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Case Study

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

Case Study Questions1. Which one of the following actions is most consistent with the U.S. Preventive ServicesTask 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 appear on the following page.

Screening for Illicit Drug UseKENNETH W. LIN, MD,Medical Officer, U.S. Preventive Services Task Force Program,

Agency for Healthcare Research and Quality

VAL W. FINNELL, MD, MPH, General Preventive Medicine Residency, Uniformed Services University of the Health Sciences

The case study andanswers to the followingquestions on screening forillicit drug use are basedon the recommendationsof the U.S. Preventive Ser-vices Task Force (USPSTF),an independent panel ofexperts in primary careand prevention that sys-tematically reviews theevidence of effectivenessand develops recom-mendations for clinicalpreventive services. Moredetailed information onthis subject is availablein the USPSTF Recom-mendation Statement andthe systematic evidencereview on the USPSTF Web

site (http://www.ahrq.gov/clinic/uspstfix.htm).The practice recommenda-tions in this activity areavailable at http://www.ahrq.gov/clinic/uspstf/uspsdrug.htm.

This clinical content con-forms to AAFP criteria forevidence-based continuingmedical education (EBCME). See CME Quiz on

page 573.

Putting Prevention into PracticeAn Evidence-Based Approach

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Answers

1. The correct answer is D. Physicians shouldbe alert to signs and symptoms of illicit druguse in patients; however, blood and urinetests are not recommended. Toxicology of

blood or urine can provide objective evidenceof drug use, but such tests do not distinguishbetween persons who use illicit drugs occa-sionally and those who are impaired by druguse.

Although certain screening questionnaireshave demonstrated validity in detecting illicitdrug use in adolescent and adult populationswith a higher prevalence of drug use or mis-use (i.e., treatment-seeking populations), theaccuracy of these tests in the general popula-tion (which has a predictably lower preva-

lence of drug use or misuse) is unknown.Reducing or stopping drug misuse is asso-

ciated with improvement in some healthoutcomes. However, there is insufficientevidence to demonstrate that treatmentreliably improves social or legal outcomesfor patients.

2. The correct answer is C. The USPSTFfound little evidence of harms associatedwith screening for illicit drug use. However,failure to protect the confidentiality of posi-tive results could potentially affect a patientsemployment, insurance coverage, or personalrelationships.

Although certain behavioral interven-tions, such as brief motivational counselingfor marijuana misuse, have been proveneffective in reducing illicit drug use in theshort term, the longer-term effects of treat-ment on morbidity and mortality have notbeen adequately evaluated.

A few validated screening instruments are

short enough to be used routinely in pri-mary care settings, but the clinical utility ofthese questionnaires remains uncertain.

The USPSTF concludes that for adoles-cents, adults, and pregnant women, theevidence is insufficient to determine thebalance of benefits and harms of screeningfor illicit drug use.

3. The correct answers are A, B, and D.

Marijuana is the most commonly used illicitdrug in the United States, with 6 percent ofpersons 12 years and older admitting to usewithin the previous month. The rate of illicitdrug use is highest among persons 18 to20 years of age.

The USPSTF did not find direct evidenceof the benefits of screening for illicit druguse in pregnant women, adolescents, oradults.

Treatments for illicit drug use have beenstudied almost exclusively in persons whohave already developed medical, social, orlegal problems from drug use. The effec-tiveness of treating asymptomatic personsidentified through screening for illicit druguse remains unclear.

SOURCES

U.S. Preventive Services Task Force. Screening for illicitdrug 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 set tings forillicit drug use: assessment of screening instrumentsa supplemental evidence update for the U.S. PreventiveServices Task Force. Evidence synthesis no. 58, part 2.Rockville, Md.: Agency for Healthcare Research andQuality; 2008. http://www.ahrq.gov/clinic/uspstf08/druguse/drugevup.pdf. Accessed July 1, 2009.

Polen MR, Whitlock EP, Wisdom JP, Nygren P, Bougat-sos C. Screening in primary care settings for illicit druguse: staged systematic review for the U.S. PreventiveServices Task Force. Evidence synthesis no. 58, part 1.

Rockville, Md.: Agency for Healthcare Research andQuality; 2008. http://www.ahrq.gov/clinic/uspstf08/druguse/drugsys.pdf. Accessed July 1, 2009.