A multidimensional assessment of the validity and utility of alcohol use disorder severity as determined by item response theory models.
BACKGROUND
The relative severity of the 11 DSM-IV alcohol use disorder (AUD) criteria are represented by their severity threshold scores, an item response theory (IRT) model parameter inversely proportional to their prevalence. These scores can be used to create a continuous severity measure comprising the total number of criteria endorsed, each weighted by its relative severity.


METHODS
This paper assesses the validity of the severity ranking of the 11 criteria and the overall severity score with respect to known AUD correlates, including alcohol consumption, psychological functioning, family history, antisociality, and early initiation of drinking, in a representative population sample of U.S. past-year drinkers (n=26,946).


RESULTS
The unadjusted mean values for all validating measures increased steadily with the severity threshold score, except that legal problems, the criterion with the highest score, was associated with lower values than expected. After adjusting for the total number of criteria endorsed, this direct relationship was no longer evident. The overall severity score was no more highly correlated with the validating measures than a simple count of criteria endorsed, nor did the two measures yield different risk curves. This reflects both within-criterion variation in severity and the fact that the number of criteria endorsed and their severity are so highly correlated that severity is essentially redundant.


CONCLUSIONS
Attempts to formulate a scalar measure of AUD will do as well by relying on simple counts of criteria or symptom items as by using scales weighted by IRT measures of severity.
Laboratory of Epidemiology and Biometry, Division of Intramural Clinical and Biological Research, National Institute on Alcohol Abuse and Alcoholism, National Institutes of Health, Bethesda, MD 20892, USA. ddawson@mail.nih.gov
Deborah A
DA
Dawson
Tulshi D
TD
Saha
Bridget F
BF
Grant
D000293:Adolescent; D000328:Adult; D000437:Alcoholism / Q000175:diagnosis*; D039721:Diagnostic and Statistical Manual of Mental Disorders; D006801:Humans; D015233:Models, Statistical; D011569:Psychiatric Status Rating Scales; D012720:Severity of Illness Index