With the support of the president of the Massachusetts Building Trades Council, the study team introduced the study at a meeting for the 28 training program directors. Later, we mailed each director a recruitment packet that explained the study and its requirements, and made follow-up phone calls to assess willingness to participate, then scheduled an in-person meeting as appropriate.
To be eligible for the study, training programs had to: (1) be located within 1 h of the study base (DFCI), (2) enroll a minimum of 40 apprentices, (3) agree to random assignment as to start date of intervention, (4) allow for survey administration to take place during class time in the union hall, and (5) allow for each of the intervention components to take place at the union hall. Of the 20 programs that initially met eligibility criteria, 10 refused to participate because they could not accommodate the length of the intervention (n = 6) or had an existing smoking cessation program (n = 4). Ten eligible sites agreed to be part of the study and were size matched and randomly assigned to four intervention sites (n = 1,044 trainees) and six control sites (n = 897 trainees). All apprentices at the intervention sites were eligible to participate in the study.
The Dana-Farber Cancer Institute institutional review board approved all the methods and materials used in the study. We obtained survey data at all sites through written questionnaires that we administered at baseline (time 1), followed by a 4-month intervention period in the intervention sites. Follow-up surveys were administered 1 month (time 2) and at least 6 months (time 3) after the intervention. All surveys were administered during regularly scheduled meetings or class times at the union halls. At each study period, study staff surveyed all apprentices who were present. Questionnaires were left with apprenticeship program coordinators who then handed or mailed these questionnaires (with stamped return envelope) to apprentices who were absent at survey times.
At baseline (time 1), 1,817 apprentices (93.6% response rate) filled out the study questionnaire. After the intervention, we were able to match 1,502 apprentices (82.6% response rate) at time 2 and 1,362 apprentices (80.7% response rate) at time 3 to baseline surveys. The sample for the present analyses is restricted to the embedded cohort of 1,213 apprentices for whom we had survey data for all three time points of the study. Data collection at time 3 occurred at least 6 months and up to 9 months after the intervention due to the rigidity of the training schedules for the apprentices which prevented data collection at scheduled times. Two intervention sites had data collection at 8 and 9 months after the intervention.
Intervention study conditions
The apprentices in the intervention sites received a multi-pronged intervention, which followed the social contextual framework by integrating occupational concerns into intervention activities. The intervention was based on the US Public Health Service treatment guidelines for tobacco use and dependence . Also, we drew from materials and approaches of Building Trades United to Ignite Less Tobacco (BUILT)—a project of the Labor Occupational Health Program at the University of California, Berkeley and the state building and construction trades council of California .
The intervention components were also pilot-tested to confirm their feasibility and to establish estimates for likely effect sizes . Qualitative research conducted as part of the pilot study indicated that apprentices were well aware of the harmful health effects of smoking, and uninterested in hearing this generic message. In contrast, as apprentices learning their new trades, they expressed great interest in new and more personally relevant information, such as how the new substances and processes they were learning would affect their health, especially if they continued to smoke. Guided by the social contextual framework, a key goal of the intervention curriculum was to increase the apprentices’ awareness of the potential additive and synergistic effects of exposure to job-related hazards combined with smoking. In essence, the apprenticeship period constituted a new ‘teachable’ moment for smoking cessation.
The multi-pronged intervention was conducted over 4 months and consisted of the following components.
Toxics and tobacco curriculum We supplemented the curriculum of the apprenticeship programs to include two 1-h modules that focused on job hazards encountered in the building trades, stressing the potential additive and synergistic effects of these exposures, and cigarette smoking. During a class session, the apprentices were shown a video, made by the California BUILT project, which reinforced these messages and used humor and sarcasm that resonated with the occupational culture of building trades workers. And, study staff let the apprentices know that the team would be offering smoking cessation ‘classes,’ i.e., group-based behavioral counseling, at their union halls in the coming weeks.
Group-based behavioral counseling State certified tobacco treatment specialists trained in motivational interviewing techniques led 8-weekly group counseling sessions at each intervention site. Groups ranged in size from 3 to 12 participants. Topics covered included pros and cons of tobacco use and quitting, potential barriers and triggers, reasons to quit, coping techniques, preparing for withdrawal, proper use of over-the-counter nicotine replacement therapy (NRT) and options for prescription medications to assist with quitting, stress management, and how to stay quit.
Nicotine replacement therapy Smoking cessation counselors made NRT patches (21 mg—Step 1, 14 mg—Step 2 and 7 mg—Step 3) available free of charge to smokers at the intervention sites regardless of their level of participation in the behavioral therapy group sessions as long as they were deemed by one of the project’s smoking cessation counselors to have no contraindications for NRT.
Do it yourself quit kit These kits, which contained smoking cessation guide, were available to all apprentices.
Environmental cues for smoking cessation The study team created and displayed in apprenticeship classrooms and common areas a series of five posters that reinforced key concepts in the Toxics and Tobacco curriculum modules and that included photos and quotes from apprentices who had recently quit smoking about why and how they quit. In addition, written materials, which addressed how co-workers, friends and family members can support quit attempts, were provided to apprentices at intervention sites.
Apprentices who chose to attend the cessation classes were given early release from apprenticeship classes and meals were provided at the sessions. Apprentices who completed at least seven of eight counseling sessions were eligible to participate in a raffle drawing for a cash prize. Also, we provided incentives in the form of $10 store gift cards for completion of surveys.
The control sites participated in all surveys but did not receive any intervention components. We delivered the intervention to these sites after we had collected all study data.
Apprentices who reported smoking at least 100 cigarettes in their lifetimes and smoking in the last 30 days were classified as current smokers at baseline. We collected several measures of smoking cessation as recommended by a Society for Research on Nicotine and Tobacco workgroup on measures of smoking abstinence . We measured prolonged abstinence from smoking for at least 6 months from the time of data collection at time 3 (primary study outcome). Also, we measured 7-day point prevalence abstinence at 1-month post-intervention (time 2; Question: Have you smoked a cigarette, even a puff, in the last 7 days). We assessed intention to quit in the next 30 days and next 6 months, smoking decisional balance , self efficacy , smoking intensity (number of cigarettes smoked per day in the last 30 days), smoking frequency (number of days smoked in the last 30 days), and confidence in staying quit (options: have not quit, extremely confident, very confident, somewhat confident, slightly confident, and not confident). Based on answers at times 2 and 3, we created new variables that summarized changes in smoking intensity, smoking frequency, decisional balance and confidence in staying quit as either increase, decrease, or no change.
Apprentices self-reported their race/ethnicity, age, educational attainment, gender, and income in the baseline survey. We collapsed race/ethnicity into Hispanic, Black, White, and Other. Likewise, educational attainment was collapsed from seven categories into four (less than high school, high school or GED, some college or 2 year degree, or 4 years or more). The less than high school and high school or GED categories were further collapsed into one category during data analysis because only four people reported having less than high school education. We also collapsed household income from seven $10,000 increments of income from under $10,000 to $75,000 or more into four categories (<$25,000, $25,000–49,999, $50,000–74,999, and ≥$75,000).
We assessed smoking behaviors via self-report on surveys, and opted not to conduct biochemical verification. Drug testing is routine in the study sites, and union leaders advised us that any biological tests would likely be misinterpreted by workers as a drug test, and would likely lead to deep mistrust of study staff. To ensure accurate reporting of smoking status, survey assistants stressed the importance of truthful reporting of smoking status to the ability of the team to develop effective smoking cessation interventions. They also reminded participants that confidentiality of results would be maintained.
In this study, apprentice sites were the unit of randomization and intervention while individual apprentices were the unit of measurement. Our analysis involved the apprentices who met our baseline criteria for smoking. Using the intention to treat principle, we classified all apprentices in the intervention sites as part of the intervention group regardless of their level of participation and compliance. Due to the potential within-cluster (site) correlation, all multivariate analyses were conducted using SAS GLIMMIX with sites being modeled as random effect terms .
Data analysis began with univariate descriptive analyses using chi-square statistics for categorical and t-test for normal continuous variables. For the primary outcome, we first evaluated smoking cessation rates between the intervention and control groups using two-by-two contingency tables. We modeled multivariate odds of smoking cessation at times 2 and 3 comparing the intervention to control group controlling for demographic variables. To assess increase, decrease, or no change in secondary variables, we constructed multivariate multinomial logistic regression models using SAS GLIMMIX controlling for demographic variables. For those who did not report their ages (n = 48), we assigned them the median age at their union site. To account for those missing income (n = 185), race (n = 74), education (n = 62), and gender (n = 29), we used the Amelia II program, a bootstrapping-based algorithm that “multiply imputes” missing data in a cross-sectional or longitudinal setting (freely available from http://gking.harvard.edu/amelia/), to impute data for those missing these variables . We used the MIANALYZE procedure in SAS to combine the results of the multivariate regressions from 10 imputations.