Background
Methods
Search strategy
I. Inclusion criteria | II. Exclusion criteria | ||
---|---|---|---|
a. | Original peer-reviewed articles from US studies published between January 1, 2000 and March 4, 2014 | a. | Studies from clinical trials, controlled cessation programs, and clinical studies or evaluations of smokeless tobacco cessation interventions without additional follow-up beyond the originally planned timeframe of the program |
b. | Articles include estimates of at least one transition between two points in time between a combination of the following tobacco use states: exclusive cigarette smoking, exclusive smokeless tobacco use, dual use of both products, and use of neither product. | b. | Studies that do not have data on smokeless transition behaviors |
c. | Non-human studies | ||
d. | Non-English language studies | ||
e. | Commentaries or non-empirical research | ||
f. | Studies published prior to 2000 | ||
g. | Studies on e-cigarettes as a “smokeless” product |
Data extraction
Results
Study selection
Study characteristics as sources of heterogeneity
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) |
Study | Study design | Population | Follow-up and loss to follow-up | Definition: use neither product | Definition: exclusive ST user | Definition: exclusive smoker | Definition: dual use | How transitions calculated |
---|---|---|---|---|---|---|---|---|
Tomar et al. (2003) | • The Teenage Attitudes and Practices Survey (TAPS-I and II), nationally representative cohort study, in 1988–1989 and 1993 | • n = 3,996 | • Four-year follow-up between 1989 and 1993 | Non-user = Not ST user + Not current smoker | ST user = self-identification as regular user of chewing tobacco or snuff | Current smoker = smoked ≥ 100 cigarettes in lifetime and smoked at least 1 day in 30 days preceding interview | Dual user = ST user + current smoker | percentages are weighted by survey weights |
• Young males | ||||||||
• Telephone interviews and self-administered questionnaires by mail (TAPS-I) or in-person contact (TAPS-II) | • Ages 11-19 | • 87.1% of baseline sample completed follow-up | adjusted odds ratios for other analyses (not presented here) | |||||
• Nationally representative | ||||||||
Severson et al. (2007) | • Cohort study conducted between 1994 and 1999 | • n = 2263 | • Two-year follow-up in 9th or 11th grade | Non-user = Non-smoker + Not ST user | ST user = any smokeless tobacco use in the past 30 days | Current smoker = WSI score is ≥ 1 | Dual user = ST user + cigarette smoker (only included at follow-up) | percentages are unadjusted |
• Young males | ||||||||
• Baseline survey completed once in 7th or 9th grade | • 7th and 9th-graders at baseline | Non-smoker = Has never smoked and Weekly Smoking Index (WSI) score is 0. WSI score averages answers to four questions about current smoking during past month | adjusted odds ratios for other analyses (not presented here) | |||||
• Evaluation of a randomized community intervention to prevent adolescent use | • Small rural communities in Oregon | |||||||
O’Hegarty et al. (2012) | • National Longitudinal Study of Adolescent Health (Add Health), a nationally representative school-based sample with Wave I conducted during the 1994–1995 school year | • n = 3284 | • Wave II conducted in 1996, approximately 1–2 years after Wave I (1994–1995) | ST user = reported using smokeless tobacco during the past 30 days | Current smoker = smoked on at least 1 of the past 30 days | Dual user = smoked on at least 1 of the past 30 days and used reported using smokeless during the past 30 days | ||
• Male and female | ||||||||
• Grades 7–11 when interviewed in Wave I | ||||||||
• Nationally representative sample |
Follow-up conditions differ by study
Tobacco use definitions varied across studies
Transitions between cigarette smoking and smokeless tobacco use states
Follow-up status | |||||
---|---|---|---|---|---|
Neither | Exclusive smokeless tobacco user | Exclusive smoker | Dual user | ||
Baseline
|
Neither
|
1 year follow-up
|
1 year follow-up
|
1 year follow-up
|
1 year follow-up
|
• 73.9%* male former smokers quit ≤1 yr [15] | • 1.7% males former smoker quit ≤1 yr (0.5 to 5.8) [15] | • 24.4% males former smoker quit ≤1 yr (17.1 to 33.6) [15] | • 0% males former smoker quit ≤1 yr [15] | ||
• 97%* males former smoker quit >1 yr [15] | • 0.3% males former smoker quit >1 yr (0.1 to 0.7) [15] | • 2.6% males former smoker quit >1 yr (1.9 to 3.6) [15] | • 0.1% males former smoker quit >1 yr (0.0 to 0.5) [15] | ||
• 96.7%* males never smoker [15] | • 0.7% males never smoker (0.5 to 1.1) [15] | • 2.5% males never smoker (1.7 to 3.8) [15] | • 0.1% males never smoker (0 to 0.3) [15] | ||
• 68.3%* females former smoker quit ≤1 yr [15] | • 0% females former smoker quit ≤1 yr [15] | • 31.7% females former smoker quit ≤1 yr (24.9 to 39.3) [15] | • 0% females former smoker quit ≤1 yr [15] | ||
• 97.1%* females former smoker quit >1 yr [15] | • 0.3% females former smoker quit >1 yr (0.1 to 0.6) [15] | • 2.9% females former smoker quit >1 yr (2.1 to 4.0) [15] | • 0% females never smoker [15] | ||
• 1.7% females never smoker (1.2 to 2.2) [15] | |||||
• 98.3%* females never smoker [15] | • 0% females never smoker [15] | • 12.9% of male never ST users [17] | |||
• 26.3% of male former ST users [17] | |||||
Exclusive smokeless tobacco user
|
1 year follow-up
|
1 year follow-up
|
1 year follow-up
|
1 year follow-up
| |
• 35.0% males (27.0 to 43.8) [15] | • 59.4% males (50.6 to 67.7) [15] | • 3.9% males (1.4 to 10.6) [15] | • 1.8% males (0.6 to 5.5) [15] | ||
• 44.1% females (22.2 to 68.6) [15] | • 52.7% females (27.4 to 76.7) [15] | • 3.2% females (0.2 to 31.5) [15] | • 0% females [15] | ||
• 26.6% males [17] | |||||
4 year follow-up
|
4 year follow-up
|
4 year follow-up
|
4 year follow-up
| ||
• 20.1% males [16] | • 76.6% of males [16] | • 0.9% males [16] | • 2.5% of males [16] | ||
Exclusive smoker
|
1 year follow-up
|
1 year follow-up
|
1 year follow-up
|
1 year follow-up
| |
• 11.3% males (8.7 to 14.2) [15] | • 0.3% males (0.1 to 0.8) [15] | • 86.2% males (83.1 to 88.9) [15] | • 2.2% males (1.4 to 3.5) [15] | ||
• 12.3% females (10.2 to 14.7) [15] | • 0% females [15] | • 87.6% female (85.2 to 89.7) [15] | • 0.1% female (0.0 to 0.2) [15] | ||
4 year follow-up
|
4 year follow-up
|
4 year follow-up
|
4 year follow-up
| ||
• 15.7% males [16] | • 1.4% males [16] | • 79.7% males [16] | • 3.2% males [16] | ||
Dual user
|
1 year follow-up
|
1 year follow-up
|
1 year follow-up
|
1 year follow-up
| |
• 13.1% males (4.9 to 30.7) [15] | • 4.9% males (0.9 to 23.1) [15] | • 37.0% males (23.2 to 53.4) [15] | • 45.0% males (29.7 to 61.3) [15] | ||
• 0% females [15] | • 0% females [15] | • 71.6% females (14.0 to 97.5) [15] | • 28.4% females (2.5 to 86.0) [15] | ||
4 year follow-up
|
4 year follow-up
|
4 year follow-up
|
4 year follow-up
| ||
• 11.3% of males [16] | • 17.4% of males [16] | • 27.0% males [16] | • 44.3% of males [16] |
Follow up status | |||||
---|---|---|---|---|---|
Neither | Exclusive smokeless tobacco user | Exclusive smoker | Dual user | ||
Baseline
|
Neither
|
2 year follow-up
|
2 year follow-up
|
2 year follow-up
|
2 year follow-up
|
• 71.5% males [20] | • 4.6% males [20] | 15.7% males [20] | • 8.3% males [20] | ||
4 year follow-up
|
4 year follow-up
|
4 year follow-up
|
4 year follow-up
| ||
• 82.2% males [19] | • 3.1% males [19] | • 13.5% males [19] | • 1.1% males [19] | ||
Exclusive smokeless tobacco user
|
2 year follow-up
|
2 year follow-up
|
2 year follow-up
|
2 year follow-up
| |
• 16.6% males [20] | • 26.2% males [20] | • 16.6% males [20] | • 40.7% males [20] | ||
4 year follow-up
|
4 year follow-up
|
4 year follow-up
|
4 year follow-up
| ||
• 15.2% males [19] | • 44.8% males [19] | • 25.5% males [19] | • 14.3% males [19] | ||
Exclusive smoker
|
1-2 year follow-up
|
1-2 year follow-up
|
1-2 year follow-up
|
1-2 year follow-up
| |
• 20.0% males and females combined [18] | • 1.6% males and females combined [18] | • 73.4% males and females combined [18] | • 5% males and females combined [18] | ||
2 year follow-up
|
2 year follow-up
|
2 year follow-up
|
2 year follow-up
| ||
• 25.6% males [20] | • 3.8% males [20] | • 46.8% males [20] | • 23.8% males [20] | ||
4 year follow-up
|
4 year follow-up
|
4 year follow-up
|
4 year follow-up
| ||
• 16.9% males [19] | • 0.8% males [19] | • 78.7% males [19] | • 3.6% of males [19] | ||
Dual user
|
1-2 year follow-up
|
1-2 year follow-up
|
1-2 year follow-up
|
1-2 year follow-up
| |
• 17.9% males and females combined [18] | • 8.5%* males and females combined [18] | • 36.6% males and females combined [18] | • 37% males and females combined [18] | ||
4 year follow-up
|
4 year follow-up
|
4 year follow-up
|
4 year follow-up
| ||
• 14.1% males [19] | • 34.2% males [19] | • 31.2% males [19] | • 20.4% males [19] |