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National Institute on Alcohol Abuse and Alcoholism

No. 56
April 2002

Screening for Alcohol Problems—An Update

The prevalence of alcohol use disorders is significantly higher among patients visiting a primary care practitioner than among the general population (1,2). For this reason, clinicians have the opportunity to play a key role in detecting alcohol problems and in initiating prevention or treatment efforts. A variety of relatively brief screening instruments are available for this purpose (3–5). These instruments do not provide a diagnosis, but help identify patients who might benefit from a more thorough assessment of their drinking behavior (6). Following screening, the presence of an alcohol use disorder can be confirmed using standard clinical diagnostic criteria. The success of this approach has been demonstrated. In one study, 80 percent of patients whose screening results were confirmed by a formal diagnosis of alcohol dependence accepted referrals to alcoholism treatment programs (7).

Patients should be screened not only for alcohol use disorders, but also for drinking patterns or behaviors that may place them at increased risk for developing adverse health effects or alcoholism (i.e., risky drinking) (5). Risky drinkers who have not yet become alcohol dependent often can be treated successfully within the primary care setting (8).

This Alcohol Alert presents information on selected screening instruments for use with primary care patients as well as other patient populations among whom alcohol use is either highly prevalent or hazardous.

Types of Instruments

Two types of alcoholism-screening instruments are available. The first type includes self-report questionnaires and structured interviews; the second type includes clinical laboratory tests that can detect biochemical changes associated with excessive alcohol consumption. The value of a screening instrument for measuring alcohol problems or other conditions is related to its sensitivity and specificity. Sensitivity refers to a test's accuracy in identifying people who have an alcohol problem (i.e., people with the condition test positive). Specificity refers to the test's effectiveness in identifying people who do not have an alcohol problem (i.e., people without the disease test negative).

No screening instrument is perfect. It is not possible to optimize both sensitivity and specificity in the same screening instrument. The likelihood of overidentifying alcohol use disorders occurs with increased sensitivity and the possibility of missing people who have an alcohol problem grows with increased specificity. Despite these limitations, research supports the use of formal screening instruments to increase the recognition of alcohol problems (5,9).

Questionnaires

Screening instruments vary in their ability to detect different patterns and levels of drinking and in the degree of their applicability to specific subpopulations and settings (2). This section compares features of some of the most widely used screening questionnaires. Detailed information is available at the NIAAA Web site (http://www.niaaa.nih.gov).

The CAGE questionnaire (10) has been evaluated in several studies, showing sensitivities ranging from 43 to 94 percent for detecting alcohol abuse and alcoholism (5). CAGE is well suited to busy primary care settings because it poses four straightforward yes/no questions that the clinician can easily remember and requires less than a minute to complete. However, the test may fail to detect low but risky levels of drinking (5). In addition, CAGE often performs less well among women and minority populations (11,12).

The performance of CAGE can be improved by incorporating questions about the quantity and frequency of drinking, as recommended by NIAAA in The Physicians' Guide to Helping Patients With Alcohol Problems (13). A study found that the screening strategy suggested in the Physicians' Guide effectively identified alcohol abuse and dependence in a general population sample (14). The same approach also demonstrated better sensitivity and similar specificity compared with CAGE alone among African American patients in an urban emergency room (15).

The Alcohol Use Disorders Identification Test (AUDIT) (16) also incorporates questions about quantity and frequency of alcohol use. In contrast to CAGE, AUDIT compares favorably with other instruments in detecting risky drinking, but is less effective in identifying alcohol abuse and alcoholism (5,17). Originally developed for primary care settings, AUDIT has proven useful among medical and psychiatric inpatients, in emergency rooms (17), and in the workplace (17–19). AUDIT is relatively free of gender and cultural bias (11,17,20). In addition, it shows promise for screening adolescents and older people, populations in which standard screening instruments produce inconsistent results (12,17,21–23). The major disadvantage of AUDIT is its length and relative complexity; clinicians require training to score and interpret the test results (3).

Screening pregnant women for alcohol use has become increasingly important in light of new research showing that even low levels of prenatal alcohol exposure can harm the fetus. Unfortunately, although approximately 20 percent of women consume some alcohol during pregnancy, maternal drinking can be difficult to detect (24). At least two questionnaires are available that are appropriate for pregnant women, both derived in part from CAGE. T–ACE (25) takes approximately 1 minute to complete and is more accurate than AUDIT for detecting current alcohol consumption and risky drinking, as well as a history of past alcoholism; however, it is less specific (24). The five-item TWEAK (26) performs similarly to T–ACE (24) and can be used to detect a range of drinking levels from moderate to high-risk consumption (27).

Alcohol consumption plays a role in a large percentage of trauma incidents, including motor vehicle crashes. RAPS4 is a four-item questionnaire derived in part from TWEAK and AUDIT. In both primary care and emergency room settings, RAPS4 showed consistently high sensitivity for detecting alcoholism across gender and ethnic subgroups, although its utility for screening for risky drinking or alcohol abuse has yet to be proven (28,29).

Computer-Assisted Screening. Computers have been widely and successfully used in screening and in assisting alcoholism intervention (17,30). Studies have found no significant difference in accuracy between computerized and paper-and-pencil versions of AUDIT among inpatient alcoholics (31). Similar results have been achieved with CAGE in the primary care setting (31). In addition, small laptop computers have been used in large-scale alcohol screening surveys. For example, in Audio Computer Assisted Self-Interviewing (ACASI), a recorded voice asks questions that can be answered by pressing a few keys. Advantages include ease of use for respondents with poor literacy or computer skills, as well as increased privacy, although the interviewer remains nearby to offer assistance if necessary (32).

The Internet provides an increasingly accessible, low-cost medium for screening and brief intervention (30). A pilot web site incorporating AUDIT and other alcohol history questions attracted more than 10,000 people during an initial 172-day trial. Of 2,253 people who took the test, 89 percent had scores suggesting harmful drinking or alcoholism, although 94 percent of participants of the total sample had never been diagnosed (30). The procedure is completely automated and self-administered.

Biological Markers

In contrast to self-report questionnaires, clinical laboratory procedures provide objective evidence of problem drinking. They are generally less sensitive and specific than questionnaires, but are valuable for corroborating results of interviews and questionnaires (33). The accuracy of these markers is affected by various factors such as nonalcoholic liver damage, use of medications or drugs, and by metabolic disorders. Three widely used tests and one promising new marker are described here.

Gamma-glutamyl transferase (GGT) is the most commonly used biochemical measure of drinking (33). Chronic drinking of 4 or more drinks per day for 4 to 8 weeks significantly raises levels of this blood protein, at least in alcoholics (33). Four to five weeks of abstinence are usually required for GGT levels to return to within normal range (33). The ability of this test to detect long-term heavy drinking in the recent past makes GGT useful for monitoring abstinence in recovering alcoholics. However, nonalcoholic liver disease also can increase GGT levels, increasing the likelihood of false-positive results.

Carbohydrate-deficient transferrin (CDT) is another blood protein that increases in concentration with heavy alcohol consumption (34). CDT values become elevated substantially earlier (1 to 2 weeks) in response to prolonged excessive drinking than conventional markers such as GGT (35). GGT and CDT are approximately equal in their ability to identify alcoholism. However, few conditions other than heavy drinking will elevate CDT levels, decreasing the probability of false positives (35). Disadvantages include lower sensitivity in women and adolescents, and the high cost of the laboratory analysis (33).

Mean corpuscular volume (MCV), an index of red blood cell size, increases with excessive alcohol intake after 4 to 8 weeks (33). The sensitivity of MCV is too low to justify its use as a single indicator (35). However, it has higher specificity compared with other tests. MCV can detect evidence of earlier drinking after a long period of abstinence. For this reason, it is a poor indicator of recovery among alcoholics who have stopped drinking (35).

Fatty acid ethyl esters (FAEEs) show promise as markers of maternal drinking. FAEEs are formed by the interaction of alcohol and natural fatty substances in the body. They have been detected in samples of meconium (i.e., the waste product of newborns). Some evidence suggests that analysis of FAEEs in meconium may indicate timing of prenatal alcohol exposure (34).


Screening for Alcohol Problems—A Commentary by Raynard Kington, M.D., Ph.D., Acting NIAAA Director, and Richard K. Fuller, M.D., Director, Division of Clinical and Prevention Research

National Alcohol Screening Day (NASD) is a nationwide, one-day event that provides free and confidential screening for alcohol problems. During NASD, screening-along with public education and referral to treatment, when necessary-occurs in a variety of health care and community settings, including college campuses and military bases. This Alert describes a number of questionnaires and medical tests that can be used in primary care settings to screen individuals who have or who are at risk for developing alcohol problems. We hope that the information provided here will encourage practitioners to make the screening and referral that are the centerpieces of NASD an ongoing part of their practice throughout the year. Given the impact of heavy drinking on overall health and the prevalence of patients in the primary care system who have an alcohol use problem, screening and referral should be considered part of sound clinical practice, rather than simply added patient services. More information on screening is available at the National Institute on Alcohol Abuse and Alcoholism Web site at http://www.niaaa.nih.gov/publications/instable.htm.


References

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Alcohol-Use Disorders Identification Test: A comparison between paper and pencil and computerized versions. Alcohol and Alcoholism 34(6):882–885, 1999. (32) Lessler, J.T.; Caspar, R.A.; Penne, A.; and Barker, P.R. Developing Computer Assisted Interviewing (CAI) for the National Household Survey on Drug Abuse. Journal of Drug Issues 30(1):9–34, 2000. (33) Allen, J.P., and Litten, R.Z. The role of laboratory tests in alcoholism treatment. Journal of Substance Abuse Treatment 20(1):81–85, 2001. (34) Bearer, C.F. Markers to detect drinking during pregnancy. Alcohol Research & Health 25(3):210–218, 2001. (35) Helander, A. Biological markers of alcohol use and abuse in theory and practice. In: Agarwal, D.P., and Seitz, H.K., eds. Alcohol in Health and Disease. New York: Marcel Dekker, 2001. pp. 177–205.


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Prepared: January 2002