Participants
Smoking parents were recruited through primary schools across several municipalities in the Netherlands. Primary schools were contacted by research assistants and were asked to distribute study invitation letters to parents. To increase the participation rate of schools, demands on schools were kept to a minimum (i.e., schools were asked to give the study invitation letters to the children and children were requested to give the letters to their parents). A total of 890 primary schools were contacted and 438 schools (49.2%) agreed to participate. In total, approximately 35,000 study invitation letters were mailed to schools. For the present study, schools were asked to give the letters only to children aged 9–12 years (Dutch grade 6–8; US grade 4–6). Study invitation letters included information about the study and eligibility criteria. Parents registered for the study by returning a form with their contact information in an enclosed envelope. Registration was also possible via e-mail, via telephone, or via the study website. Inclusion criteria were: 1) being at least a weekly smoker, 2) being a parent/caretaker of a child between 9–12 years old, 3) having the intention to quit smoking (currently or in the future), and 4) giving informed consent for participation of parent–child dyad. A total of 622 parents registered for the present study. A total of 512 parents were enrolled in the present study (returned informed consent form and baseline questionnaire).
Procedure
An overview of the study design is presented in Figure 1. The baseline measurement took place between January and July 2011. Parents and children were asked to individually fill out a questionnaire (via a website or on paper). For the present study, only the parent data were used. More detailed information regarding the use of the child data can be found in the study protocol [32]. After the baseline assessment, parents were randomly assigned to either the telephone counselling condition (n=256) or the self-help brochure condition (n=256). A computer program was used to generate a randomization schedule. Allocation of participants to trial conditions was done by a member of the research group who was not involved in the present study. Participants were stratified by gender, educational level, and smoking intensity. Within 2 weeks after baseline assessment, parents were either called to schedule the first counselling call or they received the self-help brochure. The post-measurement took place approximately three months after start of the intervention (i.e., receiving the intake call or the self-help brochure). Further details on the study methodology can be found in the study protocol [32]. Parent–child couples received an incentive of 100 euro (approximately 127 US dollars) for their participation in all assessments. The ethics committee of the Faculty of Social Sciences at the Radboud University Nijmegen approved of the study.
Conditions
Proactive telephone counselling
Participants in the telephone counselling condition received up to seven counsellor-initiated phone calls (i.e., one 30-minute intake call and up to six additional 10-minute calls) across a period of approximately three months. Telephone counselling was based on Motivational Interviewing [33] and cognitive-behavioural skill building. Counselling calls were conducted by counsellors of STIVORO, the non-profit Netherlands national quitline. All counsellors were trained and experienced in the delivery of telephone counselling.
During the intake call, the participants were asked if they wanted to set a quit date. Participants who wanted to set a quit date were encouraged to set a quit date within 10–12 days following the intake call. Subsequently, up to six additional phone calls were offered to support the initiation and maintenance of abstinence (Figure 1). Emphasis was put on psycho-education, intrinsic motivation for behavioural change, behavioural support, and relapse prevention. Participants who were not willing to set a quit a date were offered up to two additional phone calls (Figure 1). Emphasis was put on exploring ambivalence and increasing the participant’s intrinsic motivation to quit smoking using Motivational Interviewing [34]. If participants during any one call indicated that they wanted to set a quit date, they were offered additional phone calls to support the initiation and maintenance of abstinence.
In addition to the counselling calls, all participants in the telephone counselling condition received three accompanying booklets (4 pages, colour-print), which were designed specifically for the present study. Each booklet contained didactic information, tips and advice on how to initiate and maintain abstinence, motivational or self-efficacy enhancing messages, as well as ‘parent-relevant information’ (e.g., effects of SHS on children, suggestions to involve children in process of smoking cessation, strategies to manage parent-specific stressors). Participants received the booklets at three time points throughout telephone counselling (immediately after start of telephone counselling, three weeks after start of telephone counselling, and six weeks after start of telephone counselling).
Self-help brochure
Participants in the self-help condition received a 40-page, colour-printed self-help brochure a for smoking cessation copyrighted by Stivoro. The brochure included didactic information on nicotine dependence and the health benefits associated with quitting smoking, tips and advice on how to initiate and maintain abstinence, instruction in the use of cognitive and behavioural skills to avoid triggers to smoke and cope with urges to smoke, and strategies for managing a lapse or relapse to smoking. The brochure was divided into five parts: reasons for quitting, craving and withdrawal, preparing to quit, help with quitting, and maintenance of abstinence. The brochure was based on empirically supported practices for advice on smoking cessation, such as psycho-education, advice, tips, and exercises [31].
Measures
Baseline characteristics
The baseline questionnaire included the variables gender, age, nationality, education, material status, employment status, cigarettes per day, years of smoking, nicotine dependence [FTND; [35], ever made a quit attempt and quit attempt in the past 12 months [36], intention to quit [8], other household smokers, and selected smoking-related illnesses of parent and child (e.g., cardiovascular disease, chronic respiratory illness).
Use and acceptability of cessation support
Telephone counselling condition
Participants in the telephone counselling condition were asked to report how many counselling calls they received (0, 1, 2, 3, 4, 5, 6, 7, 8 or more). Participants who received at least one counselling call were asked to which degree the call(s) helped with (1) motivation to quit or to stay quit, (2) coping with withdrawal symptoms, (3) coping with craving, (4) coping with situations that trigger craving, (5) prevention of a lapse or relapse, and (6) motivation to try again after a lapse or relapse. Ratings were: didn’t help, helped a little, and helped a lot. In addition, participants indicated to which degree they received emotional support and practical tips from the counsellors. Ratings were: not at all, a little, a lot. Also, participants were asked whether they had tried tips suggested during counselling (none, a few, a lot). Finally, participants indicated their satisfaction with the length of the intervention (too short, about right, too long), their overall satisfaction with telephone counselling (very unsatisfied, unsatisfied, satisfied, very satisfied), and whether they would make use of the STIVORO quitline again (no, yes).
Also, participants in the telephone counselling condition were asked how many accompanying booklets they received (0, 1, 2, 3). Recipients were asked to which extent they read the booklets (none or very little, less than half, more than half, in full) and whether they used tips provided in the booklets (none, a few, a lot). Also, recipients were asked to indicate to which extent the booklets helped with varying areas of difficulties and their overall satisfaction with the booklets (see above).
Self-help brochure condition
Participants in the self-help material condition were asked whether they received a brochure (yes, no). Recipients were asked to which extent they read the brochure (none or very little, less than half, more than half, in full) and whether they tried tips suggested in the brochure (none, a few, a lot). To evaluate acceptability of the brochure, recipients were asked the same questions about the brochure as participants in the telephone counselling condition were asked about the counselling calls (i.e., the extent the brochure helped with varying areas of difficulties, the extent to which participants received emotional support and practical tips, satisfaction with the length of brochure, overall satisfaction with brochure).
Strategy for analysis
Participant characteristics at baseline are presented. To determine whether the randomization resulted in an equal baseline distribution of participant characteristics across conditions, chi-square tests and t-tests for independent samples were conducted. Use and acceptability of cessation support in both conditions are summarized. Differences between the two conditions in acceptability of cessation support were examined using chi-square tests. Post-measurement data are presented for recipients-only as well as for the intention-to-treat population. Statistical testing and report of results pertain to the intention-to-treat population.
Attrition
At post-measurement, 229 participants (89.5%) completed the questionnaire in the telephone counselling condition and 246 (96.1%) completed the questionnaire in the self-help brochure condition. Attrition was significantly higher in the telephone counselling condition than the self-help brochure condition (χ
2 = 8.42, p=.004). Participants lost at post-measurement were compared with the remaining participants on age, gender, education, number of cigarettes smoked per day, nicotine dependence, and intention to quit. In the entire sample, participants lost at post-measurement did not differ significantly from the remaining participants on any of these variables. In the telephone counselling condition, participants lost at post-measurement smoked significantly more cigarettes per day at baseline (M=18.8, SD=11.3) compared to the remaining participants (M=15.4, SD=7.5, t=1.99, p=.05). No other differences were found on the assessed variables.