Table 2.

Study characteristics - adults

Study	Study design	Population	Follow-Up and Loss to Follow-Up	Definition: use neither product	Definition: exclusive smokeless tobacco (ST) user	Definition: exclusive smoker	Definition: dual use	How transitions calculated
Zhu et al. (2009)	• Tobacco Use Supplement to Current Population Survey 2002–2003 (TUS CPS)	• n = 15,056	• Follow-up one year later in 2003	Non-user = does not currently use either product, subgroups include never smokers and former smokers	ST user = currently uses chewing tobacco or snuff every day or some days	Cigarette smoker = has smoked ≥ 100 cigarettes in lifetime and currently smokes cigarettes every day or some days	Dual user = ST user + cigarette smoker	Percentages are weighted by census-derived survey weights, and stratified by gender, but not adjusted for other factors.
		• Males and females	• Only includes data for adults with baseline and follow-up information (excludes 1.9% of the sample with conflicting smoking information)
	• Nationally representative cross sectional survey with longitudinal component in some cycles	• ages 18+
		• Nationally representative
	• Household interviews at baseline in 2002 with follow-up in 2003 for some participants
Wetter et al. (2002)	• Secondary trial data from Working Well cancer prevention trial – University of Texas MD Anderson Cancer Center and worksites	• n = 1244 tobacco users	• Follow-up four years later	Non-user = has not smoked in past seven days and does not currently use smokeless tobacco	ST user = currently uses chewing tobacco, dip, or snuff	Cigarette smoker = has smoked ≥ 100 cigarettes in lifetime and has smoked in past seven days	Dual user = ST user + cigarette smoker	percentages are unadjusted
		• Males	• Only includes employees who remained at their baseline worksite four years later (62% of baseline sample)					adjusted odds ratios, for other analyses (not presented here)
	• Baseline in 1990	• Average age = 37.5 years
		• Reside in southeastern U.S.	• 52% of baseline dual users had follow up data, compared to 60% of smokers and 66% of ST users.
Haddock et al. (2001)	• Secondary data from Wilford Hall/University of Memphis and Minnesota Smoking Cessation Program	• n = 7865	• Mail-in follow-up one year after military basic training	Non-user = Never smoker + never ST user or never smoker + former ST user	ST user = uses smokeless tobacco at least once per day	Cigarette smoker at follow-up = has smoked at least a puff in last seven days	n/a	percentages are unadjusted
		• Males
	• Baseline questionnaire in August 1995	• Average age 19.8 years	• Follow-up takes place after an imposed tobacco ban	Never Smoker = has never smoked regularly (at least one cigarette per day)				adjusted odds ratios for other analyses (not presented here)
	• Treatment and control groups during a 6-week imposed tobacco ban in August 1996	• U.S. Air Force young adult male recruits who reported being never smokers at baseline	• 96% of smokers and 66% of nonsmokers had follow-up data from parent study
			• Follow-up excludes those who dropped out of basic training, completed training but dropped out of the survey, were deceased, or on assignment)