Modeling missing binary outcome data in a successful web‐based smokeless tobacco cessation program

Aim To examine various methods to impute missing binary outcome from a web‐based tobacco cessation intervention. Design The ChewFree randomized controlled trial used a two‐arm design to compare tobacco abstinence at both the 3‐ and 6‐month follow‐up for participants randomized to either an enhanced web‐based intervention condition or a basic information‐only control condition. Setting Internet in the United States and Canada. Participants Secondary analyses focused upon 2523 participants in the ChewFree trial. Measurements Point‐prevalence tobacco abstinence measured at 3‐ and 6‐month follow‐up. Findings The results of this study confirmed the findings for the original ChewFree trial and highlighted the use of different missing‐data approaches to achieve intent‐to‐treat analyses when confronted with substantial attrition. The use of different imputation methods yielded results that differed in both the size of the estimated treatment effect and the standard errors. Conclusions The choice of imputation model used to analyze missing binary outcome data can affect substantially the size and statistical significance of the treatment effect. Without additional information about the missing cases, they can overestimate the effect of treatment. Multiple imputation methods are recommended, especially those that permit a sensitivity analysis of their impact.     

Happy ending: a randomized controlled trial of a digital multi-media smoking cessation intervention

AIMS: To assess the long-term efficacy of a fully automated digital multi-media smoking cessation intervention. DESIGN: Two-arm randomized control trial (RCT). Setting World Wide Web (WWW) study based in Norway. PARTICIPANTS: Subjects (n = 396) were recruited via internet advertisements and assigned randomly to conditions. Inclusion criteria were willingness to quit smoking and being aged 18 years or older. INTERVENTION: The treatment group received the internet- and cell-phone-based Happy Ending intervention. The intervention programme lasted 54 weeks and consisted of more than 400 contacts by e-mail, web-pages, interactive voice response (IVR) and short message service (SMS) technology. The control group received a self-help booklet. Additionally, both groups were offered free nicotine replacement therapy (NRT). MEASUREMENTS: Abstinence was defined as 'not even a puff of smoke, for the last 7 days', and assessed by means of internet surveys or telephone interviews. The main outcome was repeated point abstinence at 1, 3, 6 and 12 months following cessation. FINDINGS: Participants in the treatment group reported clinically and statistically significantly higher repeated point abstinence rates than control participants [22.3% versus 13.1%; odds ratio (OR) = 1.91, 95% confidence interval (CI): 1.12-3.26, P = 0.02; intent-to-treat). Improved adherence to NRT and a higher level of post-cessation self-efficacy were observed in the treatment group compared with the control group. CONCLUSIONS: As the first RCT documenting the long-term treatment effects of such an intervention, this study adds to the promise of digital media in supporting behaviour change.     

Effectiveness of a stepped primary care smoking cessation intervention: cluster randomized clinical trial (ISTAPS study)

Aim To evaluate the effectiveness in primary care of a stepped smoking cessation intervention based on the transtheoretical model of change. Design Cluster randomized trial; unit of randomization: basic care unit (family physician and nurse who care for the same group of patients); and intention‐to‐treat analysis. Setting All interested basic care units (n = 176) that worked in 82 primary care centres belonging to the Spanish Preventive Services and Health Promotion Research Network in 13 regions of Spain. Participants A total of 2827 smokers (aged 14–85 years) who consulted a primary care centre for any reason, provided written informed consent and had valid interviews. Measurements The outcome variable was the 1‐year continuous abstinence rate at the 2‐year follow‐up. The main variable was the study group (intervention/control). Intervention involved 6‐month implementation of recommendations from a Clinical Practice Guideline which included brief motivational interviews for smokers at the precontemplation–contemplation stage, brief intervention for smokers in preparation–action who do not want help, intensive intervention with pharmacotherapy for smokers in preparation–action who want help and reinforcing intervention in the maintenance stage. Control group involved usual care. Among others, characteristics of tobacco use and motivation to quit variables were also collected. Findings The 1‐year continuous abstinence rate at the 2‐year follow‐up was 8.1% in the intervention group and 5.8% in the control group (P = 0.014). In the multivariate logistic regression, the odds of quitting of the intervention versus control group was 1.50 (95% confidence interval = 1.05–2.14). Conclusions A stepped smoking cessation intervention based on the transtheoretical model significantly increased smoking abstinence at a 2‐year follow‐up among smokers visiting primary care centres.     

Smoking cessation intervention in parents of young children: a randomised controlled trial

OBJECTIVE: To examine whether telephone counselling based on the stages of change component of Transtheoretical model of behaviour change together with educational materials could help non-motivated smoking parents of young children to cease. DESIGN: Randomised controlled trial. SETTING: Hong Kong Special Administrative Region, PR China. PARTICIPANTS: 952 smoker fathers and mothers of Chinese children aged 5 years. INTERVENTION: Participants were randomly allocated into two groups: the intervention group received printed self-help materials and three-session telephone-based smoking cessation counselling delivered by trained counsellors; the control group received printed self-help materials only. A structured questionnaire was used for data collection at baseline and at 1, 3 and 6 month follow up. MAIN OUTCOME MEASURES: The main outcome is 7 day point prevalence quit rate at 6 months (defined as not smoking during the 7 days preceding the 6 month follow up) determined by self reports. Other secondary outcomes were self reported 24 h point prevalence quit rate and self-reported continuous quit rate and bio-chemically validated quit rate at 6 months. RESULTS: A total of 952 smoker fathers and mothers were randomized to the intervention (n = 467) and control (n = 485) groups. Most were daily smokers (92.4%) and the mean number of cigarettes smoked per day was 14.5 (SD = 8.9). By using intention-to-treat analysis, the 7 day point prevalence quit rate at 6 month follow up was significantly greater in the intervention group (15.3%; 68/444) than the control group (7.4%; 34/459) (P < 0.001). The absolute risk reduction was 7.9% (95% confidence interval: 3.78% to 12.01%). The number needed to treat to get one additional smoker to quit was 13 (95% CI: 8-26). The crude odds ratio of quitting was 2.3(95% CI: 1.5-3.5). The adjusted odds ratio was 2.1 (95% CI: 1.4-3.4) (adjusted for age, number of years smoked, and alcohol dependency). CONCLUSION: Proactive telephone counselling is an effective aid to promote smoking cessation among parents of young children.     

A randomized controlled trial of stage-matched intervention for smoking cessation in cardiac out-patients

Aim To examine the effectiveness of a stage‐matched smoking cessation counselling intervention for smokers who had cardiac diseases. Methods A total of 1860 Chinese cardiac patients who smoked at least one cigarette in the past 7 days and aged 18 years or above recruited from cardiac out‐patient clinics in Hong Kong hospitals were allocated randomly to an intervention group or control group. The intervention group (n = 938) received counselling matched with their stage of readiness to quit by trained counsellors at baseline, 1 week and 1 month. The control group (n = 922) received brief counselling on healthy diet at baseline. The primary outcomes were self‐reported 7‐day and 30‐day point prevalence (PP) of tobacco abstinence at 12 months after baseline. The secondary outcome measures included biochemically validated abstinence at 12‐month follow‐up, self‐reported 7‐day and 30‐day PP abstinence and reduction of cigarette consumption by 50% at 3 and 6 months. Results By intention‐to‐treat analysis, the intervention and control groups showed no significant difference in self‐reported 7‐day PP abstinence (intervention: 26.5% versus control: 25.5%; P = 0.60) and 30‐day PP (intervention: 25.4% versus control: 24.2%; P = 0.55), biochemically validated abstinence (intervention: 6.6% versus control: 4.9%; P = 0.14) and overall quit attempts of least 24 hours (intervention: 40.3% versus control: 34.3%; P = 0.007) at the 12‐month follow‐up, adjusted for the baseline stage of readiness to quit smoking. Conclusions An intervention, based on the Stages of Change model, to promote smoking cessation in cardiac patients in China failed to find any long‐term benefit.     

A multi‐level analysis of non‐significant counseling effects in a randomized smoking cessation trial

Aims To determine, in the context of a trial in which counseling did not improve smoking cessation outcomes, whether this was due to a failure of the conceptual theory identifying treatment targets or the action theory specifying interventions. Design Data from a randomized clinical trial of smoking cessation counseling and bupropion SR were submitted to multi‐level modeling to test whether counseling influenced real‐time reports of cognitions, emotions and behaviors, and whether these targets predicted abstinence. Setting Center for Tobacco Research and Intervention, Madison, WI. Participants A total of 403 adult, daily smokers without contraindications to bupropion SR use. Participants were assigned randomly to receive individual counseling or no counseling and a 9‐week course of bupropion SR or placebo pill. Cessation counseling was delivered in eight 10‐minute sessions focused on bolstering social support, motivation, problem‐solving and coping skills. Measurements Pre‐ and post‐quit ecological momentary assessments of smoking behavior, smoking triggers, active prevention and coping strategies, motivation to quit, difficulty quitting and reactions to initial lapses. Findings Counseling prompted avoidance of access to cigarettes, improved quitting self‐efficacy, reduced perceived difficulty of quitting over time and protected against guilt and demoralization following lapses. Results also supported the importance of limiting cigarette access, receiving social support, strong motivation and confidence and easing withdrawal distress during cessation efforts. Quitting self‐efficacy and perceived difficulty quitting may partially mediate counseling effects on abstinence. Conclusions Smoking cessation counseling may work by supporting confidence about quitting and reducing perceived difficulty quitting. Counseling did not affect other targets that protect against relapse.     

The safety,effectiveness and cost‐effectiveness of cytisine in achieving six‐month continuous smoking abstinence in tuberculosis patients—protocol for a double‐blind,placebo‐controlled randomized trial

Background and aims

Tuberculosis (TB) patients who quit smoking have much better disease outcomes than those who continue to smoke. In general populations, behavioural support combined with pharmacotherapy is the most effective strategy in helping people to quit. However, there is no evidence for the effectiveness of this strategy in TB patients who smoke. We will assess the safety, effectiveness and cost‐effectiveness of cytisine—a low‐cost plant‐derived nicotine substitute—for smoking cessation in TB patients compared with placebo, over and above brief behavioural support.

Design

Two‐arm, parallel, double‐blind, placebo‐controlled, multi‐centre (30 sites in Bangladesh and Pakistan), individually randomized trial.

Setting

TB treatment centres integrated into public health care systems in Bangladesh and Pakistan.

Participants

Newly diagnosed (in the last 4 weeks) adult pulmonary TB patients who are daily smokers (with or without dual smokeless tobacco use) and are interested in quitting (n = 2388).

Measurements

The primary outcome measure is biochemically verified continuous abstinence from smoking at 6 months post‐randomization, assessed using Russell Standard criteria. The secondary outcome measures include continuous abstinence at 12 months, lapses and relapses; clinical TB outcomes; nicotine dependency and withdrawal; and adverse events.

Comments

This is the first smoking cessation trial of cytisine in low‐ and middle‐income countries evaluating both cessation and TB outcomes. If found effective, cytisine could become the most affordable cessation intervention to help TB patients who smoke.