Because of the recruitment criteria used in the MSTF study, which differed from the KARE sample, there were only limited former smokers in the MSTF samples. Thus, we could not find an exactly same measure for both samples on smoking initiation phenotype. The age of onset in the MSTF sample is the age at which regular smoking was started, providing information on smoking initiation. Therefore, we used the age of onset phenotype in the replication study based on the available clinical information in MSTF. Also, the CPD in the MSTF sample is categorized CPD, as used in the KARE samples. In addition, we analyzed HSI and FTND for MSTF sample.
