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Screening for alcohol problems

Defining at-risk and problem drinking

Canada's low-risk drinking guidelines (Canadian Centre on Substance Abuse [CCSA], 2013) define at-risk or problem drinking as consuming more than 15 drinks per week for men and more than 10 drinks per week for women. 

Standard drinks

The low-risk drinking guidelines define a standard drink as:

  • 43mL (1.5 oz.) spirit (40% alcohol)
  • 142 mL (5 oz.) table wine (12% alcohol)
  • 341 mL (12 oz.) regular beer (5% alcohol)
  • 85 mL (3 oz.) fortified wine (18% alcohol).

Recognizing alcohol problems

Primary care providers can use various strategies to better detect alcohol problems:

  • Incorporate questions about alcohol use into routine lifestyle questions for all patients.
  • Use the single-item screener, AUDIT-C, AUDIT-10 (manual and questionnaire) or other validated screening questionnaire for all patients who drink alcohol.
  • Investigate alcohol as a possible cause of many common problems seen in primary care.
  • Order appropriate laboratory tests if alcohol use is suspected to be a problem.

Screening tools

Single-item screener

The U.S. National Institute on Alcohol Abuse and Alcoholism (2005) recommends the single-item screener as an excellent option for detecting heavy drinking because it is easy to memorize and incorporate into practice.

The single question:

  • Males: "How many times in the past year have you had five or more drinks in a day?"
  • Females: "How many times in the past year have you had four or more drinks in a day?"

Once or more is a positive response that indicates a need for further assessment.

Researchers recommend different cut-off points for the single-item screener:

  • Using once or more as the cut-off for a positive test for at-risk drinking, the test has both a sensitivity and specificity of about 80 per cent (Dawson et al., 2010).
  • Using a higher cut-off, with more than once as a positive response, this screening test had a sensitivity of 88 per cent and a specificity of 67 per cent for a current alcohol use disorder (Smith et al., 2009).

Depending on how common alcohol problems are in your clinic, the single-item screener may generate quite a few false positives. For example, a person who has had only two episodes of heavy drinking in the past year is unlikely to have a significant alcohol problem. As with other screening tests, patients who screen positive should be fully assessed before at-risk drinking or an alcohol use disorder is diagnosed.


The three-question AUDIT-C is simple to administer and has a similar sensitivity and specificity as the single-item screener, but it is difficult to memorize because of the complex scoring system.


The AUDIT-10 (manual and questionnaire) is longer than the AUDIT-C, but has excellent sensitivity and specificity. A cut-off score of 8 or more indicates unhealthy drinking. Newer research suggests that the cut-off be lower for women (Johnson et al., 2007; Levola & Aalto, 2015; Neumann et al., 2004).

A note about the CAGE

The four-item CAGE is easy to memorize and identifies most patients with an alcohol use disorder, but it misses many patients with at-risk drinking (Bradley et al., 1998).

Initial laboratory tests

Blood tests can help to identify excessive alcohol use and possible liver damage. These tests have a low sensitivity and therefore should be used only to confirm suspected alcohol problems, not as a sole screening test.

Blood tests can also be used to monitor changes in patients' alcohol consumption. Informing patients of their test results gives them concrete evidence of their progress.

Gamma glutamyl transferase (GGT)

An elevated gamma glutamyl transferase (GGT) level may indicate high alcohol consumption. The GGT test is 30 to 50 percent sensitive for detecting consumption of four or more drinks per day (Rosman, 1992; Sharpe, 2001).

However, GGT is also elevated in people with non-alcoholic liver disease, diabetes or obesity, and who use certain medications (e.g., phenytoin). GGT has a half-life of two to four weeks, so if GGT is elevated because of drinking, the level will decrease by half after two to four weeks of abstinence.

Complete blood count (CBC)

Mean cell volume (MCV), an index of red blood cell size, increases with heavy drinking. This test is less sensitive than GGT. MCV is also elevated in people with folate or vitamin B12 deficiency, non-alcoholic liver disease or hypothyroidism, and who take certain medications (e.g., phenytoin).

MCV's half-life is three months, so if MCV is elevated because of drinking, the level will decrease by half after three months of abstinence.

Taking an alcohol use history

  • Ask patients about their typical weekly consumption and maximum daily consumption:

"On average, how many days per week do you drink alcohol?"

"On a typical day when you drink, how many drinks do you have?"

"What is the maximum number of drinks you have had on any one day during the past three months?"

  • Convert responses to standard drinks.
  • If patients give vague responses or you think they may be under-reporting their consumption, try these strategies:
    • Ask about alcohol consumption in the past week or the past day.
    • Ask about the number and size of bottles purchased per week.
    • Present patients with a wide range of consumption.
  • Let patients know that you won't be shocked by heavy consumption:

"Would you say you drink one or two beers per night, or 10 or 12 beers per night?"

  • Provide a medical or social excuse for drinking:

"Many people have a drink or two to help them get to sleep. Do you ever have a drink before bed?"

"Do you ever have a glass of wine with dinner? How about at Christmas or New Years?"

  • Document current alcohol use on every patient's chart, including:
    • the number of drinks per week
    • the maximum drinks on any day in the past three months.

Medical conditions that may indicate alcohol problems

Patients with the following symptoms should be screened for alcohol problems:

  • musculoskeletal symptoms: trauma
  • gastrointestinal symptoms: gastritis, esophagitis, fatty liver, elevated transaminases
  • cardiovascular symptoms: hypertension
  • psychiatric symptoms: depression, anxiety, insomnia, social and family dysfunction.

Be aware that patients tend not to count heavy drinking episodes in their estimate of average weekly consumption.

Managing alcohol problems: Online course:

  • consists of five self-directed modules that cover identification, assessment and treatment
  • includes case scenarios, interactive review questions, end of module quizzes
  • accredited event: College of Family Physicians of Canada and Royal College of Physicians & Surgeons of Canada

Developed for health care providers by the Centre for Addiction and Mental Health.

Download the flyer.