Psychometric properties of a Norwegian adaption of the Barratt Impulsiveness Scale-11 in a sample of Parkinson patients, headache patients, and controls.

OBJECTIVE: To assess the psychometric properties of a Norwegian translation of the Barratt Impulsiveness Scale (BIS-11) for use in populations of headache, Parkinson's disease (PD), and healthy controls. MATERIALS AND METHODS: The BIS-11 was forward and backward translated by native speakers of both Norwegian and English to give Norwegian BIS-11 (Nor-BIS-11). A convenience sample (110 subjects) of healthy controls (47), PD patients (43), and chronic headache patients (20) (the latter two recruited from a Neurology outpatient clinic), were asked to complete the scale (a subset twice for test-retest). Exploratory and confirmatory factor analyses were done for a single-factor model, the original three-factor model and a two-factor model. Test-retest results were analyzed using the Bland-Altman approach. RESULTS: The Nor-BIS-11 scale showed good utility and acceptability as well as good test-retest reliability in this sample. Cronbach's α was .68, test-retest bias was -0.73, Cohen's δ = -.134, and limits of agreement were -11.48 to 10.01. The factor structure was found to fit better with a two-factor model than with the original model with three factors. The model fit indices indicated a moderate fit. CONCLUSIONS: The Nor-BIS-11 scale is acceptable and reliable to use in Parkinson's disease patients, chronic headache patients, and healthy controls. The results should be interpreted in a two-factor model but with caution due to low construct validity. External validity needs to be further tested.