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Trends in the Average Age of Quitting Among U.S. Adult Cigarette Smokers
Trends in the Average Age of Quitting Among U.S. Adult Cigarette Smokers Gillian L. Schauer, PhD, MPH,1,2 Ann M. Malarcher, PhD, MSPH,3 Kat J. Asman, MSPH4 Introduction: Quitting smoking at any age confers health benefits. However, studies have suggested that quitting by age 35 years leads to mortality rates similar to never smokers. This study assessed whether the mean and median ages of past-year quitting and prevalence of past-year quit attempts and successful quitting by age group changed over time. Methods: Data came from 113,599 adult cigarette smokers participating in the 1997–2012 National Health Interview Survey, an annual, cross-sectional household survey of U.S. adults aged Z18 years. Mean and median ages of past-year successful abstinence (quit 6–12 months) were computed. Orthogonal polynomial logistic regression models tested for trends in quit attempts and successful quitting. Data were analyzed in 2014.
Results: The average age of quitting (40.0 years in 1997–1998, 39.5 years in 2011–2012, p¼0.80) and median age of quitting (35.9 years in 1997–1998, 36.9 years in 2011–2012, p¼0.62) did not change over time. During 1997–2012, the percentage of smokers making a past-year quit attempt increased among those aged 25–34, 35–44, and 45–64 years; the percentage of smokers who reported quitting successfully increased among those aged 25–34 and 35–44 years (po0.001). Conclusions: Although the average age of quitting did not change over time, increases in past-year quit attempts and successful quitting occurred among adults aged 25–44 years. Proven populationlevel interventions—including price increases, mass media campaigns, comprehensive smoke-free policies, and health systems interventions—should be continued to further increase cessation, particularly among younger adults. (Am J Prev Med 2015;49(6):939–944) & 2015 American Journal of Preventive Medicine. All rights reserved.
Introduction
T
obacco use remains the primary cause of preventable death and disease in the U.S.1,2 Quitting cigarette smoking at any age confers health benefits.3,4 However, studies suggest that quitting by age 35 years leads to mortality rates similar to never smokers.5,6 Since the launch of the National Tobacco Control Program in 1999, state tobacco control programs have focused on proven population-based approaches that can reach all populations, including mass-reach From the 1Carter Consulting, Inc., Contractor to the Office on Smoking and Health, CDC, Atlanta, Georgia; 2Department of Behavioral Sciences and Health Education, Emory University, Atlanta, Georgia; 3Office on Smoking and Health, National Center for Chronic Disease Prevention and Health Promotion, CDC, Atlanta, Georgia; and 4Biostatistics and Epidemiology Division, Research Triangle International, Research Triangle Park, North Carolina Address correspondence to: Gillian L. Schauer, MPH, Carter Consulting, Inc., Office on Smoking and Health, CDC, 4770 Buford Highway, N.E., Mailstop F-79, Atlanta GA 30341. E-mail: [email protected]. 0749-3797/$36.00 http://dx.doi.org/10.1016/j.amepre.2015.06.028
& 2015 American Journal of Preventive Medicine. All rights reserved.
health communications campaigns, increased tobacco product pricing, smoke-free policies, and the promotion of evidence-based cessation treatments.7,8 One potential measure of the success of population-based tobacco control approaches is a reduction in the average age of quitting, or increases in quit attempts and successful cessation among younger smokers. Despite documented age-specific variations in cigarette smoking prevalence, data have not been published on whether the average age of quitting has changed since these widespread public health efforts began. Accordingly, this study assessed how the average age of quitting has changed over time among U.S. adults. Changes over time by age were also explored for two Healthy People 2020 measures9—quit attempts and successful quitting.
Methods Study Sample Data came from 113,599 past-year cigarette smokers aged Z18 years who participated in the 1997–2012 National Health Interview Am J Prev Med 2015;49(6):939–944
939
940
Schauer et al / Am J Prev Med 2015;49(6):939–944
Survey, a nationally representative, annual, cross-sectional household interview survey of non-institutionalized U.S. civilians.10
Measures Current smokers were defined as adults who had smoked Z100 cigarettes in their lifetime and smoked every day or some days at the time of survey. Past-year smokers were current smokers or those quit r1 year. Past-year quit attempts were assessed by asking current smokers: During the past 12 months, have you stopped smoking for more than 1 day because you were trying to quit smoking? Former smokers who quit during the past year were also included as having made a past-year quit attempt. Past-year successful quitting was defined as being quit 6 months to 1 year at the time of interview. People who were abstinent for o6 months were included in the denominator, but not the numerator. Age was categorized into five levels: 18–24, 25–34, 35–44, 45–64, and Z65 years.
Statistical Analysis Data were weighted for the probability of selection and nonresponse, and assessed in 2-year time increments to improve stability. The mean and median age of individuals who successfully quit cigarettes in the past year was computed. Past-year quit attempts and successful quitting were computed overall and by age group for each time increment, adjusting for sex; race/ethnicity; and in those aged Z25 years, education. Linear and quadratic trends were assessed via logistic regression using orthogonal polynomials.11 Percentage change was computed between the first and last time periods. Analyses were conducted in 2014 using SAScallable SUDAAN, version 9.2.
Results Both the mean (mean1997–1998, 40.6 years; mean2011–2012, 42.6 years; p-trendo0.0001) and median (median1997–1998 , 38.4 years; median2011–2012, 41.6 years; p-trendo0.0001)
age of past-year smokers increased from 1997–1998 to 2011–2012 (Figure 1). The distribution of changes in the age of past-year smokers mirrored a histogram of changes in the overall age of the U.S. population. The mean age of smokers with successful past-year cessation did not change significantly during 1997–2012, ranging from 38.1 years in 2003–2004 to 40.7 years in 2011–2012 (p-trend¼0.80, Table 1, Figure 1). Similarly, the median age of those who successfully quit did not change significantly during 1997–2012 (range, 33.3–36.9 years). Neither the mean nor median age of quitting differed significantly by sex (data not shown). Among smokers, the prevalence of making a past-year quit attempt (adjusted for sex, race/ethnicity, and education) increased in a nonlinear trend (from 48.4% in 1997–1998 to 51.7% in 2011–2012, plinear¼o0.0001, pquadratic¼0.008). By age, the percentage of smokers making a past-year quit attempt increased among those aged 25–34 (plinear¼0.001); 35–44 (plinearr0.0001, pquadratic¼0.004); and 45–64 (plinear¼0.0007) years (Table 1, Figure 1). Generally, there was an inverse relationship between age and past-year quit attempts, with a higher percentage of younger adults having made a past-year quit attempt than older adults. The adjusted prevalence of quitting successfully in the past year increased in a nonlinear trend from 5.2% in 1997–1998 to 6.4% in 2011–2012 (plinearr0.0001, pquadratic¼0.008). By age, the prevalence of successful past-year quits increased among those aged 25–34 (plinearr0.0001) and 35–44 (plinear¼0.002, pquadratic¼0.007) years (Table 1, Figure 1). When examining successful past-year quitting among only those who made a past-year quit attempt, similar increases were found among those aged 25–44 years. The prevalence of
Figure 1. Mean and median age (in years) for cigarette smokinga and past-year quitting,b and prevalence of past-year adult smokersc who made a quit attemptd and quit successfullye, by age group, NHIS, 1997–2012. Among all current smokers and smokers quit r1 year. Among all smokers quit from 6–12 months. c Includes adults who are current smokers or smokers quit r1 year. d A past-year quit attempt is defined as trying to quit cigarettes for Z1 day in the past year, adjusted for sex, race/ethnicity, and among those aged Z25 years, education. e Being quit from 6–12 months, adjusted for sex, race/ethnicity, and among those aged Z25 years, education. f p-trend o0.0001. g p-trend o0.001. NHIS, National Health Interview Survey. a
b
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December 2015
Table 1. Mean and Median Age of Those Who Report Recent Successful Quitting,a and Prevalence of Making a Past-Year Quit Attemptb or Successfully Quitting, by Age, NHIS, 2003–2012
Age
p-valued Linear, quadratic
40.7 (0.6)
1.7
0.8
36.9 (34.4, 39.2)
2.8
0.64
1999–2000
2001–2002
2003–2004
2005–2006
2007–2008
2009–2010
2011–2012
915
882
777
696
654
571
717
844
Mean age (SD)e
40.0 (0.7)
40.4 (0.7)
39.3 (0.7)
38.1 (0.7)
40.0 (0.7)
38.8 (0.8)
39.5 (0.9)
Median age (95% CI)e
35.9 (34.7, 37.9)
36.7 (34.4, 38.4)
35.7 (33.2, 37.9)
33.3 (31.5, 35.2)
36.5 (33.9, 39.4)
34.2 (32.0, 37.7)
33.9 (32.0, 37.7)
n
Prevalence of smokersf who made a past-year quit attemptb,f n
18,338
16,154
16,010
14,382
12,565
9,769
11,990
14,142
Overall
48.4 (47.5, 49.3)
49.4 (48.5, 50.4)
48.7 (47.7, 49.6)
48.4 (47.4, 49.4)
49.0 (47.8, 50.2)
50.6 (49.4, 51.7)
52.5 (51.3, 53.8)
51.7 (50.6, 52.8)
6.8
o0.0001, 0.008
18–24 years
57.7 (55.1, 60.2)
60.9 (58.5, 63.2)
58.7 (56.2, 61.1)
58.3 (55.4, 61.2)
56.1 (52.4, 59.6)
61.0 (57.4, 64.5)
61.9 (58.3, 65.3)
60.3 (56.8, 63.7)
4.5
0.17, 0.4
25–34 years
52.4 (50.4, 54.4)
53.2 (51.2, 55.2)
53.8 (51.9, 55.7)
53.5 (51.3, 55.7)
53.9 (51.6, 56.1)
54.2 (51.3, 57.1)
56.7 (54.4, 59.0)
56.5 (54.2, 58.7)
7.8
0.001, 0.43
35–44 years
46.6 (45.0, 48.3)
45.7 (43.9, 47.6)
45.7 (44.0, 47.4)
45.2 (43.3, 47.2)
48.1 (45.8, 50.4)
48.2 (45.5, 50.9)
52.9 (50.3, 55.4)
52.1 (49.4, 54.9)
11.9
o0.0001, 0.004
45–64 years
43.9 (42.4, 45.3)
45.6 (44.0, 47.3)
44.0 (42.4, 45.6)
43.7 (42.1, 45.2)
45.2 (43.4, 47.1)
47.1 (45.2, 49.1)
47.1 (45.2, 49.0)
46.7 (45.1, 48.4)
6.5
0.0007, 0.40
Z65 years
44.3 (41.8, 46.9)
44.5 (41.5, 47.5)
42.3 (39.6, 45.1)
44.9 (41.6, 48.1)
41.5 (38.1, 45.1)
40.1 (37.1, 45.0)
46.0 (42.3, 49.7)
44.7 (41.5, 47.9)
0.8
0.90, 0.13
g
Prevalence of smokers who quit in the past year n
a,f
18,383
16,195
16,047
14,426
12,596
9,793
12,004
14,155
Overall
5.2 (4.8, 5.6)
5.5 (5.1, 5.9)
5.1 (4.7, 5.5)
5.0 (4.6, 5.5)
5.3 (4.8, 5.7)
5.9 (5.3, 6.5)
6.0 (5.5, 6.6)
6.4 (5.9, 7.0)
23.3
o0.0001, 0.008
18–24 years
6.6 (5.4, 8.0)
7.1 (6.0, 8.4)
6.5 (5.3, 8.0)
7.6 (6.2, 9.3)
5.6 (4.4, 7.2)
7.3 (5.8, 9.1)
7.9 (6.1, 10.1)
7.0 (5.5, 9.0)
7.1
0.49, 0.81
25–34 years
5.9 (5.0, 6.9)
6.1 (5.3, 7.0)
6.2 (5.2, 7.3)
6.5 (5.5, 7.6)
6.7 (5.8, 7.9)
7.8 (6.4, 9.6)
8.2 (7.2, 9.4)
7.9 (6.7, 9.1)
33.3
o0.0001, 0.73
35–44 years
4.1 (3.5, 4.8)
4.1 (3.4, 4.8)
3.5 (3.0, 4.2)
4.0 (3.2, 4.8)
4.3 (3.5, 5.2)
4.7 (3.8, 5.8)
4.1 (3.2, 5.3)
6.4 (5.3, 7.8)
56.5
0.001, 0.007
45–64 years
4.6 (3.9, 5.4)
4.7 (4.0, 5.4)
4.3 (3.7, 5.2)
3.4 (2.8, 4.0)
4.7 (4.0, 5.5)
4.5 (3.8, 5.4)
4.8 (4.1, 5.6)
4.9 (4.2, 5.8)
7.4
0.31, 0.04
65Z years
7.6 (6.2, 9.3)
8.8 (7.2, 10.7)
6.8 (5.2, 8.7)
6.8 (5.2, 8.7)
5.9 (4.5, 7.7)
5.9 (4.5, 7.8)
6.5 (5.1, 8.2)
7.4 (5.7, 9.4)
3.3
0.14, 0.07
Schauer et al / Am J Prev Med 2015;49(6):939–944
% Changec
1997–1998
(continued on next page)
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Table 1. Mean and Median Age of Those Who Report Recent Successful Quitting,a and Prevalence of Making a Past-Year Quit Attemptb or Successfully Quitting, by Age, NHIS, 2003–2012 (continued)
1997–1998
1999–2000
2001–2002
2003–2004
2005–2006
2007–2008
2009–2010
2011–2012
% Changec
p-valued Linear, quadratic
Prevalence of smokersg quit in the past yeara, among those who made a past-year quit attemptb,f n
8,846
7,903
7,747
6,897
6,087
4,895
6,342
7,364
Overall
10.7 (9.9, 11.6)
11.1 (10.3, 11.9)
10.5 (9.7, 11.4)
10.4 (9.6, 11.3)
10.8 (9.9, 11.7)
11.6 (10.5, 12.8)
11.5 (10.6, 12.6)
12.4 (11.5, 13.5)
15.70
0.005, 0.04
18–24 years
11.4 (9.4, 13.9)
11.7 (9.9, 13.8)
11.2 (9.1, 13.6)
13.1 (10.8, 15.9)
10.1 (8.0, 12.7)
11.9 (9.5, 14.7)
12.7 (9.9, 16.2)
11.6 (9.1, 14.7)
1.90
0.75, 0.97
25–34 years
11.4 (9.7, 13.2)
11.4 (9.9, 13.1)
11.5 (9.8, 13.5)
12.1 (10.3, 14.2)
12.6 (10.8, 14.7)
14.4 (11.8, 17.4)
14.5 (12.7, 16.5)
14.0 (12.1, 16.1)
23.10
0.0007, 0.89
35–44 years
8.9 (7.6, 10.4)
8.9 (7.6, 10.5)
7.8 (6.5, 9.2)
8.7 (7.1, 10.6)
8.9 (7.3, 10.8)
9.7 (7.8, 12.0)
7.9 (6.2, 9.9)
12.4 (10.3, 14.8)
39.60
0.04, 0.03
45–64 years
10.5 (9.0, 12.2)
10.3 (8.9, 11.8)
9.9 (8.4, 11.7)
7.8 (6.6, 9.1)
10.4 (9.0, 12.1)
9.6 (8.0, 11.5)
10.3 (8.8, 12.1)
10.6 (9.0, 12.3)
0.6
0.82, 0.07
Z65 years
17.1 (14.2, 20.5)
19.8 (16.5, 23.5)
15.9 (12.6, 19.9)
15.2 (11.8, 19.3)
14.2 (10.8, 18.4)
14.5 (10.9, 19.1)
14.2 (11.1, 17.9)
16.5 (13.0, 20.8)
3.4
0.12, 0.17
Note: Values represent weighted % (95% CI) unless otherwise indicated. a Quitting is defined as being quit from 6 to 12 months. b Making a past-year quit attempt is defined as trying to quit for Z1 day in the past 12 months. c Percent change for 1997–1998 versus 2011–2012. d p-value computed from trend tests. e Mean and median age are computed among individuals who quit in the past year, and were quit from 6 to 12 months at the time of the survey. f For ages 18–24 years, analyses are adjusted for sex and race. For ages Z25 years, analyses are adjusted for sex, race, and education. g Smokers are defined as those who currently smoked or were quit o1 year at the time of the survey. NHIS, National Health Interview Survey.
Schauer et al / Am J Prev Med 2015;49(6):939–944
Age
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Schauer et al / Am J Prev Med 2015;49(6):939–944
successful quits among those who tried to make a pastyear quit attempt was highest each year among those aged Z65 years.
Discussion This study suggests that the mean and median age at which U.S. adults reported successful past-year quitting did not change during 1997–2012. However, the population of smokers appears to be aging over time, so the finding that the average age of quitting has not increased may suggest progress. Additionally, the proportion of smokers who reported past-year quit attempts and successful quitting increased among adults aged 25–44 years. Because of the aging population, this suggests it will become increasingly important to track population quit attempts and recent quitting success by age as opposed to only tracking the average or median age of quitting. While past-year quit attempts and successful quitting have increased among those aged 25–44 years, no change was observed among younger adults aged 18–24 years. Although prevalence of quit attempts by age group was the highest among younger adults, they are less likely to use effective cessation treatments than older adults.12 Young adulthood represents a critical time for intervention to prevent establishment of more-regular smoking patterns.13–18 As the Affordable Care Act increases healthcare coverage among younger adults,19 opportunities for health professionals to provide evidence-based cessation interventions may increase. Continued implementation of coordinated, comprehensive tobacco control interventions has the potential to increase cessation among all age groups.8,20 Though past-year quit attempts increased among smokers aged 45–64 years, the proportion in that group that reported successfully quitting did not change. Zhu et al.21 in 2012 found no consistent increasing trends in quitting among the overall population of U.S. smokers. While these data suggest increases in recent quitting among individuals aged 25 to 44 years, more research is needed to understand why recent successful quitting is not increasing among older age groups. Data suggest that smokers who quit during the ages of 45–54 or 55–64 years still gain an average of 6 and 4 years of life, respectively5; accordingly, efforts to help individuals in this age group quit, and quit earlier, are warranted. Interestingly, among those who made a past-year quit attempt, those aged Z65 years were the most successful at each time period. These quits may be motivated by smoking-related disease.
Limitations This study is subject to limitations. First, data are crosssectional; long-term patterns of quit attempts or successful December 2015
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quitting at an individual level could not be assessed. Second, all analyses focused on cigarette smoking and did not include other tobacco products, including electronic nicotine delivery devices. Finally, National Health Interview Survey sampling does not include institutionalized populations or persons in the military, which limits generalizability.
Conclusions Increasing the prevalence of successful quitting among all age groups, especially among young adults, is critical to reducing overall smoking-attributable morbidity and mortality. Proven population-level interventions that increase quitting should be continued. The findings and conclusions in this report are those of the authors and do not necessarily represent the official position of CDC. No financial disclosures were reported by the authors of this paper.
References 1. USDHHS. The Health Consequences of Smoking—50 Years of Progress. A Report of the Surgeon General. Atlanta, GA: USDHHS, CDC, National Center for Chronic Disease Prevention and Health Promotion, Office on Smoking and Health; 2014. 2. CDC. Smoking-attributable mortality, years of potential life lost, and productivity losses—United States, 2000-2004. MMWR Morb Mortal Wkly Rep. 2008;57:1226–1228. 3. USDHHS. The Health Consequences of Smoking: A report for the Surgeon General. Washington, DC: USDHHS, CDC; 2004. 4. USDHHS. The Health Benefits of Smoking Cessation: A Report of the Surgeon General. Atlanta, GA: USDHHS, CDC, Center for Chronic Disease Prevention and Health Promotion, Office on Smoknig and Health; 1990. 5. Jha P, Ramasundarahettige C, Landsman V, et al. 21st-century hazards of smoking and benefits of cessation in the United States. N Engl J Med. 2013;368(4):341–350. http://dx.doi.org/10.1056/NEJMsa1211128. 6. Doll R, Peto R, Boreham J, Sutherland I. Mortality in relation to smoking: 50 years’ observations on male British doctors. BMJ. 2004;328(7455):1519. http://dx.doi.org/10.1136/bmj.38142.554479.AE. 7. CDC. Guide to Community Preventive Services. Reducing tobacco use and secondhand smoke exposure: comprehensive tobacco control programs. www.thecommunityguide.org/tobacco/comprehen sive.html. Published 2014. Accessed October 21, 2014. 8. CDC. Best Practices for Comprehensive Tobacco Control Programs— 2014. Atlanta, GA: USDHHS, CDC, National Center for Chronic Disease Prevention and Health Promotion, Office on Smoking and Health; 2014. 9. USDHHS, Office of Disease Prevention and Health Promotion. Healthy People 2020 Summary Objectives: Tobacco Use. http://www.healthy people.gov/2020/topics-objectives/topic/tobacco-use/objectives. Accessed July 7, 2013. 10. USDHHS, CDC, National Center for Health Statistics. Design and Estimation for the National Health Interview Survey, 2006-2015: Data Evaluation and Methods Research. Hyattsville, MD: USDHHS; 2014. 11. CDC. Conducting Trend Analyses of YRBS data. www.cdc.gov/health yyouth/yrbs/pdf/yrbs_conducting_trend_analyses.pdf. Published 2014. Accessed July 7, 2014.
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12. CDC. Quitting Smoking Among Adults—United States, 2001-2010. MMWR Morb Mortal Wkly Rep. 2011;60(44):1513–1519. 13. Juon HS, Ensminger ME, Sydnor KD. A longitudinal study of developmental trajectories to young adult cigarette smoking. Drug Alcohol Depend. 2002;66(3):303–314. http://dx.doi.org/10.1016/S03768716(02)00008-X. 14. Klein EG, Bernat DH, Lenk KM, Forster JL. Nondaily smoking patterns in young adulthood. Addict Behav. 2013;38(7):2267–2272. http://dx. doi.org/10.1016/j.addbeh.2013.03.005. 15. Orlando M, Tucker JS, Ellickson PL, Klein DJ. Developmental trajectories of cigarette smoking and their correlates from early adolescence to young adulthood. J Consult Clin Psychol. 2004;72(3): 400–410. http://dx.doi.org/10.1037/0022-006X.72.3.400. 16. Brook JS, Lee JY, Brown EN, Finch SJ. Comorbid trajectories of tobacco and marijuana use as related to psychological outcomes. Subst Abus. 2012;33(2):156–167. http://dx.doi.org/10.1080/08897077.2011.640202. 17. Chassin L, Presson CC, Pitts SC, Sherman SJ. The natural history of cigarette smoking from adolescence to adulthood in a midwestern community sample: multiple trajectories and their psychosocial
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correlates. Health Psychol. 2000;19(3):223–231. http://dx.doi.org/ 10.1037/0278-6133.19.3.223. Riggs NR, Chou CP, Li C, Pentz MA. Adolescent to emerging adulthood smoking trajectories: when do smoking trajectories diverge, and do they predict early adulthood nicotine dependence? Nicotine Tob Res. 2007; 9(11):1147–1154. http://dx.doi.org/10.1080/14622200701648359. Sommers BD. USDHHS. Number of young adults gaining insurance due to the Affordable Care Act now tops 3 million. Office of the Assistant Secretary for Planning and Evaluation, USDHHS. http://aspe.hhs.gov/aspe/gaininginsurance/rb.cfm. Published June 2012. USDHHS. Preventing Tobacco Use Among Youth and Young Adults: A Report of the Surgeon General. Atlanta, GA: USDHHS, CDC, National Center for Chronic Disease Prevention and Health Promotion, Office on Smoking and Health; 2012. Zhu SH, Lee M, Zhuang YL, Gamst A, Wolfson T. Interventions to increase smoking cessation at the population level: how much progress has been made in the last two decades? Tob Control. 2012;21(2): 110–118. http://dx.doi.org/10.1136/tobaccocontrol-2011-050371.
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Results: The average age of quitting (40.0 years in 1997–1998, 39.5 years in 2011–2012, p¼0.80) and median age of quitting (35.9 years in 1997–1998, 36.9 years in 2011–2012, p¼0.62) did not change over time. During 1997–2012, the percentage of smokers making a past-year quit attempt increased among those aged 25–34, 35–44, and 45–64 years; the percentage of smokers who reported quitting successfully increased among those aged 25–34 and 35–44 years (po0.001). Conclusions: Although the average age of quitting did not change over time, increases in past-year quit attempts and successful quitting occurred among adults aged 25–44 years. Proven populationlevel interventions—including price increases, mass media campaigns, comprehensive smoke-free policies, and health systems interventions—should be continued to further increase cessation, particularly among younger adults. (Am J Prev Med 2015;49(6):939–944) & 2015 American Journal of Preventive Medicine. All rights reserved.
Introduction
T
obacco use remains the primary cause of preventable death and disease in the U.S.1,2 Quitting cigarette smoking at any age confers health benefits.3,4 However, studies suggest that quitting by age 35 years leads to mortality rates similar to never smokers.5,6 Since the launch of the National Tobacco Control Program in 1999, state tobacco control programs have focused on proven population-based approaches that can reach all populations, including mass-reach From the 1Carter Consulting, Inc., Contractor to the Office on Smoking and Health, CDC, Atlanta, Georgia; 2Department of Behavioral Sciences and Health Education, Emory University, Atlanta, Georgia; 3Office on Smoking and Health, National Center for Chronic Disease Prevention and Health Promotion, CDC, Atlanta, Georgia; and 4Biostatistics and Epidemiology Division, Research Triangle International, Research Triangle Park, North Carolina Address correspondence to: Gillian L. Schauer, MPH, Carter Consulting, Inc., Office on Smoking and Health, CDC, 4770 Buford Highway, N.E., Mailstop F-79, Atlanta GA 30341. E-mail: [email protected]. 0749-3797/$36.00 http://dx.doi.org/10.1016/j.amepre.2015.06.028
& 2015 American Journal of Preventive Medicine. All rights reserved.
health communications campaigns, increased tobacco product pricing, smoke-free policies, and the promotion of evidence-based cessation treatments.7,8 One potential measure of the success of population-based tobacco control approaches is a reduction in the average age of quitting, or increases in quit attempts and successful cessation among younger smokers. Despite documented age-specific variations in cigarette smoking prevalence, data have not been published on whether the average age of quitting has changed since these widespread public health efforts began. Accordingly, this study assessed how the average age of quitting has changed over time among U.S. adults. Changes over time by age were also explored for two Healthy People 2020 measures9—quit attempts and successful quitting.
Methods Study Sample Data came from 113,599 past-year cigarette smokers aged Z18 years who participated in the 1997–2012 National Health Interview Am J Prev Med 2015;49(6):939–944
939
940
Schauer et al / Am J Prev Med 2015;49(6):939–944
Survey, a nationally representative, annual, cross-sectional household interview survey of non-institutionalized U.S. civilians.10
Measures Current smokers were defined as adults who had smoked Z100 cigarettes in their lifetime and smoked every day or some days at the time of survey. Past-year smokers were current smokers or those quit r1 year. Past-year quit attempts were assessed by asking current smokers: During the past 12 months, have you stopped smoking for more than 1 day because you were trying to quit smoking? Former smokers who quit during the past year were also included as having made a past-year quit attempt. Past-year successful quitting was defined as being quit 6 months to 1 year at the time of interview. People who were abstinent for o6 months were included in the denominator, but not the numerator. Age was categorized into five levels: 18–24, 25–34, 35–44, 45–64, and Z65 years.
Statistical Analysis Data were weighted for the probability of selection and nonresponse, and assessed in 2-year time increments to improve stability. The mean and median age of individuals who successfully quit cigarettes in the past year was computed. Past-year quit attempts and successful quitting were computed overall and by age group for each time increment, adjusting for sex; race/ethnicity; and in those aged Z25 years, education. Linear and quadratic trends were assessed via logistic regression using orthogonal polynomials.11 Percentage change was computed between the first and last time periods. Analyses were conducted in 2014 using SAScallable SUDAAN, version 9.2.
Results Both the mean (mean1997–1998, 40.6 years; mean2011–2012, 42.6 years; p-trendo0.0001) and median (median1997–1998 , 38.4 years; median2011–2012, 41.6 years; p-trendo0.0001)
age of past-year smokers increased from 1997–1998 to 2011–2012 (Figure 1). The distribution of changes in the age of past-year smokers mirrored a histogram of changes in the overall age of the U.S. population. The mean age of smokers with successful past-year cessation did not change significantly during 1997–2012, ranging from 38.1 years in 2003–2004 to 40.7 years in 2011–2012 (p-trend¼0.80, Table 1, Figure 1). Similarly, the median age of those who successfully quit did not change significantly during 1997–2012 (range, 33.3–36.9 years). Neither the mean nor median age of quitting differed significantly by sex (data not shown). Among smokers, the prevalence of making a past-year quit attempt (adjusted for sex, race/ethnicity, and education) increased in a nonlinear trend (from 48.4% in 1997–1998 to 51.7% in 2011–2012, plinear¼o0.0001, pquadratic¼0.008). By age, the percentage of smokers making a past-year quit attempt increased among those aged 25–34 (plinear¼0.001); 35–44 (plinearr0.0001, pquadratic¼0.004); and 45–64 (plinear¼0.0007) years (Table 1, Figure 1). Generally, there was an inverse relationship between age and past-year quit attempts, with a higher percentage of younger adults having made a past-year quit attempt than older adults. The adjusted prevalence of quitting successfully in the past year increased in a nonlinear trend from 5.2% in 1997–1998 to 6.4% in 2011–2012 (plinearr0.0001, pquadratic¼0.008). By age, the prevalence of successful past-year quits increased among those aged 25–34 (plinearr0.0001) and 35–44 (plinear¼0.002, pquadratic¼0.007) years (Table 1, Figure 1). When examining successful past-year quitting among only those who made a past-year quit attempt, similar increases were found among those aged 25–44 years. The prevalence of
Figure 1. Mean and median age (in years) for cigarette smokinga and past-year quitting,b and prevalence of past-year adult smokersc who made a quit attemptd and quit successfullye, by age group, NHIS, 1997–2012. Among all current smokers and smokers quit r1 year. Among all smokers quit from 6–12 months. c Includes adults who are current smokers or smokers quit r1 year. d A past-year quit attempt is defined as trying to quit cigarettes for Z1 day in the past year, adjusted for sex, race/ethnicity, and among those aged Z25 years, education. e Being quit from 6–12 months, adjusted for sex, race/ethnicity, and among those aged Z25 years, education. f p-trend o0.0001. g p-trend o0.001. NHIS, National Health Interview Survey. a
b
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Table 1. Mean and Median Age of Those Who Report Recent Successful Quitting,a and Prevalence of Making a Past-Year Quit Attemptb or Successfully Quitting, by Age, NHIS, 2003–2012
Age
p-valued Linear, quadratic
40.7 (0.6)
1.7
0.8
36.9 (34.4, 39.2)
2.8
0.64
1999–2000
2001–2002
2003–2004
2005–2006
2007–2008
2009–2010
2011–2012
915
882
777
696
654
571
717
844
Mean age (SD)e
40.0 (0.7)
40.4 (0.7)
39.3 (0.7)
38.1 (0.7)
40.0 (0.7)
38.8 (0.8)
39.5 (0.9)
Median age (95% CI)e
35.9 (34.7, 37.9)
36.7 (34.4, 38.4)
35.7 (33.2, 37.9)
33.3 (31.5, 35.2)
36.5 (33.9, 39.4)
34.2 (32.0, 37.7)
33.9 (32.0, 37.7)
n
Prevalence of smokersf who made a past-year quit attemptb,f n
18,338
16,154
16,010
14,382
12,565
9,769
11,990
14,142
Overall
48.4 (47.5, 49.3)
49.4 (48.5, 50.4)
48.7 (47.7, 49.6)
48.4 (47.4, 49.4)
49.0 (47.8, 50.2)
50.6 (49.4, 51.7)
52.5 (51.3, 53.8)
51.7 (50.6, 52.8)
6.8
o0.0001, 0.008
18–24 years
57.7 (55.1, 60.2)
60.9 (58.5, 63.2)
58.7 (56.2, 61.1)
58.3 (55.4, 61.2)
56.1 (52.4, 59.6)
61.0 (57.4, 64.5)
61.9 (58.3, 65.3)
60.3 (56.8, 63.7)
4.5
0.17, 0.4
25–34 years
52.4 (50.4, 54.4)
53.2 (51.2, 55.2)
53.8 (51.9, 55.7)
53.5 (51.3, 55.7)
53.9 (51.6, 56.1)
54.2 (51.3, 57.1)
56.7 (54.4, 59.0)
56.5 (54.2, 58.7)
7.8
0.001, 0.43
35–44 years
46.6 (45.0, 48.3)
45.7 (43.9, 47.6)
45.7 (44.0, 47.4)
45.2 (43.3, 47.2)
48.1 (45.8, 50.4)
48.2 (45.5, 50.9)
52.9 (50.3, 55.4)
52.1 (49.4, 54.9)
11.9
o0.0001, 0.004
45–64 years
43.9 (42.4, 45.3)
45.6 (44.0, 47.3)
44.0 (42.4, 45.6)
43.7 (42.1, 45.2)
45.2 (43.4, 47.1)
47.1 (45.2, 49.1)
47.1 (45.2, 49.0)
46.7 (45.1, 48.4)
6.5
0.0007, 0.40
Z65 years
44.3 (41.8, 46.9)
44.5 (41.5, 47.5)
42.3 (39.6, 45.1)
44.9 (41.6, 48.1)
41.5 (38.1, 45.1)
40.1 (37.1, 45.0)
46.0 (42.3, 49.7)
44.7 (41.5, 47.9)
0.8
0.90, 0.13
g
Prevalence of smokers who quit in the past year n
a,f
18,383
16,195
16,047
14,426
12,596
9,793
12,004
14,155
Overall
5.2 (4.8, 5.6)
5.5 (5.1, 5.9)
5.1 (4.7, 5.5)
5.0 (4.6, 5.5)
5.3 (4.8, 5.7)
5.9 (5.3, 6.5)
6.0 (5.5, 6.6)
6.4 (5.9, 7.0)
23.3
o0.0001, 0.008
18–24 years
6.6 (5.4, 8.0)
7.1 (6.0, 8.4)
6.5 (5.3, 8.0)
7.6 (6.2, 9.3)
5.6 (4.4, 7.2)
7.3 (5.8, 9.1)
7.9 (6.1, 10.1)
7.0 (5.5, 9.0)
7.1
0.49, 0.81
25–34 years
5.9 (5.0, 6.9)
6.1 (5.3, 7.0)
6.2 (5.2, 7.3)
6.5 (5.5, 7.6)
6.7 (5.8, 7.9)
7.8 (6.4, 9.6)
8.2 (7.2, 9.4)
7.9 (6.7, 9.1)
33.3
o0.0001, 0.73
35–44 years
4.1 (3.5, 4.8)
4.1 (3.4, 4.8)
3.5 (3.0, 4.2)
4.0 (3.2, 4.8)
4.3 (3.5, 5.2)
4.7 (3.8, 5.8)
4.1 (3.2, 5.3)
6.4 (5.3, 7.8)
56.5
0.001, 0.007
45–64 years
4.6 (3.9, 5.4)
4.7 (4.0, 5.4)
4.3 (3.7, 5.2)
3.4 (2.8, 4.0)
4.7 (4.0, 5.5)
4.5 (3.8, 5.4)
4.8 (4.1, 5.6)
4.9 (4.2, 5.8)
7.4
0.31, 0.04
65Z years
7.6 (6.2, 9.3)
8.8 (7.2, 10.7)
6.8 (5.2, 8.7)
6.8 (5.2, 8.7)
5.9 (4.5, 7.7)
5.9 (4.5, 7.8)
6.5 (5.1, 8.2)
7.4 (5.7, 9.4)
3.3
0.14, 0.07
Schauer et al / Am J Prev Med 2015;49(6):939–944
% Changec
1997–1998
(continued on next page)
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942
Table 1. Mean and Median Age of Those Who Report Recent Successful Quitting,a and Prevalence of Making a Past-Year Quit Attemptb or Successfully Quitting, by Age, NHIS, 2003–2012 (continued)
1997–1998
1999–2000
2001–2002
2003–2004
2005–2006
2007–2008
2009–2010
2011–2012
% Changec
p-valued Linear, quadratic
Prevalence of smokersg quit in the past yeara, among those who made a past-year quit attemptb,f n
8,846
7,903
7,747
6,897
6,087
4,895
6,342
7,364
Overall
10.7 (9.9, 11.6)
11.1 (10.3, 11.9)
10.5 (9.7, 11.4)
10.4 (9.6, 11.3)
10.8 (9.9, 11.7)
11.6 (10.5, 12.8)
11.5 (10.6, 12.6)
12.4 (11.5, 13.5)
15.70
0.005, 0.04
18–24 years
11.4 (9.4, 13.9)
11.7 (9.9, 13.8)
11.2 (9.1, 13.6)
13.1 (10.8, 15.9)
10.1 (8.0, 12.7)
11.9 (9.5, 14.7)
12.7 (9.9, 16.2)
11.6 (9.1, 14.7)
1.90
0.75, 0.97
25–34 years
11.4 (9.7, 13.2)
11.4 (9.9, 13.1)
11.5 (9.8, 13.5)
12.1 (10.3, 14.2)
12.6 (10.8, 14.7)
14.4 (11.8, 17.4)
14.5 (12.7, 16.5)
14.0 (12.1, 16.1)
23.10
0.0007, 0.89
35–44 years
8.9 (7.6, 10.4)
8.9 (7.6, 10.5)
7.8 (6.5, 9.2)
8.7 (7.1, 10.6)
8.9 (7.3, 10.8)
9.7 (7.8, 12.0)
7.9 (6.2, 9.9)
12.4 (10.3, 14.8)
39.60
0.04, 0.03
45–64 years
10.5 (9.0, 12.2)
10.3 (8.9, 11.8)
9.9 (8.4, 11.7)
7.8 (6.6, 9.1)
10.4 (9.0, 12.1)
9.6 (8.0, 11.5)
10.3 (8.8, 12.1)
10.6 (9.0, 12.3)
0.6
0.82, 0.07
Z65 years
17.1 (14.2, 20.5)
19.8 (16.5, 23.5)
15.9 (12.6, 19.9)
15.2 (11.8, 19.3)
14.2 (10.8, 18.4)
14.5 (10.9, 19.1)
14.2 (11.1, 17.9)
16.5 (13.0, 20.8)
3.4
0.12, 0.17
Note: Values represent weighted % (95% CI) unless otherwise indicated. a Quitting is defined as being quit from 6 to 12 months. b Making a past-year quit attempt is defined as trying to quit for Z1 day in the past 12 months. c Percent change for 1997–1998 versus 2011–2012. d p-value computed from trend tests. e Mean and median age are computed among individuals who quit in the past year, and were quit from 6 to 12 months at the time of the survey. f For ages 18–24 years, analyses are adjusted for sex and race. For ages Z25 years, analyses are adjusted for sex, race, and education. g Smokers are defined as those who currently smoked or were quit o1 year at the time of the survey. NHIS, National Health Interview Survey.
Schauer et al / Am J Prev Med 2015;49(6):939–944
Age
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Schauer et al / Am J Prev Med 2015;49(6):939–944
successful quits among those who tried to make a pastyear quit attempt was highest each year among those aged Z65 years.
Discussion This study suggests that the mean and median age at which U.S. adults reported successful past-year quitting did not change during 1997–2012. However, the population of smokers appears to be aging over time, so the finding that the average age of quitting has not increased may suggest progress. Additionally, the proportion of smokers who reported past-year quit attempts and successful quitting increased among adults aged 25–44 years. Because of the aging population, this suggests it will become increasingly important to track population quit attempts and recent quitting success by age as opposed to only tracking the average or median age of quitting. While past-year quit attempts and successful quitting have increased among those aged 25–44 years, no change was observed among younger adults aged 18–24 years. Although prevalence of quit attempts by age group was the highest among younger adults, they are less likely to use effective cessation treatments than older adults.12 Young adulthood represents a critical time for intervention to prevent establishment of more-regular smoking patterns.13–18 As the Affordable Care Act increases healthcare coverage among younger adults,19 opportunities for health professionals to provide evidence-based cessation interventions may increase. Continued implementation of coordinated, comprehensive tobacco control interventions has the potential to increase cessation among all age groups.8,20 Though past-year quit attempts increased among smokers aged 45–64 years, the proportion in that group that reported successfully quitting did not change. Zhu et al.21 in 2012 found no consistent increasing trends in quitting among the overall population of U.S. smokers. While these data suggest increases in recent quitting among individuals aged 25 to 44 years, more research is needed to understand why recent successful quitting is not increasing among older age groups. Data suggest that smokers who quit during the ages of 45–54 or 55–64 years still gain an average of 6 and 4 years of life, respectively5; accordingly, efforts to help individuals in this age group quit, and quit earlier, are warranted. Interestingly, among those who made a past-year quit attempt, those aged Z65 years were the most successful at each time period. These quits may be motivated by smoking-related disease.
Limitations This study is subject to limitations. First, data are crosssectional; long-term patterns of quit attempts or successful December 2015
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quitting at an individual level could not be assessed. Second, all analyses focused on cigarette smoking and did not include other tobacco products, including electronic nicotine delivery devices. Finally, National Health Interview Survey sampling does not include institutionalized populations or persons in the military, which limits generalizability.
Conclusions Increasing the prevalence of successful quitting among all age groups, especially among young adults, is critical to reducing overall smoking-attributable morbidity and mortality. Proven population-level interventions that increase quitting should be continued. The findings and conclusions in this report are those of the authors and do not necessarily represent the official position of CDC. No financial disclosures were reported by the authors of this paper.
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