COGEND was designed as a community-based study of nicotine dependence. Subjects were recruited from Detroit, MI, and St. Louis, MO. More than 53,000 subjects were screened by telephone, more than 2,800 were personally interviewed, and over 2,700 donated blood samples for genetic studies (5, 6). To be recruited, subjects had to meet one of two ascertainment criteria. Nicotine dependent case subjects were current smokers who met criteria for nicotine dependence defined as having a current Fagerström Test for Nicotine Dependence (FTND) score of 4 or more (5). Non-dependent control subjects smoked at least 100 cigarettes in their lifetime with a lifetime maximum FTND score of 0 or 1. As part of the study design strategy, controls were over-sampled to have a lifetime maximum FTND score of 0, with 99.2% (910/917) of the European controls having a score of 0 and 82.1% (193/235) of the African American controls having a score of 0. There were no inclusionary or exclusionary criteria regarding alcohol or drug dependence. The present study includes 2597 unrelated, genotyped subjects from COGEND.
