Logistic regression as implemented in Stata Version 9 (36) was used to assess the association between relapse and the Rasch modeled nicotine withdrawal sensitivity score. The Family Based Association Test (FBAT) (37) as implemented within the GeneticsBase package from Bioconductor (38) of the R programming language (39) was used to test for association between OPRM1 SNPs in the pedigrees between the nicotine withdrawal sensitivity score and 18 candidate SNPs. We considered P-values <0.05 to represent nominal statistical significance.
