Tobacco use and smoking cessation among third-year dental students in southern Brazil

Abstract

The aim of the present cross-sectional study was to assess tobacco use and smoking cessation among third-year dental students in southern Brazil. The Global Health Professions Student Survey questionnaire was used in eight dental schools in Rio Grande do Sul state, Brazil. Of the 663 eligible students, 576 (87%) participated. The prevalence of current smoking was 19.1% [95% confidence interval (CI): 12.9–25.3%], and 61.6% (95% CI: 54.9–68.3%) of students reported having smoked at least once in their lifetime. The prevalence of dental students who had smoked ≥100 cigarettes in their lifetime was 17.1% (95% CI: 12.5–21.7%). Being frequently exposed to other smokers at home or in other places (second-hand smoke) increased the likelihood of current smoking by two- to threefold. Approximately 6.1% (95% CI: 3.5–8.7%) of the students reported that they currently wanted to stop smoking and 7.5% (95% CI: 5.3–9.6%) had tried to stop smoking in the last year. Friends and family were the most frequent sources of help or counselling, and only a limited proportion of students received help from health professionals. Tobacco use and exposure to second-hand smoking is widespread among dental students in southern Brazil. Smoking-cessation initiatives targeting health care students are urgently needed.

INTRODUCTION

Smoking is recognised as a major risk factor for several diseases and conditions, and it has been associated with a substantial proportion of the global burden of these diseases¹. Smoking is still a widespread habit, with more than 1.3 billion smokers worldwide; of these, approximately 1 billion live in developing countries². A recent literature review revealed that the prevalence of smoking among health professionals is generally lower than in the general population and it has declined in the last 30 years³. Overall, the prevalence of tobacco use among health professionals has been reported to be <10% in developed countries, whereas a higher occurrence has been reported in developing countries⁴. Smoking among dentists has not received particular attention in the literature, with few studies reporting tobacco use and smoking cessation. A review addressing this issue⁵ showed that the prevalence of smoking among dentists is low in the USA, Finland, Australia and Canada. Nevertheless, two studies6., 7. showed a higher prevalence of smokers among dentists than among physicians.

Few studies have investigated the prevalence of smoking among health-profession students, and this is especially true for dentistry⁸. The World Health Organisation, the US Center for Disease Control and Prevention and the Canadian Public Health Association have introduced an initiative called the Global Tobacco Surveillance System (GTSS)⁹. The GTSS has several components, one of which is the Global Health Professions Student Survey (GHPSS), a school-based survey of third-year students in medicine, dentistry, nursing and pharmacy. The GHPSS uses a validated questionnaire that collects data on demographics, tobacco use, knowledge and attitudes about tobacco use and training received regarding patient counselling on smoking-cessation techniques. A recent publication compiling data collected globally between 2005 and 2009 demonstrated a wide range of smoking habits among medical¹⁰, nursing¹¹ and dental¹². The prevalence of current cigarette smokers among dental students ranged from 2.1% in Cambodia to 65% in Moldova.

Health professionals are clearly not immune to the deleterious effects of smoking. As shown by large longitudinal studies of health professionals13., 14., smoking greatly increases morbidity and mortality from cardiovascular disease, respiratory problems and cancer, with obvious personal, population and economic repercussions. It has also been shown that health professionals who smoke are less likely to engage in smoking-prevention and smoking-cessation efforts15., 16., underscoring the importance of smoking-prevention and smoking-cessation initiatives for these professionals8., 17.. Therefore, tobacco use among future health professionals is likely to have major public health and economic impacts. The aim of the present study was to assess tobacco use and smoking cessation among third-year dental students in southern Brazil.

MATERIALS AND METHODS

Study design and target population

The present investigation was a cross-sectional study and included all dental schools in Rio Grande do Sul state, Brazil. Rio Grande do Sul is located in the southernmost part of Brazil, bordering Argentina and Uruguay, and has a total population of approximately 10 million inhabitants¹⁸. The state has eight dental schools located in 10 different campuses comprising five private and three public institutions. The target population of this study was 663 third-year dental students enrolled between 2006 and 2008.

Sample size and study sample

A worst-case scenario approach, based on a prevalence of 50% for the sample size calculation, was used because no data regarding smoking habits among dental students in this area were available. It was estimated that 589 students would yield a precision of 4% for the 95% confidence interval (95% CI) for a prevalence of 50%. As the required sample size was very similar to the sample size of the target population we decided to include all third-year students in the survey to account for non-response. Eligibility to participate in the study was determined by the student listing provided by all dental schools. Of the 663 eligible third-year students, 84 declined to participate, yielding a response rate of 87%. Overall, 579 students responded to all questions and three questionnaires were incomplete (Table 1).

Table 1.

Sample characteristics

Variable	n	%
Age (years)
≤20 years	179	31.1
>20 but <23 years	217	37.7
≥23 years	180	31.3
Gender*
Male	188	32.6
Female	386	67.3
Race
White	542	94.1
Other	34	5.9
Socio-economic status
High	218	37.9
Middle	210	36.5
Low	119	20.7
Unknown	29	5.0
School
Public	189	32.8
Private	387	67.2
Total	576	100.0

^*Missing gender data for 2 participants.

Questionnaire

The GHPSS questionnaire was used to gather sociodemographic data, behaviour, knowledge and attitudes regarding tobacco use, smoking prevention and smoking cessation. The questionnaire comprised 66 multiple-choice questions. The version used in the present study was validated by the Brazilian National Institute of Cancer¹⁹. Family socio-economic status was assessed using a standard Brazilian economic classification²⁰. Data were collected between November 2006 and August 2008. Eligible, consenting participants were interviewed in the classroom before or after lectures and activities. Trained assistants administered the self-reported questionnaire and were available to assist if help was requested.

Quality control

Participation was encouraged by explaining the background and aims of the study. The response rate was improved by scheduling the data collection for periods of the semester and times of the day that had minimal impact on the daily activities of the students. Alternative schedules were offered to students who could not participate during regular hours.

Questionnaires were reviewed for completeness to minimise missing data. Reproducibility of the questionnaire was evaluated by test–retest and 15 students were re-interviewed within 30 days of the first questionnaire. Ten core questions comprising demographics, smoking habits and attitudes were used. Overall, the unweighted kappa was 0.77, indicating good reproducibility.

Ethical considerations

The study protocol was reviewed and approved by the Ethical Committee on Research of the School of Dentistry, Federal University of Rio Grande do Sul. Approval for conducting the study was sought separately in each dental school through the administration and local Institutional Review Boards. Permission to conduct the study was granted for all dental schools. Students who agreed to participate signed an informed consent form. This research was conducted in full accordance with the World Medical Association Declaration of Helsinki.

Data analysis

Data analysis was performed using STATA software (Stata 11.1 for Mac; Stata Corporation, College Station, TX, USA) and using survey commands that take into account the clustering of observations within the dental schools. Pairwise comparisons of crude estimates were carried out using the Wald test. The chosen level of statistical significance was P < 0.05. A multiple logistic regression was used to model the relationship between self-reported current smoking and various explanatory variables. Prevalence, odds ratios (ORs) and 95% CI were calculated and reported. Dental students were classified as current smokers if they had smoked cigarettes at least once in the last month.

RESULTS

Tobacco use

The prevalence of current smoking among third-year dental students was 19.1% (Table 2), with no significant differences between genders (P = 0.80). Most students smoked 5 days or fewer in the last 30 days and approximately one-quarter reported smoking daily or almost every day. The majority of current smokers consumed <1 cigarette/day, 28.5% smoked 1–10 cigarettes/day and approximately 15% smoked more than 10 cigarettes/day. Male students were twice as likely to smoke 11 cigarettes/day or more compared with female students (56.25% vs. 23.53%, respectively; P = 0.03).

Table 2.

Prevalence of current cigarette smoking according to tobacco use (n = 576)

Variable	All students		Only smokers
	%	95% CI	%	95% CI
Number of days dental students reported smoking in the last month
1–5 days	10.4	6.8–14.1	55.1	42.6–67.5
6–19 days	3.3	1.6–5.1	17.4	11.4–23.5
20–29 days	2.3	1.2–3.3	11.9	6.6–17.2
Every day	3.0	1.1–4.8	15.6	8.8–22.4
Average number of cigarettes smoked per day
<1 cigarette/day	11.5	7.7–86.1	56.9	45.1–68.7
1–10 cigarettes/day	5.7	2.8–8.7	28.5	19.0–37.9
11 or more cigarettes/day	3.0	1.1–4.8	14.7	6.6–22.7
Total	19.1	12.9–25.3	100	–

Overall, 61.6% of students reported having smoked one cigarette or more in their lifetime (Table 3). This occurrence was significantly higher among male students than among female students (69.7% vs. 57.5%, respectively; P = 0.005). Most female students smoked for the first time at early age, whereas most male students smoked for the first time later in life. Most students smoked light cigarettes. Overall, 23.61% of the students reported having used other tobacco products (cigars, pipe, chewing tobacco, other) at least once in their lifetime, and 6.1% reported current use (at least once in the last 30 days) of other tobacco products. Male students were more likely to report using other tobacco products compared with female students (30.85% vs. 19.95%, respectively; P < 0.001). The prevalence of dental students who had smoked 100 cigarettes or more in their lifetime was 17.1% (95% CI: 12.5–21.7%), and no significant differences were observed between genders (P = 0.54). Smoking at the University campus within the last year was reported by 8.2% (95% CI: 3.1–13.2%) of the students. Only 43.6% (95% CI: 31.6–55.5%) of the students knew about the University policies on smoking, and smoking-free environment policies did not influence their behaviour regarding smoking at the University campus (P = 0.25).

Table 3.

Prevalence of dental students who have smoked at least once in their lifetime according to gender and age when first cigarette was smoked (n = 574)

Age when first cigarette was smoked	Male students	95% CI	Female students	95% CI	Total	95% CI
15 years or younger	25.8	17.8–33.8	27.2	20.8–33.6	27.0	23.4–30.6
16–17 years	27.4	18.8–36.1	14.8	11.5–18.0	18.8	14.9–22.7
18–19 years	11.3	5.2–17.4	11.1	7.5–14.8	11.1	7.36–14.9
20 years or older	4.8	0.5–9.2	4.2	2.0–6.3	4.4	2.3–6.4
Total	69.7	62.3–77.1	57.5	49.8–65.2	61.6	54.9–68.3

Pearson chi-square design-based P-value: 0.04.

Willingness to stop smoking

Approximately 6.1% (95% CI: 3.5–8.7%) of the students reported that they currently wanted to stop smoking and 7.5% (95% CI: 5.3–9.6%) had tried to stop smoking in the last year. Female students tried significantly more often to stop smoking than did male students (8.6% vs. 5.3%, respectively; P = 0.03). Overall, 11.5% of the students received help or counselling for smoking cessation (Table 4). Friends or family were the most frequent source of help or counselling, and only a small proportion of students received help from health professionals. Smoking cessation for 1 year or more was reported by 13.9% (95% CI: 9.6–18.1%) of students and 5.7% (95% CI: 2.3–9.1%) reported that they had stopped smoking for <1 year.

Table 4.

Smoking cessation among dental students who want to stop smoking

Source of help or counselling to try to stop smoking	%	95% CI
Health professional	0.9	0.0–1.9
Friend	3.5	1.4–5.5
Family	3.5	1.2–5.7
Other	3.7	1.6–5.7
Total	11.5	7.8–15.1

Exposure to second-hand smoke

Recent exposure to second-hand smoking at home was reported by 31.6% (95% CI: 23.7–39.6%) of students. Approximately half of these students reported that they were exposed to second-hand smoke on a daily or almost daily basis (15.5%; 95% CI: 9.8–21.1%). Exposure to second-hand smoke in other environments was very prevalent, affecting 73.6% (95% CI: 67.7–79.6%) of students. Daily exposure, or exposure almost every day, to second-hand smoke was reported by 22.9% (95% CI: 14.9–30.9%) of students.

Predictors of current smoking

Table 5 presents the univariable and multivariable analysis of predictors for current smoking among dental students. Being frequently exposed to other smokers at home or in other places were the only factors significantly associated with smoking at least once in the last month. Dental students frequently exposed to smoking in their households or other places were, respectively, two and three times more likely to have smoked in the last 30 days than were students not exposed to smoking. No significant associations were observed between current self-reported smoking and age, gender, socio-economic status, school type and tobacco-free environment at the University.

Table 5.

Univariable and multivariable association between current smoking (smoking at least once in the last month) and demographics, socio-economic status, exposure to smoking, school type and tobacco-free environment policies

Characteristic	Univariable OR (95% CI)	Multivariable OR (95% CI) (n = 576)
Gender
Male	1.0
Female	0.9 (0.5–1.7)
Age (years)
≤20 years	1.0
>20 but <23 years	1.1 (0.6–2.0)
≥23	1.2 (0.7–2.1)
Socio-economic status
High	1.0
Middle	0.8 (0.6–1.0)
Low	0.7 (0.4–1.3)
Exposure to smoking at home in the last 7 days
No	1.0	1.0
1–4 days	2.0 (1.3–3.1)**	1.6 (0.9–2.8)
5–7 days	3.2 (2.0–5.2)**	2.0 (1.1–3.4)*
Exposure to smoking at other places in the last 7 days
No	1.0	1.0
1–4 days	1.3 (0.7–2.7)	1.2 (0.6–2.5)
5–7 days	4.3 (2.3–7.8)**	3.1 (1.6–5.8)**
Tobacco-free environment is enforced at the University
Enforced	1.0
Not enforced	1.5 (0.8–2.7)

^*P < 0.05; **P < 0.01.

DISCUSSION

This cross-sectional study was conducted to assess tobacco use and smoking cessation among third-year dental students in southern Brazil. Approximately two-thirds of dental students reported having smoked at least once, and 17% had smoked 100 cigarettes or more in their lifetime. Most students could be classified as light smokers (1–10 cigarettes/day). Male students were more likely to smoke and to be heavy smokers than were female students. Dental students frequently exposed to other smokers at home or other places were more likely to be current smokers. Approximately 6% of the students reported that they currently wanted to stop smoking, 7.5% had tried to stop smoking in the last year and 14% had stopped smoking for 1 year or more. Friends or family were the most frequent source of help or counselling, and only a small proportion of students received help from health professionals.

The prevalence of smoking among health profession students has only recently received the necessary attention in the literature3., 11., 12., 21.. Between 2005 and 2009, the Dental component of the GHPSS collected data from over 12,000 third-year dental students from 44 countries and four cities/sites¹². Smoking estimates ranged widely, with the majority of the sites reporting a prevalence of current smokers of between 10% and 30%, with male students being more likely than female students to smoke in most of the sites. Rio de Janeiro was the only city surveyed in Brazil, and 304 dental students participated. The prevalence of current cigarette smokers was 20% and was significantly higher among male students than among female students. Similar results were observed in our study, with 19.1% of students reporting having smoked in the last 30 days. The small difference in prevalence of current smoking among dental students is somewhat surprising because the state has the highest prevalence of smoking among adults in Brazil²². Our finding, that the prevalence of current smoking was not significantly different between genders, is in contrast to national estimates which have shown a higher prevalence of smoking in male subjects than in female subjects²². To the best of our knowledge, no other studies have assessed tobacco use more broadly among dental students in Brazil.

In this study, 6.1% of the students reported that they currently wanted to stop smoking and 7.5% had tried to stop smoking in the last year. Among them, only a small proportion sought or received help from health care professionals. These findings highlight the need for smoking-cessation initiatives personalised to these students. A recent review summarised the potential of several smoking-cessation programmes delivered to college students, including, but not restricted to, telephone-based counselling, text messages and Internet-based programmes with content tailored for college students²³. Although many interventions have demonstrated effectiveness in a short-term follow-up, few have proven long-term results and relapses frequently occurred in social situations.

The prevalence of second-hand smoking at home or in other places was high among dental students from southern Brazil, and similar estimates were observed in the Rio de Janeiro sample of the GHPSS¹². Studies have shown that college students are especially vulnerable to developing nicotine dependence and are strongly targeted by advertisements of the tobacco industry²⁴. In this context, the finding that only variables related to exposure to second-hand smoking were able to predict current smoking underscores the need for environmental strategies, including prohibition of tobacco use and banning advertisements on campus to prevent smoking among dental students. It is also evident that university policies on smoking/smoke-free campus are not being effectively communicated and/or enforced. Less than 50% of students were aware of their university’s policies on this matter and approximately 10% had recently smoked at the university campus.

The validity of the estimates of any study dealing with health behaviour among health professionals is always a concern. Their commitment to health constitutes an obvious conflict with smoking, and because health care professionals are widely viewed as role models, their response to smoking-related questionnaires may be biased. Additionally, the possibility of desirability bias may not be excluded. To minimise these potential problems the GHPSS questionnaire was anonymous and self-administered. Moreover, the test–retest approach used to evaluate the reproducibility questionnaire showed high consistency of the data. Among the strengths of the present study are high response rate, moderate sample size and the use of an internationally validated questionnaire.

Smoking among health professionals has several consequences for society. First, smoking increases morbidity and mortality of health professionals and this has an obvious health economic impact by decreasing the number of productive years of these highly educated and skilled professionals. Second, health professionals who smoke are less likely to engage in smoking-prevention and smoking-cessation efforts, precluding prevention of several smoking-related diseases⁴. Finally, smoking may pose an obstacle to progression of their careers because restrictions on smoking are becoming increasingly common and several health care organisations have adopted a ‘non-smoker-only’ hiring policy, despite ethical concerns about this directive²⁵.

CONCLUSION

In conclusion, tobacco use and exposure to second-hand smoking appears widespread among dental students in southern Brazil. Smoking-cessation initiatives targeting health care students are urgently needed. Universities have to communicate and enforce their smoke-free policies more effectively.

Acknowledgement

The authors would like to thank all dental students who participated in this study.

Conflict of Interest

The authors declare no conflict of interest.