To clarify discrepancies between results obtained using FTCD-based nicotine dependence and results obtained with CPD, we compared FTCD to CPD in a population-based sample. As part of recruitment to the COGEND study, subjects were randomly selected from the St. Louis region using the Missouri Family Registry, sent a letter, and called on the phone(3, 6). To evaluate the relationship between the phenotypes of CPD and the FTCD score, of the 28,658 subjects who completed the telephone screening, we selected the 14,343 subjects who had smoked at least 100 cigarettes in their lifetime and calculated the correlation between FTCD and CPD. We also calculated the polychoric correlations between the FTCD score components and CPD.
