Predictors of Adherence to Nicotine Replacement Therapy (Nicotine Patch) Among Homeless Persons Enrolled in a Randomized Controlled Trial Targeting Smoking Cessation

Special Article – Tobacco and Smoking Cessation

J Fam Med. 2016; 3(7): 1079.

Predictors of Adherence to Nicotine Replacement Therapy (Nicotine Patch) Among Homeless Persons Enrolled in a Randomized Controlled Trial Targeting Smoking Cessation

Ojo-Fati O1,2*, Thomas JL2,3,4, Vogel RI4,5, Ogedegbe O6, Jean-Louis G6 and Okuyemi KS1,2,4

1Department of Family Medicine and Community Health, University of Minnesota, Minneapolis, MN, USA

2Program in Health Disparities Research, University Of Minnesota, Minneapolis, MN, USA

3Department of Medicine, University of Minnesota, Minneapolis, MN, USA

4Masonic Cancer Center, University of Minnesota, Minneapolis, MN, USA

5Department of Obstetrics, Gynecology and Women’s Health, University of Minnesota, Minneapolis, MN, USA

6Department of Population Health, New York University School of Medicine, New York, NY, USA

*Corresponding author: Ojo-Fati O, Program in Health Disparities Research, University of Minnesota Medical School, 717 Delaware Street SE, Suite 166, Minneapolis, MN 55414, USA

Received: August 12, 2016; Accepted: September 02, 2016; Published: September 06, 2016


Introduction: Adherence to smoking cessation treatment is generally low, especially among socio-economically disadvantaged groups including individuals experiencing homelessness and those with mental illnesses. Despite the high smoking rates in homeless populations (~70%) no study to date has systematically examined predictors of adherence to nicotine replacement therapy (NRT) in this population.

Objective: The aim of this secondary analysis was to identify predictors of adherence to NRT in a smoking cessation trial conducted among homeless smokers.

Methods: Secondary analysis of data from a randomized controlled trial enrolling 430 persons who were homeless and current cigarette smokers. Participants were assigned to one of the two study conditions to enhance smoking cessation: Motivational Interviewing (MI; 6 sessions of MI + 8 weeks of NRT) or Standard Care (Brief advice to quit+ 8 weeks of NRT). The primary outcome for the current analysis was adherence to NRT at end of treatment (8 weeks following randomization). Adherence was defined as a total score of zero on a modified Morisky adherence scale). Demographic and baseline psychosocial, tobacco-related, and substance abuse measures were compared between those who did and did not adhere to NRT.

Results: After adjusting for confounders, smokers who were depressed at baseline (OR=0.58, 95% CI, 0.38-0.87, p=0.01), had lower confidence to quit (OR=1.10, 95% CI, 1.01-1.19, p=0.04), were less motivated to adhere (OR=1.04, 95% CI, 1.00-1.07, p=0.04), and were less likely to be adherent to NRT. Further, age of initial smoking was positively associated with adherence status (OR= 0.83, 95% CI, 0.69-0.99, p=0.04).

Conclusion: These results suggest that smoking cessation programs conducted in this population may target increased adherence to NRT by addressing both depression and motivation to quit.

Trial Registration: NCT00786149.

Keywords: Smoking cessation; Adherence; Homeless populations; Nicotine replacement therapy; Patch; Randomized controlled trials


Tobacco use remains the most common preventable cause of death in the United States with more than 480,000 deaths reported annually [1]. The impact of tobacco use on health in the general population is overwhelming. In addition, secondhand smoke is associated with almost 50,000 deaths per year in the United Sates alone [2]. Efforts made to reduce the prevalence of tobacco use and the exposure to environmental tobacco smoke has contributed to a 50% decline in smoking rates in the past 25 years. However, smoking prevalence remains high among several socio-economically disadvantaged groups including the homeless (~70%) and patients with mental illnesses [3-6]. Tobacco related illnesses such as lung and esophageal cancer, coronary heart disease, and respiratory diseases are the primary causes of death among persons who are homeless [1,7-9].

One factor that has been shown to directly affect the success of smoking cessation treatment is adherence to pharmacotherapy, which might be an especially salient issue for homeless persons [10,11]. NRT use has been shown to increase cessation rates by 60% [12-14] and has been found to be effective even without behavioral treatment [10,15-17]. Despite proven efficacy, adherence to NRT has been poor in clinical trials especially among socioeconomically- disadvantaged groups [4,11,18,19]. Adherence to smoking cessation treatments in the homeless population could be significantly affected by several variables unique to this community including high levels of high prevalence of illicit drug use, HIV/AIDS, and mental illness, stress, and competing needs [20,21]. In studies in non-homeless populations, some baseline variables have been found to influence adherence to therapy. A recent review examined the effectiveness of interventions to improve adherence to medications for nicotine dependence [22]. The review found that adherence interventions led to marginal improvements in adherence, with a relative risk (RR) of 1.14 (95% CI, 1.02 to 1.28, P = 0.02, n = 1630). In addition to the multiple barriers that homeless smokers face, studies have shown that psychological factors including depression, stress, and generalized anxiety disorder that might impact smoking cessation are also highly prevalent in homeless populations [23-25]. Thus, adherence to smoking cessation treatment under these circumstances can be challenging. Unfortunately, little is known about effective cessation interventions among homeless populations. Low rates of medication adherence among the homeless suggest that adherence to NRT might be low and merit special attention in any pharmacotherapy trials. To date there are no controlled trials of interventions to improve adherence to self-administered medications, such as nicotine replacement therapy, that specifically target homeless persons. Even in the general population, adherence to treatment has limited NRT’s effectiveness especially in real-world settings [19]. Considering the presence of numerous barriers to medication adherence in homeless populations, problems with adherence to NRT is likely to be of a greater magnitude in homeless populations. This study broadly addresses these gaps in the literature.

To the best of our knowledge no published studies have identified the predictors of adherence to NRT in homeless populations. Most medication adherence studies among homeless persons focus on HIV and tuberculosis medication treatment. Studies indicate that even when these medications are provided free of charge, adherence rates can be low [26].

The purpose of this study was to conduct a secondary analysis to identify the predictors of adherence to smoking cessation treatment among 430 smokers who are homeless participated in a communitybased smoking cessation trial. The randomized controlled trial [RCT] known as Power To Quit (PTQ) was the first published smoking cessation RCT in a homeless population [19,27]. Increased understanding of factors associated with adherence to nicotine patch in smokers who are homeless has a high potential to inform effective smoking cessation interventions for this population.


Study design

The PTQ study was approved and monitored by the University of Minnesota’s Institutional Review Board. Study methodology, design and primary outcomes of the trial have been fully described elsewhere [4,27]. The PTQ study was a two-arm randomized controlled trial [RCT] of 430 homeless adult smokers that compared Standard Care (one-time brief advice to quit smoking) with six Motivational Interviewing (MI) sessions. All participants received nicotine patches (21mg) for eight weeks.

Participant eligibility and recruitment

Detailed eligibility criteria have been discussed and published elsewhere [19]. In summary, inclusion criteria included being currently homeless [2], smoked at least 5 cigarettes per day, smoked at least 100 cigarettes in lifetime, and smoked at least one cigarette every day over the past 7 days, aged 18 years or older, willing to use a nicotine patch for 8 weeks and participate in counseling sessions, and willing to complete 15 total appointments (6 during NRT treatment, 8 retention contacts, and a final exit interview survey) over a 26-week study period. Informed consent was obtained from each participant before the initiation of any study procedures. Additional eligibility criteria included living in the mid-west region of the United States for at least 6 months and planning to stay in the area for the next 6 months; and for women, not currently pregnant and willing to use birth control. Participants were deemed ineligible for the study if they had cognitive impairment, suicidal ideation in the last 14 days, a major medical condition (heart attack or stroke) within the prior month, or scored greater than 5 on items assessing psychotic symptoms from the Mini International Neuropsychiatric Interview (M.I.N.I.) [28] or used another tobacco cessation aid (e.g., patch, gum) in the previous 30 days.

Intervention components

Intervention components of the study have been described in detail elsewhere [27] and are summarized briefly below.

Nicotine patch

The patch was chosen as the NRT to use for this study among homeless smokers because of its cost-effectiveness, availability, easy dosing and efficacy [29,30]. The patch has been proven to be safe and effective for smoking cessation [16,17,30]. Further information gathered during the pilot clinical trial that informed the final design of this RCT found that 70% of participants chose the patch and 30% chose the lozenge when both were offered. All participants received 21mg nicotine patches along with use instructions at baseline. Study staff distributed a two-week supply of 21-mg nicotine patches to participants in both groups at randomization and each follow-up visit.

Motivational interviewing

Motivational Interviewing (MI) is designed to enhance motivation for behavior change [31]. Participants randomized to the intervention arm were offered six 20-minute MI counseling sessions from trained counselors. MI counseling sessions occurred at baseline and weeks 1,2,4,6, and 8. The target behavior for the MI sessions was NRT adherence and smoking cessation.

At the initiation of the project, MI counselors received two full days of training on the theory and method of conducting MI counseling sessions followed by approximately 40 hours of supervised training by a licensed clinical psychologist trained in MI. Ongoing fidelity monitoring was conducted by weekly group meetings in which audio taped sessions were reviewed and corrective feedback provided. Approximately 10% of each counselor’s weekly sessions were reviewed using the motivational interviewing treatment integrity (MITI) code 3.0 scoring criteria [32].

Standard care

Participants in the Standard Care control condition received one-session of brief advice to quit smoking. This session was based on the US Public Health Service’s Guidelines [33] and was delivered by trained study counselors who did not provide MI counseling. During the 10-15 minute standard care session counselors assessed participant smoking history, current smoking and readiness to quit; provided direct advice about the health risks of smoking and the health benefits of quitting and strategies for coping with urges, and affirmed the participant’s decision to quit.

Outcomes and measurements

Adherence: This study attempted to address the challenge of using self-reported data on patch adherence by using an innovation shown to address shortcomings adapted from the literature on ART adherence [34]. Adherence was defined as a total score of zero in a modified Morisky adherence scale at end of NRT treatment (8 weeks) [35]. The Morisky scale is comprised of 4 items with a scoring system of “Yes” = 1 and “No” = 0. The four items are; 1) Did you ever forget to use your nicotine patch? 2) Are you careless at times about using your nicotine patch? 3) When you feel better, do you sometimes stop using your nicotine patch? and 4) Sometimes if you feel worse when you use your nicotine patch, do you stop using it? The items were summed to give a range of scores from 0 to 4. Participants scoring >0 were classified as non-adherent. All data collected on the survey forms was entered directly into RED Cap (Research Electronic Data Capture; https:// project-redcap. org/ ). The project manager monitored quality control and endeavored to "clean" the data after completing the study visits/data entry.

Measures: Demographic variables collected as part of the study included age, gender, race/ethnicity, monthly family income, education level, and history of homelessness including number of times homeless and duration of homelessness. Participants were asked when they started smoking regularly, how many cigarettes they smoked per day, time to first cigarette, if they smoked menthol cigarettes, number of 24 hour quit attempts in the past year, motivation to quit and confidence to quit. Psychosocial variables assessed included the patient health questionnaire (PHQ-9) for depression [36], the 4-item perceived stress scale for stress in past 30 days [37], the M.I.N.I. for screening psychosis or cognitive impairment and generalized anxiety disorder assessment [28]. Participants were also asked about drug and alcohol use dependence. The Motivation/Confidence to adhere scale [38], a 5-item scale with a score range of 1-10 for each item reflecting readiness and commitment to adhere to smoking cessation was used to assess motivation and confidence to adhere to NRT patch; Self- Efficacy to adhere [39] measure, a modified 10-item adapted from the Adult AIDS Clinical Trials Group (AACTG) were used to rate selfefficacy to adhere to treatment [40].

Statistical analysis

Demographic, psychosocial, tobacco-related, and substance abuse measures were compared between those who did and did not adhere to NRT using Chi-squared and Fisher Exact tests as appropriate for categorical variables and t-tests assuming unequal variances for continuous variables. A multivariate logistic regression analysis was conducted including randomization group in the model along with variables identified in the univariate analyses (p=0.10), including age they started regular smoking, whether they smoked menthol cigarettes, and baseline depression, stress, confidence to quit and motivation to adhere. All statistical analyses were performed using SAS 9.3 (SAS Institute, Cary, NC) and p-values of <0.05 were considered statistically significant.


As detailed in Table 1, the study sample consisted of 430 persons who were homeless and current cigarette smokers. Participants had a mean age of 44. 4 ± 9.9 years, were African American (56.3%), male (74.7%), unemployed (90.5%), and completed at least high school education or equivalent (76.7%). When looking at factors associated with adherence separately, those who were depressed (p=0.0002), had lower confidence in their ability to quit smoking (p=0.05) or who were less motivated to adhere to treatment at baseline (p=0.05) were less likely to adhere to NRT.

Citation:Ojo-Fati O, Thomas JL, Vogel RI, Ogedegbe O, Jean-Louis G and Okuyemi KS. Predictors of Adherence to Nicotine Replacement Therapy (Nicotine Patch) Among Homeless Persons Enrolled in a Randomized Controlled Trial Targeting Smoking Cessation. J Fam Med. 2016; 3(7): 1079. ISSN : 2380-0658