IRT-based alcohol use severity scores can be estimated for each individual based on the number and the respective severity signals of endorsed symptoms. These IRT-based scores as well as total symptom counts were used to examine the DSM-IV diagnostic system. The severity of AUDs was compared across diagnostic orphans and persons with abuse or dependence diagnoses. Exploratory analyses were conducted to examine alternative means of categorizing AUDs. These exploratory analyses were aimed at eliminating the incongruities of diagnostic orphans and persons diagnosed with alcohol abuse who appear to have more severe AUDs.
