Summary of Recommendations and Evidence

The U.S. Preventive Services Task Force (USPSTF) concludes that the current evidence is insufficient to assess the balance of benefits and harms of screening adolescents, adults, and pregnant women for illicit drug use (Table 1). I statement.

Rationale

Importance. Illicit drug use and abuse are serious problems among adolescents, adults, and pregnant women in the United States, ranking among the 10 leading preventable risk factors for years of healthy life lost to death and disability in developed countries. (Tobacco use and alcohol misuse are considered in separate screening recommendations of the USPSTF.)

Detection. Although standardized questionnaires to screen adolescents and adults for drug use or misuse have been shown to be valid and reliable, there is insufficient evidence to assess the clinical utility of these instruments when applied widely in primary care settings.

Benefits of detection and early treatment. There is good evidence that various treatments are effective in reducing illicit drug use in the short term. Evidence is insufficient, however, to demonstrate that treatment reliably improves social and legal outcomes in patients, or to link treatment directly to longer-term improvements in morbidity or mortality. Because all but one published clinical trial of treatment interventions involved persons who had already developed problems from their drug use, it is not known whether the findings are generalizable to asymptomatic persons whose illicit drug use is detected through screening. There is fair evidence that, regardless of the patient's history of treatment, reducing or stopping drug use is associated with improvement in some health outcomes.

Harms of detection and early treatment. There is little evidence of harms associated with screening for illicit drug use or behavioral interventions used in treatment. Several clinical trials of pharmacotherapy for drug misuse have reported mild to serious adverse events, although some of these events were likely related to underlying drug use. The specific adverse events noted to occur more often in the treatment arm of trials (compared with placebo) have been previously recognized as potential side effects of the treatment medication and cited on its product label.

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

Clinical Considerations

• Patient population. Although the rate of illicit drug use in the United States is highest in persons between 18 and 20 years of age, more than 10 percent of adolescents 12 to 17 years of age are known to use illicit drugs. The percentage of adults who regularly use illicit drugs decreases steadily with age. About 5 percent of pregnant women report using illicit drugs within the previous month.

• Patterns of drug use. Marijuana is the most commonly used illicit drug in the United States, with about 6 percent of the population 12 years and older admitting to use within the previous month. Although cocaine is the second most commonly used illicit drug, it is used by less than 1 percent of the population. Only a small minority of Americans uses hallucinogens, inhalants, heroin, or illicitly manufactured methamphetamine, although the potential for abuse of or dependence on these substances is high. Illicit (nonmedical) use of prescription-type drugs, categorized as pain relievers, tranquilizers, stimulants, and sedatives, is a growing health problem in the United States.

• Screening tests. Although physicians should be alert for the signs and symptoms of illicit drug use in patients, the added benefit of screening asymptomatic patients in primary care practice remains unclear. Toxicologic tests 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. A few brief, standardized questionnaires have been shown to be valid and reliable in screening adolescent and adult patients for drug use or misuse. However, the clinical utility of these questionnaires is uncertain. The reported positive predictive values are variable and at best 83 percent when the questionnaires are applied in a general medical clinic. Moreover, the feasibility of routinely incorporating the questionnaires into busy primary care practices has yet to be assessed. The validity, reliability, and clinical utility of standardized questionnaires in screening for illicit drug use during pregnancy have not been adequately evaluated.

• Treatment. Although drug-specific pharmacotherapy (e.g., buprenorphine for opiate abuse) alone or in combination with behavioral interventions (e.g., 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 been inadequately evaluated. These treatments have been studied almost exclusively in persons who have already developed medical, social, or legal problems from drug use, and their effectiveness in persons identified through screening remains unclear. In all but one trial, treatment was delivered outside the primary care setting, often in specialized treatment facilities. More evidence is needed on the effectiveness of office-based treatments for illicit drug use and dependence.

• Other approaches to prevention. Although interventions to prevent or reduce illicit drug use have been proposed for use in schools and sites of employment, evidence assessing preventive measures delivered in settings other than primary care practice was outside the scope of the USPSTF review. However, the Centers for Disease Control and Prevention's Task Force on Community Preventive Services has announced plans to assess the effectiveness of selected population-based interventions for preventing or reducing abuse of drugs (other than tobacco and alcohol) and to make recommendations based on these findings.