Preventive Medicine 70 (2015) 26–32

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Evaluation of a brief counseling for tobacco cessation in dental clinics among Swedish smokers and snus users. A cluster randomized controlled trial (the FRITT study) Suvi E. Virtanen a,1, Zangin Zeebari a,b,1,2, Izla Rohyo c,3, Maria R. Galanti a,b,1,2,⁎ a b c

Department of Public Health Sciences, Karolinska Institutet, Stockholm, Sweden Centre for Epidemiology and Community Medicine, Stockholm Health Care District, Sweden Dentistry Clinic Solvändan, Sörmland Health Care Region, Mariefred, Sweden

a r t i c l e

i n f o

Available online 18 November 2014 Keywords: Tobacco use cessation Counseling Dental care Randomized controlled trial

a b s t r a c t Objective. The aim of this study is to assess the effectiveness of a very brief structured counseling for tobacco cessation in dentistry clinics. Method. A cluster randomized trial was conducted in Sweden in 2012–2013. Twenty-seven dentistry clinics in two Swedish counties were randomized to provide either a structured brief advice based on the 5 A's model or usual care. Participants were 467 patients currently using tobacco daily (225 in the intervention group and 242 in usual care), of which 97% were retained at follow-up, six months after enrolment. Study outcomes were: 7-day abstinence (primary outcome); 3-month sustained abstinence; 50% reduction of the amount tobacco used; quit attempts lasting at least 24 h. Results. Compared to usual care, brief counseling was not associated to statistically significant increase in the proportion abstinent from tobacco use after 6 months. However, there was a statistically significant association with reduction of tobacco consumption (OR = 2.07 95% CI 1.28–3.35). Changes in the expected direction for all outcomes were more frequent in the intervention than in the usual care group, and larger among exclusive snus users than among smokers. Conclusions. Very brief and structured counseling in dentistry may achieve positive behavioral modifications among tobacco users, with significant reduction of tobacco consumption, particularly among smokeless tobacco users. © 2014 Elsevier Inc. All rights reserved.

Introduction Helping cigarette smokers to quit is one of the most cost-effective and egalitarian investments a health-care system can set on its agenda (Gollust et al., 2008). Most tobacco users are motivated to quit. For instance, in Sweden about 8 out of 10 of current cigarette smokers have made a serious attempt in this direction (Fagerstrom et al., 2001). Not much is known on trajectories of behavioral

⁎ Corresponding author at: Department of Public Health Sciences, Karolinska Institutet, Tomtebodavägen 18a, 17177 Stockholm, Sweden. E-mail addresses: [email protected] (S.E. Virtanen), [email protected] (Z. Zeebari), [email protected] (I. Rohyo), [email protected] (M.R. Galanti). 1 Postal address: Department of Public Health Sciences, Karolinska Institutet, Tomtebodavägen 18a, 17177 Stockholm, Sweden. 2 Postal address: Centre for Epidemiology and Community Medicine, Box 1497, 171 29 Solna, Sweden. 3 Postal address: Folktandvården Sörmland AB Folktandvården Marie Box 134 647 23 Mariefred, Sweden.

http://dx.doi.org/10.1016/j.ypmed.2014.11.005 0091-7435/© 2014 Elsevier Inc. All rights reserved.

changes among smokeless tobacco users, but studies indicate that the proportion attempting to quit may be lower (Agaku et al., 2013; Panda et al., 2014). In a Swedish national survey in 2013 about 42% of the users of the smokeless tobacco snus reported willing to quit, in contrast to 73% of the cigarette smokers (Public Health Agency of Sweden, 2014). Irrespective of motivation and intentions, the proportion achieving a sustained abstinence among tobacco users trying to quit on their own is low. In observational studies, it has been estimated that the likelihood of protracted abstinence from smoking following an unassisted quit attempt is about 12% (Zhou et al., 2009). A number of treatments—both pharmacologic and based on behavioral modification have proven to be highly effective in increasing smoking cessation rates by a factor of two, representing some of the most cost-effective clinical interventions available today (Stead and Lancaster, 2012). Non-pharmacologic interventions typically include support to behavioral modification resting on different theoretical assumptions, methods and intensities (Fiore et al., 2008; The Swedish National Institute of Public Health, 2009). Higher treatment intensity, longer

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counseling time or higher numbers of contacts are likely to increase abstinence rates in a dose-response fashion (Fiore et al., 2008). In the newly released guidelines to lifestyle modification in health care services the Swedish National Board of Health and Welfare (2011a) establishes a gradient of increasing effectiveness from the simple medical advice to quit to high-intensity counseling, including proactive telephone counseling. Similar guidelines have been issued for dental health care (The National Board of Health and Welfare, 2011b). These recommendations are similar to the guidelines by the U.S. Department of Health and Human services that advocate the combined use of counseling and medications, as well as the use of telephone quit-lines (Fiore et al, 2008). However, a Cochrane review indicates that even a one-time individual counseling of at least 10 min may be sufficient to increase the proportion abstinent compared to minimal intervention, i.e. counseling or advice of shorter duration (Lancaster and Stead, 2005). Earlier studies showed favorable effects of counseling of even shorter duration (Slama et al., 1995). Questions of effectiveness linked to the intensity of tobacco cessation counseling have a direct bearing on what represents an optimal provision of this type of treatment in health care systems. High accession facilities certainly represent an optimal setting for tobacco cessation interventions, because of their large population reach. In Sweden this is the case for dental care. Due to the extensive state-wide subsidies and the emphasis on oral health promotion 84–90% of the adult population visits dentistry clinics during two years (Clevenpalm and Karlsson, 2009; Hjern et al., 2001; The National Board of Health Welfare, 2010). Also, the negative consequences of tobacco use for oral health, such as oral cancer and poor periodontal health in smokers and local lesions in snus users, give high legitimacy to dental professionals to provide tobacco cessation support to their patients (Cnattingius et al., 2005; Scientific Committee on Emerging and Newly Identified Health Risks, 2008; Swedish Council on Health Technology Assessment, 2002; U.S. Department of Health and Human Services, 2004). In fact, both a recent Cochrane review and a report by Swedish Council on Health Technology Assessment concluded that tobacco cessation interventions in dental care clinics are effective in increasing the abstinence rates among tobacco users (Carr and Ebbert, 2012; Swedish Council on Health Technology Assessment, 2002). Despite this encouraging evidence tobacco cessation activities are not widely implemented in dental care (Amemori et al., 2013; Axelsson et al., 2006; Halling et al., 1995; Prakash et al., 2013). Lacks of time, of financial resources, and of professional skills were reported by dental care professionals as major obstacles to provide tobacco cessation support (Helgason et al., 2003; Nasser, 2011; Prakash et al., 2013; Preber and Åkerberg, 2000). Therefore, effective low-intensity interventions in this setting would be very valuable. To our knowledge there are no Swedish studies evaluating the effectiveness of very brief tobacco cessation counseling in dental care. In fact, the only Swedish trial conducted in dentistry clinics compared an intensive counseling including eight 40-minute sessions with a shorter version of the same intervention (Nohlert et al., 2009). To fill this gap, a cluster randomized trial (The FRITT study—Swedish acronym for “Free from Tobacco in Dentistry”) was designed to evaluate the effectiveness of a very brief and structured tobacco cessation counseling conducted in dental clinics compared to usual care. The study was promoted by the National Board of Health and Welfare on behalf of the Swedish government. Methods The study was approved by the Ethical Review Board of Stockholm Region, March 15, 2012 (nr. 2012/237-31/5). The trial was registered in the ISRCTN Register of controlled trials with identification number ISRCTN50627997.

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Evaluation design A cluster randomized design was chosen to evaluate the effectiveness of the intervention with dental clinics allocated to either of the trial conditions. Cluster randomization was employed, despite the intervention was delivered at individual level, in order to avoid contamination of the trial conditions and because of feasibility reasons. Intervention The intervention was developed by two chartered psychologists employed by the Swedish National Institute of Public Health, to be delivered individually to patients visiting dental clinics by a dentist or by a dental hygienist. It consisted of a structured very brief advice (planned duration of maximum 5 min) based on the 5 A's. This latter is a 5-step model developed to promote behavioral changes in brief interventions, here described with reference to tobacco use: 1) Asking about tobacco use, 2) Advising to quit, 3) Assessing willingness to quit, 4) Assisting the tobacco user in quitting, for instance by providing information on available counseling and medications and 5) Arranging follow-up contacts (Fiore et al., 2008). The use of the 5 A's approach is advocated for routine tobacco cessation in dental care settings as well as in other health care settings (Fiore et al., 2008; Ramseier and Fundak, 2009). In the proposed intervention: 1. asking about tobacco use followed a structured path, especially inquiring on recent and habitual amount. 2. in advising to quit, the dental health care professionals were instructed to specifically refer to patients' oral health. 3. motivation to quit was assessed with questions prompting the patient's thoughts and possible interest to proceed to a quit attempt 4. standardized information was provided on pharmacotherapy and other available support to quit, e.g. more intensive counseling available at primary care clinics and via the Swedish national telephone quit-line (Sluta röka-linjen). The availability of this external counseling was not manipulated in the study. A leaflet about the quitting process was also offered. 5. lastly, the advisor informed the patient that a follow-up visit was planned after six months. Dentistry staff was trained to deliver the intervention during a one-day workshop conducted by the two developers. Information was provided about tobacco harms, dependence and cessation. The counseling technique was demonstrated with the use of interactive teaching techniques such as role playing, films, simulations and group discussions. Study protocol and data collection procedures were illustrated at this stage. Control condition Patients in the control condition received assistance to tobacco cessation according to the usual praxis established at the clinic (if any). No attempts were made to standardize this condition, but a record was kept of the type and duration of advice provided to each patient. These records indicated that no advice was given to about 28% of the participants in the control condition. When given, it mainly consisted of information about consequence of tobacco use for oral health. The staff at control clinics participated in a half-day workshop on the study protocol and data collection procedures, similar to staff in the intervention condition (see above). Outcome definition The primary outcome was defined as total abstinence from tobacco (both cigarettes and snus) during the seven days preceding the follow-up survey. Secondary outcomes were: a. sustained abstinence from all tobacco during the three months preceding the survey; b. reduction by half of the number of cigarettes smoked or snus portions used daily compared to baseline and c. quit attempts lasting at least 24 h in the course of follow-up. All outcomes were based on patients' self-reports. Sample size The desired sample size was calculated with reference to the primary outcome, assuming a proportion of patients abstinent at follow-up of 10% in the control group, an attrition of 13% and 80% power to detect as statistically significant a relative risk (RR) of abstinence of 2.0 in the intervention vs. control group at 6-month follow-up, with alpha error of 5% (double tailed). In order to accommodate for the cluster design, the estimated sample size was augmented by an inflation factor calculated according to: 1 + (m − 1) ρ, where m represents the mean number of patients in each cluster (estimated

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equal to 18) and ρ represents the intra-class correlation coefficient (ICC), estimated to be 0.01 according to the median ICC estimated by Adams et al. (2004). Study protocol Timeline Dental clinics were approached between May and August 2012. Patients were recruited between October 2012 and January 2013 and the follow-up was completed in November 2013. Recruitment of the clinics and of dental care personnel The dental clinics contacted for this study were located in two Swedish counties, Södermanland and Gävleborg. Eligible were both private and public dental care clinics if they provided general dental care, while clinics exclusively delivering specialized care were not eligible. In Södermanland all eligible clinics were invited to participate in the study, and the decision on participation was taken by the head of each clinic. Due to time constraints, in Gävleborg only public dental clinics were approached, and the decision was taken by health care district managers. At each clinic two treatment staff (i.e. dentists or dental hygienists) and one administrative staff were involved in the study.

Descriptive analyses were performed using SAS, version 9.3, (SAS Institute, Cary, North Carolina). The association between intervention condition and outcomes was analyzed in multi-level regression models with random intercept, in order to take the hierarchical structure of the data into account, because individual patients were nested in higher order aggregates, i.e. clinics. Since all outcomes were treated as dichotomous, we used logistic regression, with adjustment for age where appropriate. Results are given as Odds Ratios (OR) and corresponding 95% Confidence Intervals (CI). All analyses were performed according to intention to treat (Altman, 1991). A conservative approach of treating participant lost at follow-up as not having changed their tobacco use was employed for sensitivity analyses. To test for the significance of the difference in treatment effect between smokers and snus users an interaction term was included in the regression models. The multilevel analyses were performed using MLwiN version 2.28 (Centre for Multilevel Modelling, University of Bristol), while SPSS version 22 (IBM Corp., Armonk, NY) was used to estimate the interaction effects for the sub-group analysis.

Results Randomization Clinics were randomized to either the intervention or the usual care (control) condition with 1:1 ratio, using a computer-generated random sequence. The random allocation was performed after all clinics consented to enrolment; therefore it could not be foreseen at the time of acceptance. Recruitment of patients Participants were recruited among patients seeking care at the clinics during the study period, who were eligible if between 18 and 75 years of age, had used tobacco daily since at least one year, and were still current users. Patients should also have a sufficient understanding of the Swedish language. Patients were excluded if presenting with acute dental illness; having severe psychiatric disease, alcohol problems or use of illicit drugs; and being currently involved in other cessation programs. Consecutive patients booked for a visit at the participating clinics during the study period were briefly informed on the study and asked to fill in a screening form, which was used to assess the eligibility for the study. Five clinics deviated from this step of the protocol and either did not keep records of the screened patients or only enrolled consecutive patients who were known to be tobacco users. Eligible patients received complete information on the study and were asked to provide written consent to be included. Information and data collection Patients. Consenting patients completed a paper-and-pencil baseline questionnaire on the spot. The instrument included questions on tobacco use, previous attempts to quit, intention to quit, use of medications as aid to tobacco cessation, a tobacco dependence index (Heaviness of Smoking Index, HSI) (Borland et al., 2010), general health and socio-demographics. Follow-up information was collected approximately six months after the first visit, again with a selfadministered questionnaire including questions on tobacco use in the past 7 days, quit attempts during the follow-up period, duration of current and past abstinence periods, use of other professional support and/or of pharmacologic treatment for tobacco cessation. Patients could opt for answering the followup survey during a scheduled visit at the clinic, at home as mailed questionnaire, or during a telephone interview in occasion of reminders. About one third of the patients chose one of the two latter alternatives. Monitoring of the intervention. The treatment personnel at both intervention and control sites documented on a structured form all tobacco cessation related activities during the visits with the patients included in the study, above all duration and content of tobacco cessation counseling, such as type of advice provided, topics discussed, any arrangement for continued cessation support. Statistical methods Descriptive statistics on the study population are presented as proportions for categorical variables and as mean values with corresponding standard deviation (SD) for continuous variables. When comparing trial groups, differences between proportions were assessed by chi-square test and differences between means with t-test. The conventional significance level of 0.05 was used in all analyses in order to reject the null hypothesis of no difference between groups.

In Gävleborg County 17 public dental clinics were invited to participate, of which 16 agreed. In Södermanland County 65 private and public dental clinics were contacted, of which 2 private and 9 public dental clinics agreed. Of 623 eligible patients 467 (75%) agreed to participate (Fig. 1). The participation rate was slightly higher among patients attending the control clinics (79%) than among those attending the intervention clinics (71%). Among the participants 452 provided follow-up information (97% retention, with no difference between intervention and control group). Patients lost to follow-up belonged to the youngest age group to a higher extent than those retained at follow-up, but there were no other significant differences between these two groups. Tables 1 and 2 show demographic and tobacco use characteristics of the participants at baseline. There were no significant differences in demographic and tobacco history characteristics between patients in the two experimental conditions with the exception of age, participants in the control group being in average 3 years older than those in the intervention group (Table 1). Overall, 43.6% of the participants reported only using snus, 47.5% being exclusive cigarette smokers while 8.9% were dual users (both smoked and used snus daily). Previous quit attempts were reported by 86.7%, and this proportion was higher among smokers than snus users. However, 62.4% reported no definite intention to quit (Table 2). At follow-up, 18 participants in the intervention and 14 in the control condition reported having been abstinent from tobacco in the 7 days preceding the survey. In unadjusted analyses, the odds of 7-day abstinence were 40% higher in the intervention compared with the control condition, but the estimates were rather imprecise and not statistically significant, as seen in Table 3. The same pattern was seen for two of the secondary outcomes with higher, but not statistically significant proportions of sustained abstinence and of attempts to quit in the intervention group compared to control. However, the intervention was associated with a significant two-fold increase in the odds of having reduced tobacco consumption by half at follow-up compared to baseline (OR = 2.07 CI = 1.28–3.35). The adjustment for age did not materially affect the results. To investigate whether the effects of the program differed according to the tobacco product habitually consumed we conducted a separate analysis of cigarette smokers and snus users, shown in Table 4. Beneficial changes in tobacco use associated with the experimental counseling were larger among snus users than among cigarette smokers. However, a formal test for interaction between experimental condition and type of tobacco used did not attain statistical significance at the 0.05 level. A sensitivity analysis treating participant with missing values as not having modified their tobacco use yielded practically no change in any of the estimates.

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Fig. 1. Flow chart of enrolment of clinics and patients in the study.

Discussion The FRITT randomized controlled trial represents the first experimental study in Sweden aiming at outcome evaluation of a brief structured counseling for tobacco cessation in dental clinics. To our knowledge this was also the first Swedish study to address use of the smokeless tobacco snus to the same extent as cigarette smoking. Changes in tobacco use between enrolment and follow-up favored the alternative intervention towards usual care for all studied outcomes, with significant effects on the probability to achieve a substantial reduction of tobacco consumption after six months. However, effects were not statistically significant concerning abstinence in the week preceding the survey (primary outcome), prolonged abstinence or quit attempts. Sub-group analyses indicated that the intervention had a higher impact among snus users than among smokers. This study adds to previous evaluations of tobacco cessations in the dental setting in several ways. First, it supports the notion that favorable behavioral changes may be achieved when dentists and dental hygienists devote as little as a few minutes in one session to take up patients' tobacco use in relation to oral health. In fact, evidence from previous studies mostly concerned either intensive or brief but repeated, counseling (Binnie et al., 2007; Hanioka et al., 2010; Nohlert et al., 2009). Our study is generally in line with the very few studies where brief interventions in dentistry were evaluated. Gordon et al. (2010a) found

that a counseling based on the 5A's model was effective in achieving abstinence among smokers, with point prevalence of abstinence 11.3% in the intervention condition after 7.5 months. In a second study by Gordon et al. (2010b) counseling based on 5A's model and a shorter version as 3A's model was evaluated in a sample of smokers and smokeless tobacco users. Both versions were found to be effective in achieving short-term abstinence at 12-month follow-up, but not prolonged abstinence. A possible explanation behind the more modest magnitude and precision of effects in our study compared to the above mentioned studies rests on characteristics of the comparison group. In fact, advice to quit tobacco was provided to some extent also at the control clinics, as it is embedded in the usual praxis followed by all health care providers in Sweden, and this may have concealed weak positive effects of the alternative intervention. It should also be reminded that we evaluated a very brief intervention where pharmacotherapy was suggested but not prescribed. Another explanation could be the motivational stage of the participants, because the majority of the participants in this study were not considering quitting in the short run. Motivation is a predictor of smoking abstinence following an intervention (Yeh et al., 2012). Two previous studies among smokeless tobacco users presented findings very similar to ours. Positive effects were found after three and twelve months by Stevens et al. (1995) in a study evaluating brief counseling in a multi-component intervention. Severson et al. (1998)

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Table 1 Baseline characteristics of the study participants —demographics. Data collected in Sweden in 2012–2013. Control n (%)

Intervention n (%)

Total n (%)

p-value (2-sided)

Gender Female Male

84 (34.7) 158 (65.3)

87 (38.7) 138 (61.3)

171 (36.6) 296 (63.4)

.375a

Age 18–29 30–39 40–49 50–59 60+ mean (SD)

44 (18.2) 27 (11.2) 53 (21.9) 68 (28.1) 50 (20.7) 47.07 (14.83)

55 (24.4) 26 (11.6) 50 (22.2) 55 (24.4) 39 (17.3) 43.95 (14.87)

99 (21.2) 53 (11.3) 103 (22.1) 123 (26.3) 89 (19.1) 45.57 (14.91)

.486a

Education Elementary Secondary Post-secondary

51 (23.6) 128 (59.3) 37 (17.1)

39 (18.6) 133 (63.3) 38 (18.1)

90 (21.1) 261 (61.3) 75 (17.6)

.444a

Occupation Employed Self-employed Not employed

135 (59.7) 22 (9.7) 69 (30.5)

145 (65.3) 19 (8.6) 58 (26.1)

280 (62.5) 41 (9.2) 127 (28.3)

.474a

Civil status Unmarried Married Divorced/separated Widow/widower

113 (50.4) 84 (37.5) 20 (8.9) 7 (3.1)

125 (55.8) 72 (32.1) 19 (8.5) 8 (3.6)

238 (53.1) 156 (34.8) 39 (8.7) 15 (3.3)

.655a

Any chronic disease No Yes

153 (68.3) 71 (31.7)

161 (71.6) 64 (28.4)

314 (69.9) 135 (30.1)

.452a

.024b

Results marked in bold indicate statistical significance at .05 level. a Chi-square statistic. b t-test.

Table 2 Baseline characteristics of the study participants—tobacco use. Data collected in Sweden in 2012–2013. Control n (%)

Intervention n (%)

Total n (%)

p-value

103 (44.0) 115 (49.1) 16 (6.8)

97 (43.1) 103 (45.8) 25 (11.1)

200 (43.6) 218 (47.5) 41 (8.9)

.267a

Duration of tobacco use (years) b5 12 (5.2) 5–10 41 (17.7) 11–20 35 (15.2) 21+ 143 (61.9) Mean (SD) 25.58 (13.99)

15 (6.7) 48 (21.3) 45 (20.0) 117 (52.0) 23.26 (13.99)

27 (5.9) 89 (19.5) 80 (17.5) 260 (57.0) 24.43 (14.02)

.199a

Previous quit attempts 0 35 (15.0) 1–2 68 (29.1) 3+ 131 (56.0)

26 (11.6) 52 (23.1) 147 (65.3)

61 (13.3) 120 (26.1) 278 (60.6)

.122a

Time to first use in the morning ≤5 min 23 (10.2) 6–30 min 104 (46.2) 31–60 min 70 (31.1) 1+ h 28 (12.4)

31 (13.8) 105 (46.7) 62 (27.6) 27 (12.0)

54 (12.0) 209 (46.4) 132 (29.3) 55 (12.2)

.639a

Intention to quit within 6 months 6+ months Time undefined

46 (20.5) 38 (17.0) 140 (62.5)

85 (18.9) 84 (18.7) 280 (62.4)

.513a

20 (4.4) 215 (46.8) 192 (41.8) 32 (7.0) 12.52 (6.92)

.671a

Type of tobacco Only snus Only cigarettes Snus & cigarettes

Amount of tobacco used daily (cigarettes or snus pouches) b5 9 (3.8) 11 (4.9) 5–10 108 (46.2) 107 (47.6) 11–20 103 (44.0) 89 (39.6) 21+ 14 (6.0) 18 (8.0) Mean (SD) 12.42 (6.98) 12.62 (6.88) a b

found that a relatively brief intervention at dental clinics was effective in increasing the likelihood of short-term abstinence among smokeless tobacco users, but not among smokers. Our explanations of the stronger treatment's effect on smokeless tobacco users compared to smokers are very similar to those presented in the cited work by Severson et al. (1998). First, evidence of general health consequences following snus use is still scanty (Scientific Committee on Emerging and Newly Identified Health Risks, 2008), while changes in the oral mucosa caused by its use appear frequently (Roosaar et al., 2006). This could make the cessation advice coming from dental professionals particularly relevant for snus users. For the same reason, personnel in dentistry may feel more self-confident providing cessation advice to smokeless tobacco users, as Severson et al. (1998) also suggest. Considering the almost universal attendance of dentistry clinics in the Swedish population (The National Board of Health Welfare, 2010) it is likely that healthy smokeless tobacco users are reached by advice and counseling on the advantages of quitting tobacco for the first time during a dental visit, while smokers are usually exposed to cessation interventions in multiple health care settings, possibly reducing the additional impact of a single brief counseling. Finally, smokers in Sweden tend to be socially disadvantaged compared to non-users of tobacco or to snus users (Engstrom et al., 2010), and low health-literacy is negatively correlated with successful smoking cessation (Stewart et al., 2013). Strengths and limitations of the study Strengths of this study include the experimental design with wellbalanced participants' characteristics in the trial groups; the very low attrition rate; the careful monitoring of implementation; and the employment of rigorous methods in the statistical analysis. Based on the universal reach of dental care in Sweden, the high participation rate

39 (17.3) 46 (20.4) 140 (62.2)

.078b

.756b

Chi-square statistic. t-test.

among patients, and the eligibility criteria participants seemed to be fairly representative of the tobacco users in the Swedish population (Clevenpalm and Karlsson, 2009). Major weaknesses include lack of blindness and use of self-reported data, rendering the measurement of the outcome not completely reliable, due to the possibility of socially desirable answers in some patients (Murray et al., 1993). Self-reports tend to underestimate tobacco use when compared with biomarkers. However, this underestimation is usually less than 10% (Connor Gorber et al., 2009), and if nondifferential, the estimates of effect would be conservatively biased towards the null value (Rothman, 2008). However, if underreport of tobacco use was higher in the intervention than in the control group, the comparison would spuriously favor the former. Two features of this study speak against a major role of this bias. First, the propensity to give socially desirable answers is affected by the mode of the data collection, being usually lower in self-administered questionnaires compared to interviews (Kreuter et al., 2008; Krumpal, 2013; Tourangeau and Smith, 1996). In this study less than 10% of participants were surveyed with telephone interviews at follow-up. Second, the absence of important program effects among smokers makes it difficult to conceive bias due to under-reporting confined to snus users. There were some violations of the study protocol, for instance in some clinics the failure of screening for eligibility all consecutive patients requiring a visit. Besides, a higher proportion of patients were enrolled with deviating procedures among the control clinics as compared to intervention clinics. However, if the out-of-protocol enrolment resulted in an overrepresentation of highly motivated participants this selection would bias the results in a conservative way, i.e. towards the under-estimation of the intervention's effects. Privately run clinics were underrepresented in this study, while they serve about half of adults seeking dental care (The National Board of

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Table 3 Odds ratios and 95% CI of abstinence, reduction of tobacco consumption and quit attempts according to intervention condition. Data collected in Sweden in 2013.

7-day abstinence 3-month abstinence 50% reduction Quit attempts

Control with the outcome/number analyzed

Intervention with the outcome/number analyzed

OR (95%CI)a unadjusted

OR (95%CI)a adjusted for ageb

14/233 8/233 32/225 100/233

18/219 11/219 56/219 111/219

1.40 (0.68–2.89) 1.49 (0.59–3.77) 2.07 (1.28–3.35) 1.37 (0.94–2.00)

1.43 (0.69–2.96) 1.46 (0.57–3.72) 2.09 (1.28–3.39) 1.30 (0.89–1.91)

Results marked in bold indicate statistical significance at .05 level. a Reference category: control condition. b Continuous variable.

Health Welfare, 2010). However, this selection would possibly reflect on the intervention implementation, rather than on its effects. Intervention implementation is a particularly important feature to be considered at a later stage, i.e. when planning a large diffusion of an intervention (Victora et al., 2004). In fact, if staff and organization at the participating clinics would be selected to be particularly committed to tobacco cessation the population impact in dissemination stage would be lower than anticipated from trial data. The current study is the first evaluation of brief counseling at dental clinics for tobacco cessation conducted in Sweden. Although the intervention did not show significant effects in promoting complete abstinence from tobacco it had promising effects in promoting a substantial reduction in consumption. Studies support the hypothesis that gradual reduction of tobacco use predicts later complete cessation to the same extent as an abrupt quit attempt (Lindson-Hawley et al., 2013). As additional original feature, this study explored the effectiveness of a brief counseling in dentistry separately among Swedish smokers and among users of the smokeless tobacco snus. With caveat for the limitations of subgroup analyses, the observation of stronger intervention effects in this latter group may convey useful lessons. First, it suggests that brief counseling should focus on the specificity of a given professional role in preventing tobacco-related health problems, rather than adopting a generalized risk-warning approach. Subsequent development of the brief counseling model to enhance its effectiveness on smoking behavior should take this aspect in deeper account. Second, brief structured counseling in dentistry may emerge as an easy applicable new strategy in tobacco control activities, since effective cessation programs for smokeless tobacco users are relatively rare.

Conclusion Patients in dental care receiving a very brief structured counseling for tobacco cessation reported generally more favorable changes in tobacco use compared to patients exposed to usual care, with a significant effect on reduction of tobacco consumption. The intervention seemed to promote behavioral changes particularly among snus users. These results should be replicated in future studies with longer follow-up time.

Conflict of interest statement The work of Maria R. Galanti, Suvi Virtanen and Izla Rohyo was supported by grant awarded by the National Board of Health and Welfare (contract grant nr. 2.4-43860/ 2011). The work of Zangin Zeebari was due as part of his employment at the Centre for Epidemiology and Community Medicine, Stockholm County Council. The funding agencies had no role in study design; collection, analysis, and interpretation of data; writing the report; and the decision to submit the report for publication. The authors declare that there are no conflicts of interest. No financial disclosures were reported by the authors of this paper.

Trial registration The trial was registered in the ISRCTN Register of controlled trials with identification number ISRCTN50627997, in date August 28, 2012. The FRITT study was funded by the National Board of health and Welfare (contract grant nr. 2.4-43860/2011). The study was approved by the Ethical Review Board of Stockholm Region in date March 15, 2012 (nr. 2012/237-31/5).

Table 4 Odds ratios and 95% CI of abstinence, reduction of tobacco consumption and quit attempts according to intervention condition, among smokers and snus users. Data collected in Sweden in 2013. Smokersb

7-day abstinence 3-month abstinence 50% reduction Quit attempts

Control with the outcome/number analyzed

Intervention: with the outcome/number analyzed

OR (95%CI)a unadjusted

OR (95%CI)a adjusted for aged

9/109 5/109 18/109 58/109

8/100 4/100 27/100 53/100

0.97 (0.36–2.61) 0.87 (0.23–3.33) 1.87 (0.96–3.66) 0.99 (0.57–1.71)

1.03 (0.38–2.82) 0.86 (0.22–3.31) 1.85 (0.94–3.62) 0.94 (0.54–1.63)

Snus usersc

7-day abstinence 3-month abstinence 50% reduction Quit attempts

Control: with the outcome/number analyzed

Intervention: with the outcome/number analyzed

OR (95%CI)a Unadjusted

OR (95%CI)a Adjusted for aged

4/100 2/100 12/100 29/100

9/94 7/94 25/94 40/94

2.54 (0.76–8.54) 3.94 (0.80–19.48) 2.66 (1.25–5.66) 1.82 (0.99–3.32)

2.48 (0.74–8.39) 3.92 (0.79–19.46) 2.79 (1.30–6.00) 1.69 (0.90–3.15)

Results marked in bold indicate statistical significance at .05 level. a Reference category: control condition. b Includes exclusive smokers. c Includes exclusive snus users. d Continuous variable.

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