A tutorial on principal stratification-based sensitivity analysis: application to smoking cessation studies.

BACKGROUND: One problem with assessing effects of smoking cessation interventions on withdrawal symptoms is that symptoms are affected by whether participants abstain from smoking during trials. Those who enter a randomized trial but do not change smoking behavior might not experience withdrawal-related symptoms. PURPOSE: We present a tutorial of how one can use a principal stratification sensitivity analysis to account for abstinence in the estimation of smoking cessation intervention effects. The article is intended to introduce researchers to principal stratification and describe how they might implement the methods. METHODS: We provide a hypothetical example that demonstrates why estimating effects within observed abstention groups is problematic. We demonstrate how estimation of effects within groups defined by potential abstention that an individual would have in either arm of a study can provide meaningful inferences. We describe a sensitivity analysis method to estimate such effects, and use it to investigate effects of a combined behavioral and nicotine replacement therapy intervention on withdrawal symptoms in a female prisoner population. RESULTS: Overall, the intervention was found to reduce withdrawal symptoms but the effect was not statistically significant in the group that was observed to abstain. More importantly, the intervention was found to be highly effective in the group that would abstain regardless of intervention assignment. The effectiveness of the intervention in other potential abstinence strata depends on the sensitivity analysis assumptions. LIMITATIONS: We make assumptions to narrow the range of our sensitivity analysis estimates. While appropriate in this situation, such assumptions might not be plausible in all situations. CONCLUSIONS: A principal stratification sensitivity analysis provides a meaningful method of accounting for abstinence effects in the evaluation of smoking cessation interventions on withdrawal symptoms. Smoking researchers have previously recommended analyses in subgroups defined by observed abstention status in the evaluation of smoking cessation interventions. We believe that principal stratification analyses should replace such analyses as the preferred means of accounting for post-randomization abstinence effects in the evaluation of smoking cessation programs. Clinical Trials 2010; 7: 286-298. http://ctj.sagepub.com.

The impact of email recruitment on our understanding of college smoking.

Email recruitment is growing in popularity; however, this convenience sampling method may yield very different results from prior convenience sampling methods. Participants in the current study were 825 undergraduate students, 446 recruited through a campus wide email and 379 recruited through Introductory Psychology courses, who completed an on-line survey on smoking and health. Outcomes varied significantly by group. Introductory Psychology students reported higher smoker self-concept, more pros of smoking, and were more likely to view smoking as a method of negative affect reduction. The current study suggests that recruitment method can bias our understanding of smoking behaviors among college students.

A randomized trial of a proactive cellular telephone intervention for smokers living with HIV/AIDS.

OBJECTIVE: To assess the efficacy of an innovative smoking cessation intervention targeted to a multiethnic, economically disadvantaged HIV-positive population. DESIGN: A two-group randomized clinical trial compared a smoking cessation intervention delivered by cellular telephone with usual care approach. METHODS: Current smokers from a large, inner city HIV/AIDS care center were recruited and randomized to receive either usual care or a cellular telephone intervention. The usual care group received brief physician advice to quit smoking, targeted self-help written materials and nicotine replacement therapy. The cellular telephone intervention received eight counseling sessions delivered via cellular telephone in addition to the usual care components. Smoking-related outcomes were assessed at a 3-month follow-up. RESULTS: The trial had 95 participants and 77 (81.0%) completed the 3-month follow-up assessment. Analyses indicated biochemically verified point prevalence smoking abstinence rates of 10.3% for the usual care group and 36.8% for the cellular telephone group; participants who received the cellular telephone intervention were 3.6 times (95% confidence interval, 1.3-9.9) more likely to quit smoking compared with participants who received usual care (P = 0.0059). CONCLUSIONS: These results suggest that individuals living with HIV/AIDS are receptive to, and can be helped by, smoking cessation treatment. In addition, smoking cessation treatment tailored to the special needs of individuals living with HIV/AIDS, such as counseling delivered by cellular telephone, can significantly increase smoking abstinence rates over that achieved by usual care.

Successes and failures of the teachable moment: smoking cessation in cancer patients.

BACKGROUND: Successful cancer treatment can be significantly compromised by continued tobacco use. Because motivation and interest in smoking cessation increase after cancer diagnosis, a window of opportunity exists during which healthcare providers can intervene and assist in the quitting process. METHODS: The authors conducted a comprehensive literature review to discuss 1) the benefits of smoking cessation in cancer patients, 2) current knowledge regarding smoking cessation interventions targeted to cancer patients, and 3) treatment models and state-of the-art guidelines for intervention with cancer patients who smoke. The authors present clinical cases to illustrate the challenging nature of smoking cessation treatment for cancer patients. RESULTS: Continued smoking after cancer diagnosis has substantial adverse effects on treatment effectiveness, overall survival, risk of second primary malignancies, and quality of life. Although some encouraging results have been demonstrated with smoking cessation interventions targeted to cancer patients, few empirical studies of such interventions have been conducted. A range of intervention components and state-of-the-art cessation guidelines are available that can be readily applied to cancer patients. Case illustrations highlight the crucial role of healthcare providers in promoting smoking cessation, the harmful impact of nicotine addiction manifested in delayed and failed reconstructive procedures, and unique problems encountered in treating patients who have particular difficulty quitting. CONCLUSIONS: Despite the importance of stopping smoking for all cancer patients, the diagnosis of cancer is underused as a teachable moment for smoking cessation. More research is needed to empirically test cessation interventions for cancer patients, and attention must be given to complex and unique issues when tailoring cessation treatment to these individuals.

Using metadata to generate web-based Electronic Data Capture Forms.

Generation of web-based Electronic Data Capture Forms (EDCF) from XML-encoded metadata is an efficient and reliable way to support research data collection. Using metadata-driven development we improved efficiency, maximized reuse and consistency. We describe why we developed our EDCF generator in this manner, our design goals and highlight two representative studies that made use of this approach.

Smoking behavior in a low-income multiethnic HIV/AIDS population.

The aim of this study was to describe smoking prevalence and smoking behavior in a multiethnic low-income HIV/AIDS population. A cross-sectional survey design was used. The study site was Thomas Street Clinic, an HIV/AIDS care facility serving a medically indigent and ethnically diverse population. Demographic, disease status, behavioral, and psychosocial variables were assessed by participant self-report. Surveys were collected from 348 study participants. Demographic composition of the sample was 78% male, 25% White, 44% Black, and 29% Hispanic. Study participants had a mean age of 40.2 years (SD=7.8). The HIV exposure profile of the sample was diverse: 46% men who have sex with men, 35% heterosexual contact, and 11% injection drug use. Prevalence of current cigarette smoking in the sample was 46.9%. Among participants with a lifetime history of smoking 100 or more cigarettes (62.8%), only 26.6% were currently abstinent, lower than the 48.8% rate seen in the general population. Multiple logistic regression analysis indicated that race/ethnicity, education level, age, and heavy drinking were significantly associated with smoking status. Hispanics were less likely than Whites were to smoke, younger participants were less likely than older participants were to be current smokers, and heavy drinkers were more likely to be current smokers than were those who were not heavy drinkers. As education level increased, the likelihood of smoking decreased and the likelihood of quitting increased. The high smoking prevalence in this HIV/AIDS population demonstrates the need for smoking cessation interventions targeted to the special needs of this patient group.

Pretreatment task persistence predicts smoking cessation outcome.

R. Eisenberger's (1992) learned industriousness theory states that individuals display differing degrees of persistence depending on their history of reinforcement for effortful behavior. These differences may influence the development, maintenance, and cessation of addictive behaviors. In cross-sectional studies, E. P. Quinn, T. H. Brandon, and A. L. Copeland (1996) found that cigarette smokers were less persistent than nonsmokers, and R. A. Brown, C. W. Lejuez, C. W. Kahler, and D. R. Strong (2002) found that smokers who had previously abstained for 3 months were more persistent than those who had never quit. The present study extended these findings by using a prospective design. A pretreatment measure of task persistence (mirror tracing) completed by 144 smokers predicted sustained abstinence throughout 12 months of follow-up. Moreover, persistence predicted outcome independent of other significant predictors: gender, nicotine dependence, negative affect, and self-efficacy.