. Remain alert for signs and symptoms of illicit drug use, but do not screen with standardized questionnaires, blood tests, or urine tests.

    • E. Ask the patient if she uses illicit drugs, because there is good evidence that treating identified patients improves social and legal outcomes.

  2. Which one of the following statements about screening for illicit drug use is correct?

    • A. Interventions to reduce illicit drug use have been shown to improve long-term health outcomes.

    • B. Validated screening questionnaires are clinically useful in primary care settings.

    • C. The USPSTF found little evidence of harms associated with screening for illicit drug use.

    • D. The benefits of screening for illicit drug use outweigh the potential harms.

    • E. Blood or urine tests can distinguish between persons who use illicit drugs occasionally and those who are functionally impaired from drug use.

  3. Which of the following statements about illicit drug use in the United States is/are correct?

    • A. Marijuana is the most commonly used illicit drug.

    • B. The rate of illicit drug use is highest in patients 18 to 20 years of age.

    • C. The benefits of screening for illicit drug use in pregnant women are well established.

    • D. There is insufficient evidence of the effectiveness of treating illicit drug use in persons identified by screening.

Answers

1. The correct answer is D. Physicians should be alert to signs and symptoms of illicit drug use in patients; however, blood and urine tests are not recommended. Toxicology of blood or urine can provide objective evidence of drug use, but such tests do not distinguish between persons who use illicit drugs occasionally and those who are impaired by drug use.

Although certain screening questionnaires have demonstrated validity in detecting illicit drug use in adolescent and adult populations with a higher prevalence of drug use or misuse (i.e., treatment-seeking populations), the accuracy of these tests in the general population (which has a predictably lower prevalence of drug use or misuse) is unknown.

Reducing or stopping drug misuse is associated with improvement in some health outcomes. However, there is insufficient evidence to demonstrate that treatment reliably improves social or legal outcomes for patients.

2. The correct answer is C. The USPSTF found little evidence of harms associated with screening for illicit drug use. However, failure to protect the confidentiality of positive results could potentially affect a patient's employment, insurance coverage, or personal relationships.

Although certain behavioral interventions, such as brief motivational counseling for marijuana misuse, have been proven effective in reducing illicit drug use in the short term, the longer-term effects of treatment on morbidity and mortality have not been adequately evaluated.

A few validated screening instruments are short enough to be used routinely in primary care settings, but the clinical utility of these questionnaires remains uncertain.

The USPSTF concludes that for adolescents, adults, and pregnant women, the evidence is insufficient to determine the balance of benefits and harms of screening for illicit drug use.

3. The correct answers are A, B, and D. Marijuana is the most commonly used illicit drug in the United States, with 6 percent of persons 12 years and older admitting to use within the previous month. The rate of illicit drug use is highest among persons 18 to 20 years of age.

The USPSTF did not find direct evidence of the benefits of screening for illicit drug use in pregnant women, adolescents, or adults.

Treatments for illicit drug use have been studied almost exclusively in persons who have already developed medical, social, or legal problems from drug use. The effectiveness of treating asymptomatic persons identified through screening for illicit drug use remains unclear.

SOURCES

U.S. Preventive Services Task Force. Screening for illicit drug use: recommendation statement. Rockville, Md.: Agency for Healthcare Research and Quality; 2008. http://www.ahrq.gov/clinic/uspstf08/druguse/drugrs.htm. Accessed July 1, 2009.

Lanier D, Ko S. Screening in primary care settings for illicit drug use: assessment of screening instruments—a supplemental evidence update for the US Preventive Services Task Force Evidence synthesis no 58, part 2 Rockville, Md: Agency for Healthcare Research and Quality; 2008. http://www.ahrq.gov/clinic/uspstf08/druguse/drugevup.pdf. Accessed July 1, 2009.

Polen MR, Whitlock EP, Wisdom JP, Nygren P, Bougatsos C. Screening in primary care settings for illicit drug use: staged systematic review for the U.S. Preventive Services Task Force. Evidence synthesis no. 58, part 1. Rockville, Md.: Agency for Healthcare Research and Quality; 2008. http://www.ahrq.gov/clinic/uspstf08/druguse/drugsys.pdf. Accessed July 1, 2009.

The case study and answers to the following questions on screening for illicit drug use are based on the recommendations of the U.S. Preventive Services Task Force (USPSTF), an independent panel of experts in primary care and prevention that systematically reviews the evidence of effectiveness and develops recommendations for clinical preventive services. More detailed information on this subject is available in the USPSTF Recommendation Statement and the systematic evidence review on the USPSTF Web site (http://www.ahrq.gov/clinic/uspstfix.htm). The practice recommendations in this activity are available at http://www.ahrq.gov/clinic/uspstf/uspsdrug.htm.


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