A randomized controlled trial of a brief intervention for illicit drugs linked to the Alcohol, Smoking and Substance Involvement Screening Test (ASSIST) in clients recruited from primary health-care settings in four countries.
Humeniuk R., Ali R., Babor T. et al. Addiction: 2012, 107(5), p. 957–966.

Orchestrated by WHO, across all four countries this rare attempt at screening and brief intervention for problems arising from illegal drug use identified at front-line health care centres found modest reductions in use/risks, but there was a puzzling opposition between particularly positive results from Australia and seemingly negative ones from the USA.

Summary
Results of the featured study are also available in a research report previously analysed by Findings. Both this and the featured journal article are drawn on in the following account.

There is good evidence that brief interventions (usually one or two face-to-face counselling sessions) can reduce tobacco and alcohol use identified by screening tests in primary health care settings, particularly when they capitalise on the results of the test. However, there is only suggestive evidence of similar effects in respect of illicit drug use, only recently has a culturally neutral screening questionnaire for all psychoactive substances, including illicit drugs, been available for use in primary care, and most studies were conducted in the USA, UK or Australia, limiting the international generalisability of the findings.

To address these gaps the World Health Organization (WHO) developed the Alcohol, Smoking and Substance Involvement Screening Test (ASSIST). Through a series of interview questions it screens for problem or risky use of tobacco, alcohol, cannabis, cocaine, amphetamine-type stimulants, sedatives, hallucinogens, inhalants, opioids like heroin, and "other drugs". It first asks whether the patient has ever used these substances, then for those they have, how often in the past three months. Further questions in relation to each used substance ask about adverse consequences, urges to use, whether the individual has tried but failed to cut down, and whether others have shown concern over their substance use. Finally the patient is asked if they have injected drugs, if so when, and if recently, how often.

A risk score is calculated for each substance and categorised as low, moderate (harmful but not dependent use) or high (actually or probably dependent), in turn indicating whether no intervention is needed, a brief intervention to encourage the patient to cut back, or a brief intervention encouraging them to seek further and/or specialised treatment. ASSIST was primarily intended to identify patients at moderate risk who may otherwise go undetected and deteriorate.

To test this strategy, in 2003 to 2006, 845 potentially suitable patients were assessed by researchers and/or clinicians at health centres and other front-line medical care settings in Australia, India, the United States and Brazil. After completing the ASSIST interview, 731 adults were found to meet the study's criteria and agreed to join the study; another 51 refused. To join they had to have scored as at moderate risk due to their use of either cannabis, cocaine, amphetamine-type stimulants, or opioids, but not at high risk from any substance except tobacco. Two thirds of study participants were men and 72% were employed. They averaged about 31 years of age.

Following assessment patients were randomly allocated to wait for three months before intervention (the control group), or to participate (they all did) in a single brief advice session offered by the same clinician/researcher who had conducted the assessment, focused on the drug which posed the greatest risk to the patient and/or over which they were most concerned. In a motivational interviewing style, during this session patients were offered written feedback on their ASSIST scores and the implications (eg, health risks) were explored. They left with a self-help guide on reducing substance use. On average ASSIST screening took eight minutes and the brief intervention 14 minutes.

86% of the patients were followed up about three months later when the ASSIST test was re-applied. At issue was whether the risk scores of those who participated in the brief intervention three months before had decreased relative to the control group. How they might have scored at the follow-up was estimated for the patients who could not be re-assessed.