Social-Cognitive and School Factors in Initiation of Smoking among Adolescents: A Prospective Cohort Study Pernille Envold Bidstrup, 1 Kirsten Frederiksen, 2 Volkert Siersma, 3 Erik Lykke Mortensen, 4 Lone Ross, 5 Mathilde Vinther-Larsen, 6 Morten Grønbæk, 6 and Christoffer Johansen 1 Departments of 1 Psychosocial Cancer Research and 2 Statistics and Epidemiology, Institute of Cancer Epidemiology, Danish Cancer Society; 3 Research Unit and Department of General Practice and 4 Department of Health Psychology, Institute of Public Health, University of Copenhagen; 5 Research Unit, Department of Palliative Medicine, Bispebjerg Hospital; 6 Danish National Institute of Public Health, Copenhagen, Denmark Abstract Aims: The aim of the present study was to examine the association between social-cognitive factors, school factors, and smoking initiation among adolescents who had never smoked. Methods: The study was based on longitudinal data on Danish adolescents attending randomly selected public schools. Adolescents enrolled in grade 7 (mean age, 13 years) who had never smoked (n = 912) were fol- lowed up for 6 months after baseline. Those who had still never smoked were followed up again 18 months after baseline, in grade 8 (n = 442). Social-cognitive factors were examined with five measures: self-efficacy, social influence (norms), social influence (behavior), social influence (pressure), and attitude. We used mul- tilevel analyses to estimate the associations between social-cognitive factors at baseline and smoking initi- ation as well as the random effects of school, school class, and gender group in the school class. Results: At the first follow-up, we found significant associations between attitude, father’s smoking, best friend’s smoking, and smoking initiation. At the second follow-up, we found a significant association with pressure to smoke from friends. Of the school factors, gender group in the school class showed an effect at both first and second follow-up. Conclusion: Our results suggest that father’s smoking, best friend’s smoking, attitude, and pressure to smoke from friends affect smoking initiation. The results for school factors suggest an effect of classmates of the same gender, which has not previously been examined longitudinally. (Cancer Epidemiol Biomarkers Prev 2009;18(2):384–92) Introduction To prevent smoking, it is essential to understand why someadolescentsstartexperimentingwithcigarettesand some do not. Several social and psychological factors have been suggested to affect smoking initiation, and severaltheorieshavebeenproposedtodescribehowand why these factors are related to smoking initiation. Ideally, these theories would allow precise prediction of smoking initiation and thus form a basis for prevention. One proposed theory is the ASE model, which suggests that attitude, social influence (smoking, norms, and pressure from parents and friends), and self- efficacy(believingthatonewillbeabletorefusecigarette offers) influence the decision to experiment with ciga- rettes (1, 2). The ASE model was developed by de Vries and colleagues (1). It is an integrative model, combining theoretical constructs from cognitive affective theory, specifically the ‘‘theory of reasoned action’’ of Fishbein and Ajzen (attitude, social norms, self-efficacy, and pressure), and the ‘‘social cognitive learning theory’’ of Bandura (behavior of others and self-efficacy; ref. 3). The theory of reasoned action states that the intention todocertainbehavioristhemostimportantdeterminant of later behavior (4). Beliefs about the personal con- sequences of behavior (attitude) are seen as the most importantpredictorofintentionandactualbehavior.The social-cognitive learning theory of Bandura also focuses on intention and attitude but also emphasizes behavior- specific modeling or imitation in the acquisition of social behavior (5). The self-efficacy construct was introduced by Bandura in his social cognitive learning theory, and a similarbutbroaderconstructwaslateradoptedbyAjzen in his theory of planned behavior, where it was called ‘‘perceived behavioral control.’’ In a previous article (6), we extended the ASE model by adding three school factors and thus taking into account the fact that ado- lescentsareaffectedbypeopleintheirproximity(Fig.1). Previous studies, including two reviews, have shown that the school (7–10), the school class, and the gender groupintheschoolclass(11)mayplayimportantrolesin smoking status. The school environment can be impor- tant because adolescents at the same school share attributes, such as their physical environment and neighborhood. Adolescents in the same school class furthermore have the same teachers and spend up to 9 years together on school days. Adolescents in the same gender group (boys versus girls) in a school class also often share friends (12). These school factors have been found to be of particular importance in studies in which Cancer Epidemiol Biomarkers Prev 2009;18(2). February 2009 Received9/9/08;revised10/21/08;accepted10/29/08;publishedOnlineFirst02/03/2009. Grant support: Pharmaceutical Foundation of 1991 (Apoterkerfonden af 1991), Danish Lung Association’s Research Foundation (Danmarks Lungeforenings Forskningsfond), and Foundation of 17.12.1981 (Fonden af 17.12.1981). Requests for reprints: Pernille Envold Bidstrup, Department of Psychosocial Cancer Research, Institute of Cancer Epidemiology, Danish Cancer Society, Strandboulevarden 49, DK-2100 Copenhagen, Denmark. Phone: 45-3525-7600; Fax: 45-3525-7721. E-mail: pernille@cancer.dk Copyright D 2009 American Association for Cancer Research. doi:10.1158/1055-9965.EPI-08-0584 384 on May 17, 2017. © 2009 American Association for Cancer Research. cebp.aacrjournals.org Downloaded from