Consistent with previous genetic studies (Saccone et al., 2009; Yang et al, 2005), we created a variable measuring maximum number of drinks in a 24-hour period (Maxdrinks) during the period of lifetime heaviest drinking. Maxdrinks ranged from 1–40. This was assessed using the Alcohol Use Disorders and Associated Disabilities Interview Schedule (AUDADIS (Grant et al., 1995; Hasin et al., 2007)) adapted for the present study. The AUDADIS measure for lifetime maximum quantity consumed has very good inter-rater reliability (intraclass correlation coefficients [ICC] of 0.70 (Hasin et al., 2007)).
