Alcohol screening in general practices using the AUDIT: how many response categories are necessary?

The Alcohol Use Disorders Identification Test (AUDIT) is a common screening instrument. This study analyses if response categories of the AUDIT might be dichotomized without affecting the psychometric properties of the questionnaire.

Participants between 18 and 65 years were recruited from general practices in two northern German cities. In total, 10,803 screenings were conducted (refusal rate: 5.9%). For those who were screened positive, the Munich-Composite International Diagnostic Interview (M-CIDI) was used for identification of 12-month Alcohol Use Disorders and at-risk consumption (exceeding 20/30 g per day). Abstinent subjects and screening positives without diagnostic interview were excluded from the analysis, leaving a sample of 7,112 subjects. ROC-Curves were calculated separately for each item in order to identify an optimal cut-off value. Finally, a version of the AUDIT based on dichotomized items was compared to the original version and its short-form, the AUDIT version based on three questions dealing with consumption AUDIT-C.

As an optimal cut-off value for items on consumption, drinking at least once a week, having more than 1-2 drinks per occasion, and drinking 6 or more drinks in one sitting at least once a month were identified. For all questions on alcohol-related problems or dependence symptoms, having 'ever occurred' differed best between subjects with and without Alcohol Use Disorders or at-risk consumption. Sensitivity and specificity of the dichotomized version of the AUDIT did not differ from the original version, and both full versions performed superior compared to the AUDIT-C.

Data indicate that the AUDIT response categories may be dichotomized without affecting its validity.