PROBLEM DRINKING IN A GENERAL-PRACTICE POPULATION - THE CONSTRUCTION OF AN INTERVAL SCALE FOR SEVERITY OF PROBLEM DRINKING

The main aim of this article is to describe the construction of an int erval scale measuring the severity of problem drinking among patients of general practitioners. A questionnaire, including the existing scre ening instruments CAGE, SMAST, a shortened version of the SAAST and so me additional items on alcohol-related problems, was given to three ca tegories of patients: those who, according to the general practitioner , were not problem drinkers (Group 1), those who perhaps were (Group 2 ) and those who were known by the general practitioner to be problem d rinkers (Group 3). According to the Classical Test Theory, the three e xisting screening instruments and the combination of all questions for m a reliable scale. Advanced scaling techniques were applied to select the best items for the construction of an interval scale. These analy ses showed that 18 of the 28 questions in the complete screening list fitted in a unidimensional Rasch scale. These questions can be used to estimate the severity of problem drinking. For research purposes an i nterval scale is attractive, since no information is lost by dichotomi zation. Such a scale enables the level of problem drinking to be speci fied at which correlations with other factors, whether as a cause or a s an effect, can be found. The scale could also be a help to general p ractitioners for referral decisions. In more specialized settings it c an be used to assign patients to various treatments.