A Psychometric Study of the Drug Use Disorders Identification Test—Extended in a Norwegian Sample

Motivation is a widely used concept in substance use treatment, and is commonly seen as a premise for change during treatment. Different measures of motivation have been suggested. A relatively new instrument is the Drug Use Disorders Identification Test–Extended (DUDIT–E), developed in Sweden. This instrument has recently been introduced in Norway. The present study examined the Motivational Index of the Norwegian version of the Drug Use Disorders Identification Test-Extended (DUDIT–E). We tested whether the three-factor model (“Positive aspects of substance abuse”; “Negative aspects of substance abuse”; and “Treatment readiness”) suggested by previous studies could be replicated in a sample of Norwegian inpatients. Responses to the DUDIT–E were obtained from 105 patients admitted to inpatient substance abuse treatment in Northern Norway. Exploratory common factor analyses were used to compare the factor structure from the current sample with the Swedish sample of mainly detoxification patients and prison inmates. The current sample did not include prison inmates, and it consisted of more women than the Swedish sample. The samples did not differ according to age or substance dependency. The analyses suggested that six primary factors was the most efficient way of combining the item scores, and not 11 as in the Swedish sample. A second-order factor analysis found best support for a two-factor solution, and hence, did not replicate the previously suggested three-factor model either. Several regression analyses comparing the efficiency of the different ways of combining the DUDIT scores in primary or secondary factor scores indicated that the model involving six sum scores had best merit and should be explored further.