Design

SCPW is funded by the Tobacco and Alcohol Control Office, Department of Health of Hong Kong SAR government, and organized by the Lok Sin Tong Benevolent Society, Kowloon (LST) in Hong Kong. Briefly, invitations were sent to companies selected from the list of companies (in alphabetic order) of the Care Company Scheme in Hong Kong or which had a good collaborating history with LST to initialize recruitments for SCPW-Phase II in 2015. Smoking employees of the participating companies were invited to attend a 1-hour health talk on smoking hazards, benefits of quitting, and methods to quit. Eligible participants were Chinese-speaking Hong Kong residents aged ≥18 years, smoking at least 1 cigarette per day, and staying in Hong Kong for the coming 12 months. They were invited to participate in the program after the health talk. All 725 participants received a 32-page self-help booklet at baseline and 15 text messages in the following 3 months (Supplementary file Table 1). They chose to join one of the three intervention groups (Group A: intensive counselling, n=22; Group B: brief face-to-face counselling, n=21; Group C: no additional intervention, n=523) after the health talk. Participants recruited individually (e.g. through booths in the community) or not available to attend the health talk joined Group D (n=159), which included telephone counselling as the key intervention. All participants provided written consent and were informed that they could withdraw from the program at any time without any interest loss.

The SCPW program also promoted workplace support for SC by organizing internal meetings with employers or managerial staff (hereafter as ‘employers’), which was assessed after completing the program. We invited employers to complete a company-level questionnaire as they were considered to be better aware of the company’s SC related policy and support than employees³. Fifty (of all 90 participating companies, 55.6%) companylevel questionnaires were completed. Only 383 Group C participants who could be matched with the 39 (of 50 completed, 78.0%) company-level questionnaires were included in the present analysis (Figure 1). Group D participants were excluded because information on workplace SC support was not available. We also excluded Group A and B participants (small sample size) because of different interventions (vs Group C) to avoid the potentially different effects from different interventions. The baseline characteristics of Group C participants included in the present analysis were comparable with the excluded Group A, B, D and C (Supplementary file Table 2).

Figure 1

Sample selection procedure

Measures

Participants self-administered the baseline questionnaire before the health talk. The measures included cigarette consumption and nicotine dependence, past quit attempt (yes/no), intention to quit (within 7 days/30 days/6 months/undecided), perceptions of quitting (importance, confidence, difficulty) were assessed on a scale of 0–10; higher scores indicating greater level⁹), and sociodemographic characteristics (sex, age, marital status, education level, and monthly household income). Nicotine dependence was assessed by the Heaviness of Smoking Index (HSI)¹⁰. HSI sums up the scores of 2 questions: the number of cigarettes smoked per day (0: 1–10; 1: 11–20; 2: 21–30; 3: >31) and time to the first cigarette after waking (0: after 60 minutes; 1: in 31–60 minutes; 2: in 6–30 minutes; 3: within 5 minutes). Higher scores indicate higher nicotine dependence. The total scores of HSI ≤2, 3–4, and 5–6, indicate low, moderate, and high levels of nicotine dependence, respectively. Telephone follow-up was conducted at 1 week, and at 1, 3, 6, and 12 months, after baseline to assess smoking cessation outcomes. In the present study, the main outcome was self-reported past 7-day point prevalence abstinence (PPA) at follow-up at 6 months.

Based on SCPW-Phase I outcomes and with further refinement according to the employers’ and SC experts’ comments, we designed one tool to measure workplace SC support by 14 types of support under three domains: providing incentives for successful quitters, providing support for SC attempts/actions, and smoke-free environment support (Supplementary file Table 3). Each type of SC support had a yes/no response. Affirmative responses were summed to derive a score of 0–14, with higher scores indicating greater workplace SC support. Specifically, providing incentives for successful quitters included cash, holidays, gifts, and public praises, with scores ranging from 0–4. Providing support for SC attempts/actions included paid time off for attending SC workshops, offering free healthy snacks in the pantry to replace smoking breaks, organizing sharing sessions on successful quitting experiences, and offering reimbursement for joining exercise programs/classes, with scores ranging from 0–4. Smoke-free environment support included email, notice, posters, other circulation on smoke-free information, setting desktop/screen saver as smoke-free logo, signing ‘Smoke-free contact’ with employees, setting up ‘Smoke-free workplace’ committee, posters on successful quitting cases, organizing ‘smoke-free slogan’ competition, with scores ranging from 0–6. We did not include employer-offered insurance coverage on SC treatment as it was rarely provided, and SC treatments are free in Hong Kong.

Company size was categorized by the number of personnel into: small (≤10), medium (11–100), and large (≥100). Occupation types were recoded based on the Standard Occupational Classification (SOC) system and then classified into white-collar, blue-collar, and services¹¹.

Statistical analysis

Stata 15.1 (Stata Crop LP, College Station, TX, USA) was used. Multivariable logistic regressions yielded adjusted odd ratios (AORs) for self-reported past 7-day PPA at follow-up at 6 months by the level of workplace SC support [overall workplace SC support (0–14) and each of the three domains: providing incentives for successful quitters (0–4), providing support for SC attempts/actions (0–4), and smoke-free environment support (0–6)] and participants’ baseline characteristics (sex, age, company size and type, intention to quit, nicotine dependence, and perceptions of quitting). We used multiple imputation by chained equation to impute missing values in self-reported past 7-day PPA at follow-up at 6 months and participants’ baseline characteristics under the missing-at-random assumption¹². Multiple imputation is a commonly used approach to handle missing data by creating several (n=50) imputed datasets and combining results from analyses in each imputed dataset following Rubin’s rule¹³. The imputation model was based on variables included in the main analysis and additional ones that are predictors of quitting in the literature. Including these variables in the imputation model would lower the chance of violating the missing-at-random assumption, increase statistical power (large sample size), and reduce selection bias. To test if the association between overall workplace SC support and self-reported past 7-day PPA at follow-up at 6 months was modified by subgroups (i.e. sex, age, quit intention, nicotine dependence, company size, and company type), average marginal effects (AMEs)¹⁴ by subgroups were calculated. AMEs are the changes in participants’ predicted probability of self-reported past 7-day PPA at 6 months in relation to per score change in overall workplace SC support. A significant difference in AMEs between subgroups of a characteristic (e.g. male vs female) suggests effect modification.

Workplace SC support: qualitative interviews of employers

After completing the SCPW program, we individually interviewed 9 employers from different companies (5 from the property management industry) using a semi-structured interview guide. Characteristics of the interviewees are given in Supplementary file Table 4. The interviews aimed to explore employers’ perspectives and experience with the program, including providing workplace SC support. In the present study, we only presented results related to providing workplace SC support. Interviewees were first asked to describe the workplace SC support they had provided. Their perspectives and experiences of providing workplace SC supports were further explored using open-ended questions (e.g. ‘What factors would you consider when deciding to provide workplace SC support?’, ‘What were the difficulties of providing workplace SC support?’).

All interviews were audio-recorded and transcribed verbatim. Thematic analysis described by Braun and Clarke¹⁵ was done. Researcher (ZG) read all transcripts carefully to generate preliminary thoughts on the data, then coded the passages related to the question. Codes that shared similar meanings were collated as initial themes. After reviewing and refining these initial themes, the final themes were defined and named.

Quantitative results

Table 1 shows that 94.0% of participants (n=383) were male, 29.0% were aged ≥50 years, and 62.1% were married or cohabiting. Most participants had secondary education (60.3%), and 44.9% had a monthly household income of HK$30000 or above (US$1=HK$7.8). On average, participants smoked for 17.80 years (SD=9.92) and 14.90 cigarettes (SD=17.35) per day. Most participants had light (53.9%) or moderate (41.8%) levels of nicotine dependence. A quarter of participants had never made quit attempts before, and 79.8% had no intention to quit. Participants perceived moderate importance (6.63 ± 3.05), confidence (5.68 ± 2.98), and difficulty (6.11 ± 3.11) of quitting.

Table 2 shows that 91.9% of participants worked in large companies; 56.9% were blue-collar workers, and 40% were white-collar workers. The mean score of the overall workplace SC support was 2.30 ± 1.68 (out of 14). The mean score for providing an incentive to successful quitters, providing support for SC attempts/actions, and smoke-free environment support was 0.14 ± 0.44 (out of 4), 0.91 ± 0.71 (out of 4), and 1.25 ± 0.91 (out of 6), respectively. Nearly all (95.8%) participants were offered one or more smoke-free environment supports, 74.2% were offered one or more supports for SC attempts/actions, but only 10.2% were offered one or more incentive supports.

The self-reported past 7-day PPA at follow-up at 6 months was 20.9% (80/383). Table 3 shows that greater workplace support was associated with self-reported past 7-day PPA at follow-up at 6 months (overall: AOR=1.32; 95% CI: 1.08–1.61; support for SC attempts/actions: AOR=1.93; 95% CI: 1.21–3.07, smoke-free environment support: AOR=1.51; 95% CI: 1.08–2.11).

Table 3 also shows that participants with intention to quit within 30 days were associated with self-reported past 7-day PPA at 6 months with AORs ranging from 2.78 to 2.98 (all p<0.05). Participants with higher quitting confidence reported higher odds of self-reported past 7-day PPA at 6 months (AOR: 1.19 to 1.22, all p<0.05).

We found a moderate but insignificant association between providing incentives for successful quitters and self-reported past 7-day PPA at 6 months (AOR=1.59; 95% CI: 0.60–4.21). No effect modification by sex, age group, intention to quit, nicotine dependence, company size, or occupation type were observed (Table 4).

Qualitative results

We identified three themes from interviews with employers: 1) establish a good company image; 2) cost-benefit consideration; and 3) lacking SC knowledge as a barrier to providing workplace SC support.

Most interviewees reported that they were willing to provide workplace SC support because they wanted to establish a good company image:

‘The reason for providing workplace SC support was company image. We can’t let customers see our colleagues smoking on the streets.’ (Interviewee 8, male, aged 35 years, from sales industry)

Interviewees reported the cost-benefit consideration when deciding to provide which types of workplace SC support. They preferred to provide types of support that are beneficial but cost less. Some interviewees reported that providing incentives required the directors to approve the budget, which depended on their perceived benefits of helping smoking employees quit:

‘We are customer severing industry. We need to consider whether providing the workplace SC support would affect our service. If the workplace SC support would not cost much time but improve our service, we would provide (workplace SC support).’ (Interviewee 9, male, aged 37 years, from property management industry)

‘Providing incentive involved budget, which was depended on if directors thought SC was important.’ (Interviewee 5, female, from property management industry)

Interviewees also reported a lack of professional SC-related knowledge was the barrier to providing workplace SC support:

‘It was difficult for us to design workplace SC programs to help employees to quit because we were not experts of SC, we lacked the professional knowledge and didn’t know what should do.’ (Interviewee 9, male, aged 37 years, from property management industry)

Limitations

This study had some limitations. First, employers and smoking employees who joined the SCPW may be more concerned about smoking, which might limit the generalities of our findings. Second, most participants were male. But it was consistent with a much higher smoking prevalence in males (16.7%) than in females (3.0%) in Hong Kong⁶. Third, lack of biochemical validation for quitting might result in over-reporting of successful quit. Fourth, workplace SC support in our study was reported by employers, and employees might not receive or be aware of this support provided by the workplace. The agreement between employers’ and employees’ reported workplace support and associations between employees’ self-reported and objectively validated workplace SC support and smoking abstinence should be further studied. Lastly, our outcome was mainly based on large size companies’ information on workplace SC support, where the priority of workplace tobacco control was different from small companies²⁵. Further study in different sizes of companies to assess the effect of workplace SC support is warranted.