The Design and Multi-Method Evaluation of a Pilot Pragmatic Randomised Controlled Trial of an Exercise Assisted Reduction of Smoking Intervention among Socioeconomically Disadvantaged Smokers
Thompson, Thomas Paul
Thesis or dissertation
University of Exeter
Background: Smoking contributes to health inequalities and there is a need to focus interventions on the disadvantaged. Abrupt quitting is widely advocated, but assisted ‘reduction’ may be an option for those not ready to quit. Physical activity acutely reduces cigarette cravings and withdrawal symptoms, and may increase long-term cessation and reduce weight gain. This thesis reports on the multi-method evaluation of an intervention delivered by Health Trainers (HTs) and a pilot randomised controlled trial of the Exercise Assisted Reduction then Stop (EARS) intervention for disadvantaged smokers who are not ready to quit, but do wish to reduce, without nicotine replacement therapy. This programme of research aimed to evaluate four aspects of the EARS trial: 1) Recruitment, 2) Study attrition, 3) Main quantitative outcomes, and 4) Intervention fidelity. Methods: 1) Recruitment: Smokers were recruited through mailed invitations from three primary care practices (62 participants) and one National Health Stop Smoking Service (SSS) database (31 participants). Six other participants were recruited via a variety of other community-based approaches. Data were collected through questionnaires, field notes, work sampling, and databases. Chi-squared and t-tests were used to compare baseline characteristics of participants. 2) Study Attrition: Disadvantaged smokers who wanted to reduce but not quit were randomised (N=99), of whom 61 (62%) completed follow-up assessments at 16 weeks. Univariable logistic regression was conducted to determine the effects of intervention arm, method of recruitment, and participant characteristics (socio-demographic factors, and lifestyle, behavioural and attitudinal characteristics) on attrition, followed by multivariable logistic regression on those factors found to be related to attrition. 3) Main quantitative outcomes: Data at 16 weeks were collected for various smoking and physical activity outcomes. Primary analyses consisted of an intention to treat analysis based on complete case data. Secondary analyses explored the impact of handling missing data, examining different methods including last baseline observation carried forward, last observation carried forward, and multiple imputation. 4) Intervention fidelity: Three researchers scored a total of 90 audio recorded consultations for 30 different participants split between three HTs delivering the intervention. Delivery was scored using a 0-6 likert scale for 12 different processes identified as being fundamental to the intervention. Results: 1) Recruitment: Depending on the intensity and time invested in following up those who did not initially respond to a letter, we randomised between 5.1–11.1% of those invited through primary care and SSS, with associated researcher time to recruit one participant varying from 18 –157 minutes. Recruitment rates were similar for invitations sent from primary care and SSS. Despite substantial time and effort, only six participants of our total of 99 were recruited through a wide variety of other community-based approaches, with an associated researcher time of 469 minutes to recruit one participant. Targets for recruiting a disadvantaged population were met, with 91% of the sample in social classes C2–E, and 41% reporting moderate to severe depression or anxiety. However, we under-recruited single parent smokers. Chi squared tests revealed that those recruited from the SSS database were more likely to respond to an initial letter, had used cessation aids before and had attempted to quit in the past year. Overall, initial responders were more likely to be physically active than those who were recruited via follow-up telephone calls. No other demographic or behaviour characteristics were associated with recruitment approach or intensity of effort. Qualitative feedback indicated that participants had been attracted by the prospect of being assigned to an intervention that focused on smoking reduction rather than abrupt quitting. 2) Attrition: Participants with low confidence to quit, and who were undertaking less than 150 minutes of moderate and vigorous physical activity per week at baseline were less likely to complete the 16-week follow-up assessment. Exploratory analysis revealed that those who were lost to follow-up early in the trial (i.e., by 4 weeks), compared with those completing the study, were younger, had smoked for fewer years and had lower confidence to quit in the next 6 months. Participants who recorded a higher expired air carbon monoxide reading at baseline were more likely to drop out late in the study, as were those recruited via follow-up telephone calls. Multivariable analyses showed that only completing less than 150 minutes of physical activity retained any confidence in predicting attrition in the presence of other variables. 3) Main quantitative outcomes: Compared with controls, intervention smokers made more quit attempts (36 v 10%; Odds Ratio 5.05, (95% CI: 1.10; 23.15)), and a greater proportion achieved ≥ 50% reduction in cigarettes smoked (63 v 32%; 4.21 (1.32; 13.39). Post-quit abstinence measured by exhaled carbon monoxide at 4 week follow-up showed promising differences between groups (23% v 6%; 4.91 (0.80; 30.24). No benefit of intervention on physical activity was found. Secondary analyses suggested that the standard missing data assumption of ‘missing’ being equivalent to ‘smoking’ may be conservative resulting in a reduced intervention effect. 4) Fidelity: All three HTs demonstrated high levels of skill in delivering a client-centred motivational interviewing based intervention. Processes relating to physical activity were not delivered as well as those relating to smoking behaviour. Processes related to social support were poorly delivered. There was little variation between individual HT scores and the scores of the researchers completing the scoring. Conclusions: 1) Recruitment: Mailed invitations, and follow-up, from health professionals was an effective method of recruiting disadvantaged smokers into a trial of an exercise intervention to aid smoking reduction. Recruitment via community outreach approaches was largely ineffective. 2) Study attrition: The findings indicate that those who take more effort to be recruited, are younger, are heavier smokers, have less confidence to quit, and are less physically active require more effort to be retained once recruited . 3) Main quantitative outcomes: A smoking reduction intervention for economically disadvantaged smokers which involved personal support to increase physical activity appears to be more effective than usual care in achieving reduction and may promote cessation. The effect does not appear to be influenced by an increase in physical activity. 4) Intervention fidelity was deemed to be successful overall. Key areas for improvement have been identified, including recommendations for future training as well as methodological implementation.
PhD in Sport and Health Sciences