The outcome variable was DSM-IV alcohol dependence and/or alcohol use disorder, here jointly referred to as “alcohol use disorder” (AUD; notice that these two diagnoses have been merged in DSM-5). AUD was assessed using computerized Norwegian version of World Health Organization’s Composite International Diagnostic Interview [37]. The Munich version that it is based on has an excellent test-retest reliability for AUD [38]. The interviewers attended a standardized CIDI training programme administered by teachers certified by the World Health Organization, and were closely followed-up individually during the whole data collection period. Exclusion criteria were not used. As specific outcomes, we study presence of a lifetime AUD diagnosis (failures to recall wave 1 AUD in wave 2 were corrected for), age of AUD onset, and presence of AUD within 5-year recency (i.e., current age minus the age at most recent episode was no more than five years).
