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A mixed methods approach to improve the measurement of Alcohol-Induced Blackouts: ABOM-2.

BACKGROUND
Alcohol-induced blackouts describe memory loss resulting from alcohol consumption. Approximately half of college students report experiencing a blackout in their lifetime. Blackouts are associated with an increased risk for negative consequences, including serious injury. Research has documented two types of blackouts, en bloc (EB) and fragmentary (FB). However, research is limited by lack of a validated measure that differentiates between these two forms of blackout. This study used a mixed methods approach to improve the assessment of FB and EB among young adults. We specifically sought to improve the existing Alcohol-Induced Blackout Measure (ABOM), which was derived from a relatively small pool of items that did not distinguish FB from EB.


METHODS
Study 1 used three rounds of cognitive interviewing with college students (N=31) to refine existing assessment items. Nineteen refined blackout items were retained for Study 2. Study 2 used face validity, factor analysis, item response theory, and external validation analyses to test the two-factor blackout model among heavy-drinking college students (N=474) and to develop and validate a new blackout measure (ABOM-2).


RESULTS
Iterative factor analyses demonstrated that the items were well-represented by correlated EB and FB factors, consistent with our hypothesis. External validation analyses demonstrated convergent and discriminant validity, and there was preliminary evidence for the two factors having differential predictive validity (e.g., FB correlated with enhancement drinking motives, while EB correlated with coping and conformity motives).


CONCLUSIONS
The Alcohol-Induced Blackout Measure-2 (ABOM-2) improves measurement of blackout experiences among college students and will facilitate examination of EB and FB as differential predictors of alcohol-related outcomes in future studies.