These results should be interpreted in the context of two potentially important methodological limitations. First, we identified subjects with alcohol use disorder from medical, legal, and pharmacy records. While this method does not require respondent cooperation or accurate recall and reporting, it could produce both false negative and false positive diagnoses. Given that the population prevalence of alcohol use disorder in this sample is much lower than estimates from epidemiologic surveys (10, 50), including one from neighboring Norway (which estimated lifetime prevalence for alcohol use disorder at 13.2% and 5.2% in men and women, respectively) (51), false negative diagnoses are surely much more common than false positive ones. Compared with those identified in epidemiologic surveys, the cases of alcohol use disorder that we studied are likely to be more severe and to be associated with more prominent alcohol-related social and medical consequences. The best available validation for our definition of illness is the high rates of concordance for registration observed across our different ascertainment methods (52).
