|Year : 2016 | Volume
| Issue : 4 | Page : 370-376
Effectiveness of cognitive behavior therapy in tobacco cessation at a dental setting: A hospital-based randomized controlled trial
A Leena Selvamary, MB Aswath Narayanan, Jayanthi Doss, SG Ramesh Kumar
Department of Public Health Dentistry, Tamil Nadu Government Dental College and Hospital, Chennai, Tamil Nadu, India
|Date of Web Publication||15-Dec-2016|
A Leena Selvamary
No. 7A, Tower 2, Lotus Pond, Vijay Shanti Apartments, No 46, IT Expressway, Thaiyur, B-Village, Kelambakkam, Chengalpattu, Kancheepuram - 603 103, Tamil Nadu
Source of Support: None, Conflict of Interest: None
Clinical trial registration CTRI/2011/10/002041
Introduction: Tobacco use continues to be the leading global cause of preventable death. Dental health professionals play a significant role in the intervention of the tobacco-related epidemic. Aim: The aim of this study was to compare the effectiveness of health education (HE) alone and HE with cognitive behavior therapy (CBT) at a dental tertiary referral unit of South India. Materials and Methods: Self-reported quit attempt was assessed and the sample size was estimated at 194. Tobacco users who met the inclusion criteria were randomly assigned to one of the two groups - HE only and HE with CBT. Age, sex, socioeconomic status, form of tobacco usage, alcohol usage, addiction and stage of motivation, knowledge, attitude, and behavior regarding tobacco use, and ill effects were assessed at baseline. Follow-up was for 6 months (2nd, 6th, 12th, and 24th weeks) to assess reduced use, quit attempt, point prevalence abstinence, continuous abstinence, lapse, relapse, and attrition rates in each visit. The self-reported quit rates were validated using the standardized cotinine test. Pearson's Chi-square test was used to determine the effectiveness of intervention. Results: Continuous abstinence was significantly high in CBT. Reduced use and point prevalence abstinence were significantly higher in HE. Quit attempt in both the groups was equal showing no statistical significance. Attrition was significantly higher in HE compared to CBT. Conclusion: CBT plays a vital role in achieving continuous abstinence, overcoming social factors, and reducing lapse among the tobacco users.
Keywords: Cognitive behavior therapy, health education, tobacco cessation
|How to cite this article:|
Selvamary A L, Aswath Narayanan M B, Doss J, Ramesh Kumar S G. Effectiveness of cognitive behavior therapy in tobacco cessation at a dental setting: A hospital-based randomized controlled trial. J Indian Assoc Public Health Dent 2016;14:370-6
|How to cite this URL:|
Selvamary A L, Aswath Narayanan M B, Doss J, Ramesh Kumar S G. Effectiveness of cognitive behavior therapy in tobacco cessation at a dental setting: A hospital-based randomized controlled trial. J Indian Assoc Public Health Dent [serial online] 2016 [cited 2020 Aug 11];14:370-6. Available from: http://www.jiaphd.org/text.asp?2016/14/4/370/195845
| Introduction|| |
The harmful effects of tobacco are proven ever since the 1950s., Tobacco use kills nearly 6 million people and causes half a trillion dollar of economic damage every year. As the second most populous country in the world, India's share of the global burden of tobacco-induced disease and death is substantial. India is the 2nd largest producer and 3rd largest consumer of tobacco worldwide. With 274.9 million tobacco users in the country and the usage prevailing among the people as a part of tradition and custom, India's tobacco problem is more complex with the consumption pattern either largely influenced by the socioeconomic backgrounds or dictated by the cultural diversity.
When a person reduces or relinquishes tobacco usage, he/she experiences an unpleasant withdrawal syndrome  which accounts to spontaneous reinstatement of the habit. Moreover, other factors influencing tobacco use include: Sociodemographic factors (socioeconomic status, developmental challenges of adolescence, gender, and race/ethnicity), environmental factors (acceptability and availability of tobacco products, interpersonal variables, perceived environmental variables), behavioral factors (academic achievement, problem behaviors, influence of peer groups, participation in activities, and behavioral skills), personal factors (knowledge of the long-term health consequences of using tobacco, functional meanings of tobacco use, subjective expected utility of tobacco use, variables related to self-esteem, and personality), and the current behavior relative to tobacco use (intentions to smoke and smoking status). Hence, effective implementation of tobacco control strategies necessitates intersectoral cooperation.
The Indian government in accordance with the World Health Organization has been taking measures to curtail the usage through various tobacco control initiatives such as raising taxes, alternative crop for farmers, cultivating the cash crop in South-East Asia, and enforcing bans on tobacco advertising, promotion, and sponsorship. One among these is strengthening the health systems in treating tobacco dependence by engaging health-care professionals in tobacco control. Among the health-care professionals, a reasonable position would be for dentists to raise awareness of the impact of tobacco use on oral and general health, as tobacco usage can be identified at the earliest during screening.
A wide range of pharmacologic and nonpharmacologic treatments have been successfully used to assist individuals in quitting tobacco. The most effective approach to smoking cessation appears to result from the combination of these modalities. The pharmacological interventions include nicotine replacement therapy and antidepressants. Nonpharmacologic interventions to support smoking cessation can be successfully delivered through clinical approaches and through broader public health approaches. Certain interventions such as self-help programs, telephone counseling, health education (HE), and cognitive behavioral therapy (CBT) are amenable to either individual delivery in the clinical setting or broad dissemination to geographic communities or workplaces.
Systematic reviews have suggested that physician advice for tobacco cessation and individual behavior therapy are cost-effective modalities that achieve cessation of the addictive habit.,, Webb et al. concluded that CBT was effective in tobacco cessation of African-American smokers. Carr and Ebbert in a systematic review of tobacco cessation in a dental setting have stated that there are few studies worldwide that have been effectively conducted at the dental setting. There were no previous studies registered in the Clinical Trials Registry of India to compare the effectiveness of CBT in tobacco cessation done among the Indian population and at a dental setting. The current study was thus designed as first of its kind to compare the effectiveness of HE alone and CBT as two treatment modalities for tobacco cessation in a dental hospital setting and among the South Indian tobacco users.
| Materials and Methods|| |
A randomized controlled trial was designed to compare the effectiveness of HE and CBT in a dental hospital setting. The study was conducted at the tobacco cessation center of the selected dental hospital, during 2011–2012, for 10 months.
Ethical clearance was obtained from the Institutional Ethical Committee, and the trial was registered in the Clinical Trials Registry of India (CTRI/2011/10/002041). The study procedure was explained to the patients, and written informed consent was obtained.
A pilot study was done in a random sample of thirty current tobacco users attending the tobacco cessation center of the selected dental tertiary referral center. A pretested customized questionnaire was administered to the participants to assess the knowledge, attitude, and behavior of the various types of tobacco (Cronbach's α = 0.980). The participants were randomly assigned into two groups based on the intervention that was provided, i.e., HE alone , and a combination of HE and CBT., Quit attempt was assessed after a week and cotinine test was performed to validate quitting. The self report quit attempt was 20% and 46.7% for HE alone and combination of HE and CBT respectively. Evaluation by cotinine test validated the quit status as 13.3% and 40% for HE alone and a combination of HE and CBT, respectively. The sample size was estimated at 194 (15% excess of sample size to compensate for attrition).
The sample comprised current tobacco users who have been defined as continuous users of any form or combination of tobacco until the day of recruitment. Among 519 individuals referred for tobacco cessation program during the period of recruitment, 194 participants met the inclusion criteria. Those hard of hearing or with speech difficulty, mentally challenged, or under treatment for psychiatric disorders were excluded from the study. Those participants prediagnosed to have tobacco-induced oral or systemic diseases were also excluded from the study.
All the individuals enrolled received HE therapy, and later 94 randomly selected individuals (computer-generated randomization) who were assigned to CBT received CBT.
The pro forma consisted of the demographic data, medical and dental history, tobacco use status, and a pretested customized questionnaire consisting of 56 questions to assess the knowledge, attitude, and behavior of tobacco use. Twenty-one questions assessed the knowledge, 29 assessed the attitude and behavior, and six questions assessed the cost analysis and decision balance which motivates the patient to quit. Age, sex, socioeconomic status, form of tobacco usage, alcohol usage, addiction, the stage of motivation, and the contemplation ladder  were assessed at baseline. Confidence rating scale was used to assess the importance and confidence of the patients to quit tobacco usage. Fagerstrom questionnaire for smoking  and smokeless forms  was used to assess the addiction of the individual.
At the 1st visit, baseline data were collected, questionnaire was administered, and HE was provided. Eight custom-made posters and a video developed in local language (Tamil) and in English explained the epidemiology of tobacco-related deaths, chemical contents, various forms of tobacco, Cigarette and other Tobacco Products Act in India, the process of addiction, its ill effects on health, benefits on quitting the habit, and the instructions to do on quitting. A pamphlet consisting of various harmful agents in the cigarettes and the written instructions to do on quitting tobacco usage was handed over to all participants.
Participants were then randomly allocated based on computer-generated randomization into the 2nd intervention group (CBT). The participants were blinded regarding the intervention group they were being allocated. At the 2nd visit (1 week after recruitment), the randomized participants who were allocated to the CBT group received CBT and participants in the HE group were motivated and stoppage was reinforced. The intervention in CBT constituted (1) provision of cognition (by self-identification of the cause of initiation of the habit, identification of the conditioned daily routines, and learning to reduce and cope with negative mood or urge to smoke associated with nicotine withdrawal) (2) provision of counseling to achieve behavioral change (by breaking the routine, managing the temptation to use tobacco, and the various day-to-day stresses which enhance the usage) (3) motivational interviewing to understand and accept the reality (through usage of questions, insight was provided regarding importance to quit tobacco usage), and (4) relapse prevention strategies were taught and asked to be followed.
During each follow-up after the intervention, a timeline follow-back calendar was utilized to assess the self-reported outcome variables, namely, reduced use, quit attempt (24 h point prevalence abstinence), point prevalence abstinence (7-day point prevalence abstinence), continuous abstinence (28-day/4-week point prevalence abstinence), lapse (slip between abstinence), and relapse. Self-reported abstinence was validated using cotinine test at the end of 6 months. Participants were followed up for 6 months (a total of five sessions at 1st, 2nd, 6th, 12th, and 24th weeks from the 1st visit), and follow-up reminder was done by both postcards and phone calls.
Data analysis was done using IBM SPSS Inc. Released 2009. PASW Statistics for Windows, Version 18.0. Chicago: SPSS Inc. At baseline, descriptive analysis assessed the prevalence of variables that influenced the intervention outcomes (age, sex, socioeconomic status, form of tobacco usage, alcohol usage, addiction, the stage of motivation, and preintervention knowledge scores). Mann–Whitney U-test was performed to assess the baseline difference in preintervention knowledge scores and addiction scores between the intervention groups. At the end of the trial, the outcome variables were assessed using Pearson's Chi-square test to determine the effectiveness of intervention. Pearson's Chi-square and Kendall's tau-b tests were employed to analyze the influence that baseline confounding factors may have on the outcome.
| Results|| |
During the period of recruitment, 519 (males = 140, females = 379) patients reported for tobacco cessation counseling, of whom 194 met the inclusion criteria (HE: n = 100, CBT: n = 94). The mean age was 34.91 years in HE and 35.64 years in CBT. Males (95%) reported more than females (5%) during the period of recruitment. Fifty percent of the population were in lower-upper class of socioeconomic status. Those using smoking form were more than the smokeless form or both the forms of usage. Forty-four percent of the tobacco users were alcoholics with 39% of them reported family history of tobacco usage. Ninety percent of the sample were in contemplation stage of motivation at recruitment. Knowledge of the participants at the baseline was poor with a mean score of 7.53 (maximum score = 21). Age, sex, socioeconomic status, form of tobacco usage, alcohol usage, and the stage of motivation were compared between the groups at baseline using Pearson's Chi-square and no significant difference was found. The baseline addiction and knowledge scores were assessed using Mann–Whitney U-test and was found to be similar between the intervention groups [Table 1]. Intention-to-treat analysis was done, and the dropouts in the follow-up sessions were considered to continue tobacco usage [Figure 1].
|Table 1: Baseline assessment of addiction and knowledge score by Mann–Whitney U-test|
Click here to view
Reduced use was significantly higher in HE (75%) than in CBT (54.3%) (P = 0.002). Quit attempts were similar in both the groups (HE: 94%, CBT: 98.9%) with no statistical difference. Point prevalence abstinence was significantly higher in HE (HE: 73%, CBT: 71.3%) (P = 0.006). Continuous abstinence was significantly high in CBT (HE: 30%, CBT: 68.1%) (P = 0.000). Percentage of lapse was significantly higher in HE (HE: 49%, CBT: 35%, P = 0.035). The rate of relapse (5%) was similar between groups with no significant difference. The rate of attrition was high (73.2%) with reasons being migration to other places during the last session review, change of address, and change of phone number [Table 2].
Evaluation at the 2nd session (1 week after intervention) revealed reduced use significantly high in HE, and quit attempt and point prevalence abstinence significantly high in CBT. At the 3rd session (6 weeks after intervention), quit attempt, point prevalence abstinence, and lapse were significantly higher in HE. CBT had significant higher continuous abstinence. Relapse was more in HE. During the 4th session (12 weeks after intervention), quit attempt and lapse were more in HE whereas point prevalence abstinence and continuous abstinence were more in CBT. During the 5th session (24 weeks after intervention), continuous abstinence was significantly high in CBT. The cotinine test validated the true quitters (cross assessment of self-reported quit and negative for tobacco usage). The true quitters were significantly higher in CBT [Table 3] and [Table 4].
There was no significant difference in the prevalence of outcome variables between groups when considering the influence of the baseline variables such as age, sex, stages of motivation, various social strata, forms of tobacco usage, alcohol usage, and family history of tobacco usage. There was a significant but a weak positive correlation of occurrence of lapse in HE with the knowledge scores [Table 5].
| Discussion|| |
In scientific and medical circles, a conceptual shift has occurred in considering tobacco addiction similar to alcohol and other drug addiction as a disease rather than a habit., Addiction is the result of heavy drug use that changes the structure and function of the brain, making cessation difficult. The paradigm that addiction is a “disease of the brain” has been provoked, and the International Classification of Diseases-10 has categorized tobacco addiction as a mental and behavioral disorder. Tobacco addiction has embedded behavioral and social aspects that are important parts of the disorder itself. Therefore, the most effective treatment approaches will include biological, behavioral, and social contexts. Behavioral change is inherently an unstable and unsteady process with frequent lapses and relapses. Hence, it is imperative that support should be provided at all stages of change from precontemplation to maintenance to prevent relapse.
HE is “consciously constructed opportunities for learning involving some form of communication designed to improve health literacy, including improving knowledge and developing life skills, which are conducive to individual and community health.” A systematic review by Lancaster and Stead estimated that a brief advice intervention by a physician can increase quitting by a further 1%–3% when unassisted quit rate was assumed to be 2%–3%. At the end of 6 months after HE as intervention, the abstinence from smoking was 15% which was higher than previous studies., Tobacco users intervened by CBT had higher decrease in the Fagerstrom's addiction scores, yet there was no statistical difference considering HE as equally effective.
CBT in the current study had 98.9% of any quit attempt and 26.6% of continuous abstinence in 6 months. The outcome was higher than previous studies by Pieterse et al., Carpenter et al., Nohlert et al., Lough et al., and lower than studies by Steven et al., Walsh et al., Polanska et al., Molyneux et al., Hanioka et al., and similar to studies by Robinson et al., Raupach et al., and Webb et al. Attrition was greater compared to previous studies by Nohlert et al, and lower than the study by Lough et al.
With 274.9 million current tobacco users in the country and only 9% having tried counseling for tobacco cessation, it becomes imperative to address this health hazard and stir up strong measures toward damage control. Various environmental and social factors such as peer influence, job-related stresses, family issues, and smoking environment cause lapse and relapse to tobacco usage. HE though an effective method to help start to quit tobacco usage, CBT helps overcoming these social stigmas associated with tobacco use initiation and relapse prevention. Consensus has been obtained in the 2nd European workshop on tobacco use prevention and cessation to integrate tobacco cessation activities among the oral health professionals. International and national associations for oral health professionals and all oral health professionals can act as advocates to promote population, community, and individual initiatives in the support of tobacco use prevention and cessation counseling, including integration in undergraduate and graduate dental curricula.
The study was conducted in a dental hospital setting where the tobacco users were identified during the screening procedure and were referred to the tobacco cessation center and thereby the prime motive of every participant constituted the management of dental problems rather than tobacco cessation.
CBT, an effective mode of tobacco cessation, should be applied by any health-care personnel to all tobacco users identified not only in a hospital setting but also should be implemented in all clinical settings, outreach programs, and other community settings.
| Conclusion|| |
Tobacco dependence is an abating and reversing condition and hence tobacco use cessation requires assistance to attain sustained abstinence. The current study assessed the effectiveness of CBT, an added intervention to HE at a dental hospital setting. Dental hospital setting has an advantage of identifying tobacco usage at the earliest during dental screening procedure; imparting knowledge through HE at such a location increases the attempt to quit. However, CBT is more effective increasing the possibility for continuous abstinence and relapse prevention by overcoming the diverse environmental, social, and intrapersonal factors.
We would like to thank Dr. Vidubala, PhD, and Dr. Surender, PhD, Psycho Oncologists, WIA-Cancer Institute, Adyar, Chennai, for training the investigators and the Tobacco Cessation Centre, Tamil Nadu Government Dental College and Hospital, Government of Tamil Nadu, for permitting the conduct of the study at the institute and all the participants of the study for their consent.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
| References|| |
Doll R, Hill AB. Smoking and carcinoma of the lung; preliminary report. Br Med J 1950;2:739-48.
Doll R, Hill AB. The mortality of doctors in relation to their smoking habits: A preliminary report 1954. BMJ 2004;328:1529-33.
World Health Organization. WHO Report on the Global Tobacco Epidemic, 2013: Enforcing Bans on Tobacco Advertising, Promotion and Sponsorship; 2013. p. 8. Available from: http://www.who.int/tobacco/global_report/2013/en/
. [Last cited on 2014 Jul 22].
Global Adult Tobacco Survey India Report 2009-2010. Publication of Ministry of Health and Family Welfare, Government of India in Collaboration with Centre of Disease Control and Prevention, World Health Organisation and International Institute of Population Sciences; 2010. p. 4. Available from: http://www.mohfw.nic.in/WriteReadData/l892s/1455618937GATS%20India.pdf
. [Last cited on 2014 Jul 22].
American Psychiatric Association. Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition (DSM-IV). Washington, DC: American Psychiatric Association; 1994. p. 242-7.
U.S. Department of Health and Human Services. Preventing Tobacco Use among Youth and Young Adults: A Report of the Surgeon General. Atlanta, GA: U.S. Department of Health and Human Services, Centers for Disease Control and Prevention, National Center for Chronic Disease Prevention and Health Promotion, Office on Smoking and Health; 2012.
John J. Tobacco cessation counselling interventions delivered by dental professionals may be effective in helping tobacco users to quit. Are tobacco cessation interventions effective when offered in the dental office or community setting? Evid Based Dent 2006;7:40-1.
Niaura R. Nonpharmacologic therapy for smoking cessation: Characteristics and efficacy of current approaches. Am J Med 2008;121 4 Suppl 1:S11-9.
Fiore MC, Jaen CR, Baker TB, Bailey WC, Benowitz NL, Curry SJ, et al
. Treating Tobacco Use and Dependence: 2008 Update. Clinical Practice Guideline. Rockville, MD: U.S. Department of Health and Human Services, Public Health Service; 2008.
Webb MS, de Ybarra DR, Baker EA, Reis IM, Carey MP. Cognitive-behavioral therapy to promote smoking cessation among African American smokers: A randomized clinical trial. J Consult Clin Psychol 2010;78:24-33.
Kumar N, Shekhar C, Kumar P, Kundu AS. Kuppuswamy's socioeconomic status scale-updating for 2007. Indian J Pediatr 2007;74:1131-2.
Prochaska JO, Wright JA, Velicer WF. Evaluating theories of health behaviour change: A hierarchy of criteria applied to transtheoretical model. Appl Psychol 2008;57:561-88.
Terra MB, Silveria DS, ComposMoreira T, Ferigolo M, Mazoni C, Arena FX, et al
. Convergent validation study of the contemplation ladder for application via telephone in tobacco users. Rev Bras Psiquiatr 2009;58:143-9.
Rollnick S. Readiness, importance, and confidence: Critical conditions of change in treatment. In: Miller WR, Heather N, editors. Treating Addictive Behaviors. 2nd
ed. New York: Plenum Press; 1998.
Heatherton TF, Kozlowski LT, Frecker RC, Fagerström KO. The Fagerström test for nicotine dependence: A revision of the Fagerström Tolerance Questionnaire. Br J Addict 1991;86:1119-27.
Manual for Training in Cancer Control; Manual for Tobacco Cessation, Directorate General of Health Services, Ministry of Health and Family Welfare; Government of India; 2005.
Dingel MJ, Karkazis K, Koenig BA. Framing nicotine addiction as a “Disease of the Brain”: Social and ethical consequences. Soc Sci Q 2012;92:1363-88.
Kmietowicz Z. Doctors told to treat nicotine addiction as a disease. BMJ 2000;320:397.
Leshner AI. Addiction is a brain disease, and it matters. Science 1997;278:45-7.
Bouton ME. Why behavior change is difficult to sustain. Prev Med 2014;68:29-36.
World Health Organization. Health education: Theoretical concepts, effective strategies and core competencies: A foundation document to guide capacity development of health educators. Cairo: World Health Organization, Regional Office for the Eastern Mediterranean; 2012. p. 13.
Janz NK, Becker MH, Kirscht JP, Eraker SA, Billi JE, Woolliscroft JO. Evaluation of a minimal-contact smoking cessation intervention in an outpatient setting. Am J Public Health 1987;77:805-9.
Gordon JS, Andrews JA, Crews KM, Payne TJ, Severson HH, Lichtenstein E. Do faxed quitline referrals add value to dental office-based tobacco-use cessation interventions? J Am Dent Assoc 2010;141:1000-7.
Raja M, Saha S, Mohd S, Narang R, Reddy LV, Kumari M. Cognitive behavioural therapy versus basic health education for tobacco cessation among tobacco users: A randomized clinical trail. J Clin Diagn Res 2014;8:ZC47-9.
Pieterse ME, Seydel ER, DeVries H, Mudde AN, Kok GJ. Effectiveness of a minimal contact smoking cessation program for Dutch general practitioners: A randomized controlled trial. Prev Med 2001;32:182-90.
Carpenter MJ, Hughes JR, Solomon LJ, Callas PW. Both smoking reduction with nicotine replacement therapy and motivational advice increase future cessation among smokers unmotivated to quit. J Consult Clin Psychol 2004;72:371-81.
Nohlert E, Tegelberg A, Tillgren P, Johansson P, Rosenblad A, Helgason AR. Comparison of a high and a low intensity smoking cessation intervention in a dentistry setting in Sweden: A randomized trial. BMC Public Health 2009;9:121.
Lough LE, Ebbert JO, McLeod TG. Evaluation of a student-run smoking cessation clinic for a medically underserved population. BMC Res Notes 2011;4:55.
Stevens VJ, Severson H, Lichtenstein E, Little SJ, Leben J. Making the most of a teachable moment: A smokeless-tobacco cessation intervention in the dental office. Am J Public Health 1995;85:231-5.
Walsh MM, Hilton JF, Masouredis CM, Gee L, Chesney MA, Ernster VL. Smokeless tobacco cessation intervention for college athletes: Results after 1 year. Am J Public Health 1999;89:228-34.
Polanska K, Hanke W, Sobala W, Broszkiewicz M. Smoking cessation intervention during pregnancy in a Polish urban community – What is the target population? Tob Induc Dis 2002;1:121-8.
Molyneux A, Lewis S, Leivers U, Anderton A, Antoniak M, Brackenridge A, et al.
Clinical trial comparing nicotine replacement therapy (NRT) plus brief counselling, brief counselling alone, and minimal intervention on smoking cessation in hospital inpatients. Thorax 2003;58:484-8.
Hanioka T, Ojima M, Tanaka H, Naito M, Hamajima N, Matsuse R. Intensive smoking-cessation intervention in the dental setting. J Dent Res 2010;89:66-70.
Robinson LA, Vander Weg MW, Riedel BW, Klesges RC, McLain-Allen B. “Start to stop”: Results of a randomised controlled trial of a smoking cessation programme for teens. Tob Control 2003;12 Suppl 4:IV26-33.
Raupach T, Shahab L, Neubert K, Felten D, Hasenfuss G, Andreas S. Implementing a hospital-based smoking cessation programme: Evidence for a learning effect. Patient Educ Couns 2008;70:199-204.
Goon S, Bipasha MS. Prevalence and pattern of smoking among bus drivers of Dhaka, Bangladesh. Tob Use Insights 2014;7:21-5.
Nugent KL, Million-Mrkva A, Backman J, Stephens SH, Reed RM, Kochunov P, et al.
Familial aggregation of tobacco use behaviors among Amish men. Nicotine Tob Res 2014;16:923-30.
Ramseier CA, Warnakulasuriya S, Needleman IG, Gallagher JE, Lahtinen A, Ainamo A, et al.
Consensus report: 2nd
European workshop on tobacco use prevention and cessation for oral health professionals. Int Dent J 2010;60:3-6.
[Table 1], [Table 2], [Table 3], [Table 4], [Table 5]