Towards the characterization and validation of alcohol use disorder subtypes: integrating consumption and symptom data.
AIMS To replicate the finding that there is a single dimension trait in alcohol use disorders and to test whether the usual 5+ drinks for men and 4+ drinks for women and other measures of alcohol consumption help to improve alcohol use disorder criteria in a series of diverse patients from emergency departments (EDs) in four countries. DESIGN Cross-sectional surveys of patients aged 18 years and older that reflected consecutive arrival at the ED. The Composite International Diagnostic Interview Core was used to obtain a diagnosis of DSM-IV alcohol dependence and alcohol abuse; quantity and frequency of drinking and drunkenness as well as usual number of drinks consumed during the last year. SETTING Participants were 5195 injured and non-injured patients attending seven EDs in four countries: Argentina, Mexico, Poland and the United States (between 1995-2001). FINDINGS Using exploratory factor analyses alcohol use disorders can be described as a single, unidimensional continuum without any clear-cut distinction between the criteria for dependence and abuse in all sites. RESULTS from item response theory analyses showed that the current DSM-IV criteria tap people in the middle-upper end of the alcohol use disorder continuum. Alcohol consumption (amount and frequency of use) can be used in all EDs with the current DSM-IV diagnostic criteria to help tap the middle-lower part of this continuum. Even though some specific diagnostic criteria and some alcohol consumption variables showed differential item function across sites, test response curves were invariant for ED sites and their inclusion would not impact the final (total) performance of the diagnostic system. CONCLUSIONS DSM-IV abuse and dependence form a unidimensional continuum in ED patients regardless of country of survey. Alcohol consumption variables, if added, would help to tap patients with more moderate severity. The DSM diagnostic system for alcohol use disorders showed invariance and performed extremely well in these samples.