Clinical data were collected using a computer-assisted telephone diagnostic interview (CATI) based on an adaptation of the Semi-Structured Assessment for the Genetics of Alcoholism (SSAGA; Bucholz et al., 1994; Hesselbrock et al., 1999) and the Composite International Diagnostic Interview (CIDI; Cottler et al., 1991)for telephone administration, and also a mailed self-report questionnaire. The tobacco section for the CATI was derived from the CIDI (Cottler et al., 1991), and incorporated FTND (Heatherton et al., 1991), DSM-IIIR (APA, 1987) and DSM-IV (APA, 1994) assessments of nicotine dependence. It also included a detailed history of the first use of cigarettes and other tobacco products, the quantity and frequency of use for current or most recent (if ex-smoker) and heaviest period of use, supplemental items concerning attempts at cessation, and DSM-IV symptoms of nicotine withdrawal. Information on other comorbid psychiatric disorders such as major depression and anxiety disorders, and conduct and anti-social personality disorder were also elicited by the CATI. Interviewers were mostly selected from highly trained panels of interviewers at Queensland Institute of Medical Research and the University of Helsinki that included nurses or graduates in psychology or a related field.
