Can a smartphone application help Hispanic/Latinx adults quit smoking? A randomized trial secondary analysis

Abstract

Introduction:

There are no known efficacious digital smoking cessation interventions for Hispanic/Latinx adults who smoke. This study is a secondary analysis using data from a randomized trial to evaluate whether Acceptance and Commitment Therapy (ACT) delivered via a smartphone app (iCanQuit) would be more efficacious for smoking cessation than the US Clinical Practice (USCPG)-based app (QuitGuide) in a sample of Hispanic/Latinx participants.

Methods:

A total of 210 Hispanic/Latinx adults who smoke were randomized to receive the iCanQuit or QuitGuide app for 12-months. Participants self-reported on 30-day abstinence from cigarette smoking at the 3-month, 6-month, and 12-month follow-ups; 7-day abstinence at all follow-ups; abstinence from other nicotine/tobacco products at 12-months; and continuous prolonged abstinence from 3 to 12-months. Participants also reported on their willingness to accept cues to smoke without smoking and satisfaction with their apps.

Results:

A total of 176 (84%) participants reported on study outcomes at the 12-month follow-up. Compared to QuitGuide participants, iCanQuit participants were significantly more likely to report 30-day abstinence from cigarette smoking at 12-months (34% iCanQuit, 20% QuitGuide; p=0.026). iCanQuit participants utilized their app more frequently and reported greater satisfaction with their assigned app than those who received the QuitGuide app. Increases in participants’ willingness to accept cues to smoke mediated the intervention effect on abstinence from cigarette smoking at 12-months.

Conclusions:

Acceptance and Commitment Therapy-delivered via a smartphone app may be efficacious for helping Hispanic/Latinx adults abstain from cigarette smoking. Replication in a fully powered randomized trial that focuses on an independent sample of Hispanic/Latinx adults is now needed.

1. Introduction

Although the prevalence of cigarette smoking in the United States (US) is at an all-time low,^1,2 the burden of smoking-attributable morbidity and mortality falls disproportionally among racial and ethnic minorities, including the Hispanic or Latino population^3–5 (referred to hereafter as Hispanic/Latinx to describe people of any gender who have a background in a Spanish-speaking country or Latin American country).^6,7 Cigarette smoking contributes to the leading causes of death among the Hispanic/Latinx population, including heart disease, cancer, and stroke.^8,9 Despite making more quitting attempts, Hispanic/Latinx adults are the least likely to successfully quit smoking when compared to their non-Hispanic/Latinx counterparts.¹⁰ Further, Hispanic/Latinx adults who smoke face unique challenges to receiving evidence-based smoking cessation treatment,^11,12 including being the least likely of any other racial/ethnic group to have access to health care,^13,14 which further contributes to their low smoking cessation rates and higher smoking-attributable morbidity and mortality, making them a high priority population.

Given this priority, there is now a need for innovative research that focuses on helping Hispanic/Latinx adults quit smoking to help alleviate the tremendous burden attributable to cigarette smoking among US racial/ethnic minority groups who are underrepresented in smoking cessation trials.^15,16 Although there are efficacious treatments for helping the general population of adult smokers quit,^17,18 Hispanic/Latinx adults are rarely offered these interventions.² Moreover, Hispanic/Latinx adults have the lowest rate of health insurance coverage in the US, which poses an immediate barrier to receiving treatment.^13,16,19,20 Underrepresentation of Hispanic/Latinx adults in smoking cessation trials, in conjunction with low rates of health insurance coverage, may contribute to the low rates of treatment utilization among Hispanic/Latinx adults.²¹ In fact, Hispanic/Latinx adults are less likely to use counseling and/or medication for smoking cessation when compared with their non-Hispanic White counterparts (19.2% vs. 34.3%).²¹ Additional barriers to access to treatment include experienced discrimination^22,23 and resulting mistrust of the medical system.^24,25 Overcoming the inequities in accessibility barriers to treatments is important to enable Hispanic/Latinx adults who smoke to engage with evidence-based smoking cessation programs and sustain behavior changes.

Considering that the Hispanic/Latinx population comprise 19% of the US population and is expected to double in size by 2060,^26,27 there is limited evidence on existing smoking cessation programs that are both engaging and efficacious in this population.^22,28 Simmons et al.²⁹ conducted a randomized controlled trial (RCT) among 1417 Hispanics/Latinx adults who smoke. That study consisted of a culturally tailored smoking cessation intervention of mailed written materials over a period of 18 months versus a one-time booklet developed by the National Cancer Institute (NCI). The 24-month quit rates in the intervention were 33.1% versus 24.3% in the control group. However, the results are limited by a high percentage of missing data (47% at 24 months), which suggests considerable disengagement with the intervention overtime.

One potential strategy to further increase accessibility to evidence-based smoking cessation programs, and thereby improve treatment utilization and cessation outcomes, is the use of digital interventions that are remotely delivered and freely available. For example, smartphone applications (“apps”) have potentially high population-level reach to the Hispanic/Latinx population considering 85% of Hispanic/Latinx adults in the US own smartphones.³⁰ Therefore, smartphone apps for smoking cessation may help improve accessibility to treatments because they are low cost, scalable, and can support people anywhere and anytime. Accessibility is particularly increased for smartphone apps that can be downloaded on users’ phones and require no broadband access to use. Yet, there is no prior evidence from RCTs on the efficacy of app-delivered smoking cessation interventions for the Hispanic/Latinx population.^31–35

Accumulating evidence shows that Acceptance and Commitment Therapy (ACT)-based app-delivered smoking cessation interventions improve abstinence from cigarette smoking in the general population (citations removed for anonymized review). The iCanQuit smartphone app for smoking cessation is based on ACT and was tested in a two-arm RCT against the US Clinical Practice Guidelines (USCPG)-based NCI’s smartphone app (QuitGuide) in 2415 adults who smoke. At 12-months, 28% of participants who received iCanQuit reported 30-day abstinence from cigarette smoking compared to 21% of participants who received QuitGuide (citation removed for anonymized review). Specific to smoking cessation, the goal of ACT-based strategies is to cultivate a willingness to tolerate potentially aversive experiences while simultaneously promoting smoke-free days consistent with desired goals and values.^36–40 These psychological components distinguish ACT from standard treatments such as USCPG that focus on avoidance of urges to smoke and motivate by using logic.⁴¹ Further, unwillingness to tolerate aversive experiences and physical sensations have been linked to poorer behavioral health, poorer quit success, and greater perceived barriers for quitting among Hispanic/Latinx adults.^42–50

The present article reports on a secondary analysis of data from the iCanQuit parent RCT to (1) explore the efficacy of iCanQuit relative to QuitGuide for smoking cessation among English-speaking Hispanic/Latinx adult daily smoking participants (as per the main trial eligibility criteria); (2) compare utilization of the apps and satisfaction across arms, and (3) evaluate whether increases in the willingness to experience cues to smoke (e.g., acceptances of cues to smoke) without smoking mediated the effect of the intervention on reported abstinence from cigarette smoking.

2. Methods

2.1. Overview

Data for this secondary analysis were from adults (≥18 years) who self-reported Hispanic or Latino ethnic backgrounds (n=210; 8.7% of the total sample) enrolled in the two-arm randomized iCanQuit parent trial (citation removed for anonymized review). The iCanQuit parent RCT enrolled a racially/ethnically diverse sample of 2415 adults who smoke daily from all 50 US states to participate in a 12-month app-delivered smoking cessation intervention. The primary aim of the trial was to test the efficacy of the ACT-based iCanQuit app against the USCPG-based QuitGuide app for smoking cessation.

2.2. Procedure

Study procedures were approved by the Fred Hutchinson Cancer Center Institutional Review Board. Eligibility criteria included daily smoking, smartphone access, and wanting to quit smoking. Exclusion criteria included being unable to read English, receiving smoking cessation treatment, having used QuitGuide in the past, or having a household member already enrolled in the study. Participants were recruited and screened for eligibility online. Interested and eligible participants were randomized 1:1 to receive an ACT-based smartphone application (iCanQuit) or a USCPG-based smartphone application (QuitGuide) for 12 months (citation removed for anonymized review). Randomization by permuted blocks of size 2, 4, and 6 was stratified by daily smoking frequency (≤20 vs. ≥21 cigarettes/day), minority race/ethnicity, education level (≤high school vs. ≥some college), and positive screening for depression (CESD-20 scale score ≤15 vs. ≥16).

2.3. Recruitment, enrollment, and Hispanic/Latinx subsample

Social media ads, specifically Facebook ads, were the primary source of recruitment for all trial participants, including Hispanic/Latinx participants (181/210, 86.3%), followed by a survey sampling company (21/210, 10.0%), friends or family (5/210, 2.4%), and search engine (3/210, 1.4%). The period of recruitment of all trial participants was May 2017 through September 2018. Data collection occurred between August 2017 through December 2019 via online self-reported study questionnaires at the 3-month, 6-month, and 12-month follow-ups. Participants were compensated for completed data collection at each follow-up, with up to $105 in total compensation per participant.

Compared to non-Hispanic/Latinx participants in the iCanQuit parent trial (citation removed for anonymized review), Hispanic/Latinx participants were younger (mean (SD) age = 34.5 (9.5) vs. 38.6 (10.9)), more likely to be male (49% vs. 28%), less likely to identify as White (57% vs. 70%), and less likely to live in a rural area (13% vs. 24%). Employment status and income did not differ between groups. Compared to non-Hispanic/Latinx participants in the iCanQuit parent trial, Hispanic/Latinx participants were more likely to report low educational attainment (high school diploma or less, 48% vs. 41%) and to screen positive for depression (56% vs. 48%). Hispanic/Latinx participants smoked fewer cigarettes per day, were less likely to be long-time smokers, and were less nicotine dependent compared with other participants.

2.4. Smartphone intervention apps

2.4.1. iCanQuit

Details of the iCanQuit app have been previously published (citations removed for anonymized review). Briefly, participants who had access to the ACT-based iCanQuit app for 12-months received eight levels of intervention content based on two key processes of ACT: acceptance of cravings to smoke and enactment of core life values that motivate living a smoke-free life (citation removed for anonymized review). In the “Preparing to Quit” phase, iCanQuit focuses on helping the user develop acceptance of physical sensations, emotions, and thoughts that trigger smoking, and allowing these triggers to pass without smoking via mindfulness and perspective taking. There is an “Urge Help” feature that is tailored to the type of trigger experienced by the user, as well as a tracking feature that encourages participants to track the number of cigarettes smoked and urges passed. In the “After You Quit” phase, iCanQuit focuses on helping the user stay motivated and preventing relapse.

2.4.2. QuitGuide

Details of the QuitGuide app have been previously published (citations removed for anonymized review). Briefly, the QuitGuide app developed by the National Cancer Institute is based on the US clinical practice guidelines (USCPG) for smoking cessation.⁴¹ QuitGuide is widely available and free to the public. Similar to iCanQuit, QuitGuide provides education and skills for preparing to quit and preventing relapse, as well as education on common triggers to smoke, barriers to cessation, and FDA-approved medications to aid cessation. Contrary to iCanQuit’s focus on acceptance, QuitGuide focuses on increasing motivation to quit by using logic and expectancies (e.g., providing information on the health consequences of smoking) and teaches skills for avoiding situations that lead to wanting to smoke.

2.5. Assessments

2.5.1. Baseline questionnaire

The baseline questionnaire included questions on socio-demographic characteristics and zip codes. Participants were screened for depression via Center for Epidemiological Studies Depression Scale (CESD-20).⁵¹ Participants were prompted about smoking habits, including how many cigarettes they smoked each day, history of smoking (years of smoking and past quit attempts), use of e-cigarettes in the past month, and whether people close to them also smoked (e.g., family and friends). Participants were assessed for level of nicotine dependence via the Fagerström Test for Cigarette Dependence (FTCD),⁵² their confidence in quitting smoking, and use of alcohol.

2.5.2. Smoking abstinence

Study questionnaires at the 3-month, 6-month, and 12-month follow-ups asked participants whether they abstained from cigarette smoking for the past 7 and 30 days, and the date of their last cigarette. Similar to the parent RCT (citations removed for anonymized review), the primary smoking cessation outcome was specified a priori as self-reported complete-case 30-day point-prevalence abstinence (PPA) at 12-months. Data were used to derive 12-month continuous prolonged abstinence for those who reported no smoking at all in the last 9 months. At the 12-month follow-up, participants were also asked if they abstained from the use of other nicotine-containing tobacco products (e-cigarettes, chewing tobacco, snus, hookahs, cigars, cigarillos, tobacco pipes, and kreteks).

2.5.3. Utilization and Satisfaction with the apps

Utilization of the apps was objectively measured via Google Analytics and included the number of times users interacted with their assigned app (i.e., number of logins), the time spent using the app per session, and the unique number of days of use. Participants self-reported on satisfaction with their assigned app via the 3-month follow-up survey.

2.5.4. Acceptance and Commitment Therapy (ACT) Processes and Mediation

The ACT-based acceptance of cues to smoke was assessed at baseline and 3-month follow-up via the Avoidance and Inflexibility Scale (AIS-27),⁵³ which has been validated among treatment seeking adults who smoke.^54,55 Scores are derived using the mean of the three 9-item subscales that assess one’s willingness to experience sensations, emotions, and thoughts that cue smoking without smoking. The items are rated on a 5-point scale from (1) “Not at all” to (5) “Very willing” and averaged, with higher scores indicating greater acceptance. A sample sensation item is “How willing are you to notice these bodily sensations without smoking?”, and items from the emotions and thoughts subscales are similar, substituting “feelings” or “thoughts” for “bodily sensations”. Pearson correlation coefficient between baseline measures of the acceptance subscales ranged from 0.52–0.67, but it was notably higher for the mean total (α = 0.74; 0.69, 0.79), indicating that the total acceptance scale was more precise than the subscales for this sub-analysis.

2.6. Statistical analyses

Participants’ socio-demographic characteristics and smoking behaviors were summarized by mean and standard deviation for continuous variables and frequency and percentages for categorical variables. To explore the efficacy of iCanQuit relative to QuitGuide for smoking cessation among Hispanic/Latinx participants, logistic regression models were used to compare reported 30-day abstinence from cigarette smoking at 12-months across study arms. Multiple imputation sensitivity analyses, with ten imputed datasets, were used to estimate effect size and standard errors for the 30-day abstinence from cigarette smoking endpoint at 12-months.⁵⁶ Second, generalized linear models were used to compare utilization of the apps across arms, and negative binomial models were used for any right-skewed count utilization data. Third, logistic regression models were used to compare how satisfied participants were with their assigned apps and outcome data retention rates across study arms. Finally, to evaluate whether increases in willingness to experience cues to smoke (e.g., acceptances of cues to smoke) without smoking mediated the effect of the intervention on reported 30-day abstinence from cigarette smoking at the 12-month follow-up, Hayes’s PROCESS macro for SAS was used.⁵⁷ We used two mediation models. The first mediation model tested baseline to 3-month changes in the three subscales of acceptance concurrently to examine which measure of acceptance may play a larger role in mediating the intervention effect. The second model tested mediation by baseline to 3-month change in the mean score for acceptance. Using this method with 5,000 bootstrapped samples, indirect effects were estimated and considered statistically significant when their bias-corrected 95% CI did not include zero. All models were adjusted for factors used in stratified randomization to avoid losing power and obtaining incorrect 95% CI.⁵⁸ These factors include daily smoking frequency, education, and positive screening for depression. Secondly, to reduce the potential for confounding, baseline characteristics were included in models as covariates if they differed by treatment group and were associated with the cessation outcome.^59,60 The R software version 4.0.3. was used for all other statistical analyses, including R libraries ‘MASS’ and ‘mice’ for negative binomial regression and multiple imputation analyses, respectively.^61–63 All statistical tests were 2-sided, with α=.05.

3. Results

3.1. Study enrollment and outcome data retention rates

The CONSORT diagram in Figure 1 illustrates the flow of Hispanic/Latinx participants through the study and the outcome data retention rates at each follow-up timepoint. The geographic location of all 210 participants enrolled into the trial across 32 US states is illustrated in Figure 2. A total of 28 (13%) participants resided in a rural residence in the US. Study outcome data retention rates were 83% at the 3-month follow-up, 85% at the 6-month follow-up, and 84% at the 12-month follow-up. Study data retention differed between arms at each follow-up: 3-months (77% iCanQuit vs. 89% QuitGuide, p=0.024); 6-months (81% iCanQuit vs. 90% QuitGuide, p=0.071); and 12-months (78% iCanQuit vs. 90% QuitGuide, p=0.021).

Figure 1.

CONSORT Diagram

^aTo increase enrollment of American Indians and Alaskan Natives (AIAN) and men, some non-AIAN and women who were eligible for study enrollment were randomly selected to be excluded.

^bRetention rates (%) were calculated as the number of participants who completed study data collection at each follow-up time point out of the total number of participants included in the imputed missing-as-smoking analysis.

Figure 2.

Geographic Location of Hispanic/Latinx Trial Participants

3.2. Participant characteristics

Participants were 34.5 years old, 51% female (Table 1). About half (48%) reported having a high school diploma or less education attainment, 55% were employed either full- or part-time, and 40% reported gross household incomes of $20,000 per year or less. More than half screened positive for depression (56%). About half (47%) were highly dependent on cigarette smoking (FTCD scores ≥6) and the majority (76%) reported smoking for ≥10 years. Most baseline characteristic and smoking behaviors were similar between arms. The only difference observed was that Hispanic/Latinx participants in the iCanQuit arm were more likely to be employed than those in the QuitGuide arm (65% iCanQuit vs. 46% QuitGuide, p=0.006).

Table 1.

Socio-demographic characteristics and smoking behaviors of Hispanic/Latinx participants

	No. (%) or Mean (SD)
Characteristic	n	Overall (n = 210)	QuitGuide (n = 105)	iCanQuit (n = 105)
Age, mean (SD), y	210	34.5 (9.5)	35.4 (9.7)	33.6 (9.2)
Female	210	103 (51%)	47 (45%)	56 (53%)
Race
White	210	119 (57%)	59 (56%)	60 (57%)
Black or African American	210	17 (8%)	11 (10%)	6 (6%)
American Indian or Alaska Native	210	10 (5%)	5 (5%)	5 (5%)
More than one race	210	29 (14%)	12 (11%)	17 (16%)
Unknown race	210	35 (17%)	18 (17%)	17 (16%)
Education
High school or less education	210	101 (48%)	53 (50%)	48 (46%)
Employment status
Employed	210	116 (55%)	48 (46%)	68 (65%)
Unemployed	210	30 (14%)	14 (13%)	16 (15%)
Homemaker	210	32 (15%)	18 (17%)	14 (13%)
Disabled	210	22 (10%)	19 (18%)	3 (3%)
Retired	210	4 (2%)	2 (2%)	2 (2%)
Other	210	6 (3%)	4 (4%)	2 (2%)
Income
<$20,000/year	210	83 (40%)	45 (43%)	38 (36%)
$20,000 - $54,999/year	210	100 (48%)	48 (46%)	52 (50%)
≥$55,000/year	210	27 (13%)	12 (11%)	15 (14%)
Married	210	59 (28%)	31 (30%)	28 (27%)
LGBT	210	46 (22%)	20 (19%)	26 (25%)
Rural residencea	210	28 (13%)	13 (12%)	15 (14%)
Depression positive screen resultsb	209	116 (56%)	60 (57%)	56 (54%)
Smoking behavior
FTCD score, mean (SD)	210	5.2 (2.0)	5.4 (2.1)	5.1 (2.0)
High nicotine dependence (FTCD score ≥6)	210	98 (47%)	52 (50%)	46 (44%)
Time to first cigarette within 5 minutes of waking	210	88 (42%)	44 (42%)	44 (42%)
Smokes more than one-half pack/d	210	115 (55%)	65 (62%)	50 (48%)
Smokes more than 1 pack/d	210	23 (11%)	13 (12%)	10 (10%)
Smoked for ≥10 years	210	160 (76%)	82 (78%)	78 (74%)
Used e-cigarettes at least once in past month	210	53 (25%)	20 (19%)	33 (31%)
Quit attempts in the past 12-months, mean (SD)	201	3.0 (14.4)	4.0 (19.8)	1.9 (4.6)
Confidence to quit smoking, mean (SD)c	210	66.4 (28.2)	66.3 (29.3)	66.6 (27.3)
Family and friends who smoke
Friends who smoke, mean (SD)	210	2.8 (1.7)	2.7 (1.7)	2.8 (1.7)
Number of housemates who smoke, mean (SD)	210	1.5 (1.0)	1.4 (1.0)	1.6 (1.1)
Partner who smokes, n (%)	210	65 (31%)	32 (30%)	33 (31%)
Alcohol use
Drinks per day on typical drinking day, mean (SD)	202	2.2 (3.8)	2.2 (4.0)	2.3 (3.6)
Heavy drinker, n (%)d	202	37 (18%)	19 (19%)	18 (18%)

Abbreviations: ACT, Acceptance and Commitment Therapy; FTCD, Fagerström Test for Cigarette Dependence; LGBT, lesbian, gay, bisexual, or transgender.

^aTo determine whether participants resided in urban or rural areas of the country, the R library ‘zipcode’⁷³ was used to link participants’ Zip codes to geographic location.

^bPositive screening results for depression via CESD-20; threshold ≥16.

^cRange, 0–100, where 0 indicates not at all confident and 100 indicates extremely confident.

^dHeavy drinking is defined as 4 or more drinks on a typical drinking day for women and 5 or more drinks on a typical drinking day for men within the past 30 days.⁷⁴

3.3. Rates of abstinence from cigarette smoking and tobacco use

Rates of smoking abstinence at each follow-up timepoint are shown in Table 2. At 12-months, Hispanic/Latinx participants who received the iCanQuit ACT-based intervention app reported higher rates of cigarette smoking abstinence compared to those who received the QuitGuide USCPG-based intervention app. (34% vs. 20%; OR=2.20; 95% CI: 1.10, 4.41). Multiple imputation sensitivity analyses showed similar rates of cigarette smoking abstinence at 12-months (35% vs. 20%; OR=2.26; 95% CI: 1.15, 4.48). Although the missing-as-smoking analyses showed descriptively higher rates of smoking abstinence for iCanQuit participants, these were not statistically significantly different from QuitGuide participants (27% vs. 18%; OR=1.68; 95% CI: 0.87, 3.27). The odds of continuous prolonged abstinence from cigarette smoking were 3.25 times higher among Hispanic/Latinx participants who received the iCanQuit app compared with those who received the QuitGuide app (21% vs. 8%; OR=3.25; 95% CI: 1.11, 9.57). iCanQuit participants were also more likely to report abstaining from using other nicotine-containing products, including e-cigarettes, but this rate was not significantly higher than among QuitGuide participants (28% iCanQuit vs. 18% QuitGuide, p=0.104).

Table 2.

Rates of smoking abstinence by follow-up time point

	No. (%)
Variable	Overall (N = 210)	QuitGuide (n = 105)	iCanQuit (n = 105)	OR (95% CI)	p value
12-month endpoints
30-d PPA	47/176 (27%)	19/94 (20%)	28/82 (34%)	2.20 (1.10, 4.41)	0.026
30-d PPA, multiple imputation	574/2100 (27%)	206/1050 (20%)	368/1050 (35%)	2.26 (1.15, 4.48)	0.020
30-d PPA, missing-as-smoking	47/210 (22%)	19/105 (18%)	28/105 (27%)	1.68 (0.87, 3.27)	0.124
7-d PPA	64/176 (36%)	29/94 (31%)	35/82 (43%)	1.62 (0.86, 3.04)	0.135
Continuous prolonged abstinencea	18/131 (14%)	6/73 (8%)	12/58 (21%)	3.25 (1.11, 9.57)	0.032
30-d PPA of nicotine-containing productsb	40/176 (23%)	17/94 (18%)	23/82 (28%)	1.83 (0.88, 3.77)	0.104
6-month endpoints
30-d PPA	40/179 (22%)	17/94 (18%)	23/85 (27%)	1.74 (0.85, 3.58)	0.131
7-d PPA	56/179 (31%)	24/94 (26%)	32/85 (38%)	1.87 (0.97, 3.59)	0.060
3-month endpoints
30-d PPA	23/174 (13%)	10/93 (11%)	13/81 (16%)	1.73 (0.70, 4.32)	0.238
7-d PPA	43/174 (25%)	17/93 (18%)	26/81 (32%)	2.33 (1.13, 4.79)	0.022

Abbreviations: OR, odds ratio; PPA, point prevalence abstinence.

^aDefined as no smoking since 3-months post-randomization, using self-reported date of last cigarette.

^bIncluding any kind of e-cigarettes or vaping, chewing tobacco, snus, hookahs, cigars, cigarillos, tobacco pipes, and kreteks.

3.4. Utilization of intervention apps and satisfaction

Data on the utilization of intervention apps and reported satisfaction with the apps can be found in Table 3. Hispanic/Latinx participants who received the iCanQuit ACT-based intervention app utilized their assigned app more frequently than those who received the QuitGuide USCPG-based intervention app, as objectively measured by (1) number of logins (22.4 vs. 7.3, p<0.001), (2) time spent using the app (3.7 vs. 2.3 minutes per session, p=0.002), and (3) total number of unique days using the app (14.5 vs. 6.0, p<0.001). Hispanic/Latinx participants who received the iCanQuit ACT-based intervention app were also generally more satisfied with their assigned app than those who received the QuitGuide USCPG-based intervention app. For example, when asked “overall, how satisfied were you with your assigned app?”, iCanQuit participants were significantly more likely to report being satisfied with their app compared with QuitGuide participants (90% iCanQuit vs. 79% QuitGuide, p=0.043). Hispanic/Latinx participants who received the iCanQuit ACT-based intervention app were also more likely to report that their app was useful for quitting smoking (83% vs. 69% QuitGuide, p=0.035). When asked “would you recommend your app to a friend who would like to quit smoking”, iCanQuit participants were descriptively more likely than QuitGuide participants to recommend the app for quitting smoking (86% vs. 74%, p=0.053) and descriptively more likely to report they felt the application was made for them (81% vs. 69%, p=0.061).

Table 3.

Utilization and satisfaction of the assigned smartphone app

		Mean (SD) or No. (%)
Variable	n	Overall (N = 210)	QuitGuide (n = 105)	iCanQuit (n = 105)	IRR, Point Estimate or Odds Ratio (95% CI)	p value
Utilization of apps at 6-monthsa, Mean (SD)
Number of times apps were opened	207	14.8 (28.3)c	7.3 (7.9)d	22.4 (37.9)e	IRR: 3.04 (2.20, 4.19)	<.001
Minutes spent using the app per session	195	3.0 (3.2)f	2.3 (1.8)g	3.7 (4.0)h	PE: 1.4 (0.5, 2.3)	0.002
Number of unique days of app use	207	10.2 (17.5)i	6.0 (6.4)i	14.5 (23.2)d	IRR: 2.45 (1.79, 3.35)	<.001
Satisfaction at 3-months, No. (%)
Satisfied with assigned app	163	137 (84%)	68 (79%)	69 (90%)	OR: 2.60 (1.03, 6.56)	0.043
App was useful for quitting	164	124 (76%)	60 (69%)	64 (83%)	OR: 2.26 (1.06, 4.83)	0.035
Would recommend assigned app	166	132 (80%)	66 (74%)	66 (86%)	OR: 2.23 (0.99, 5.05)	0.053
Felt app was made for me	162	121 (75%)	58 (69%)	63 (81%)	OR: 2.05 (0.97, 4.32)	0.061

Abbreviations: IRR, incident rate ratio; OR, odds ratio; Point Estimate, PE.

^aA full 6-months of utilization data from Google Analytics were available for n=207/210, 99%.

^cmedian = 6;

^dmedian = 5;

^emedian = 7;

^fmedian = 2.1;

^gmedian = 1.7;

^hmedian = 2.6;

ⁱmedian = 4.

3.5. Change in Acceptance and Commitment Therapy (ACT) Processes and Mediation

Hispanic/Latinx participants who received the iCanQuit ACT-based intervention app reported significantly greater increases in all three subscales of ACT-based processes (i.e., sensations, emotions, and thoughts that cue smoking) from baseline to 3-months than those who received the QuitGuide USCPG-based intervention app (all p<0.01) (Table 4). Mediation analyses including the three separate subscales of ACT-based processes in a single model did not show significant evidence of mediation. Mean acceptance score, which includes all three subscale scores simultaneously, did significantly mediate the intervention effect on long-term smoking abstinence at the 12-month follow-up (p<0.05).

Table 4.

Change in ACT-based acceptance processes from baseline to 3-months as mediators of the effect of the intervention on reported 30-day abstinence from cigarette smoking at the 12-month follow-up^{a, b}

		Mean (SD)
Mediator	n	Overall (N = 210)	QuitGuide (n = 105)	iCanQuit (n = 105)	Point estimate for difference (95% CI)	p value	Estimate of mediation effect (95% CI)
Acceptance to internal cues to smoke Sensations, mean (SD)
Baseline	207	3.07 (0.54)	3.07 (0.54)	3.08 (0.55)
3-months	162	3.24 (0.67)	3.10 (0.66)	3.39 (0.66)
Change from baseline to 3-months	160	0.16 (0.78)	0.05 (0.73)	0.29 (0.83)	0.28 (0.08, 0.49)	0.008	0.08 (−0.45, 0.47)
Emotions, mean (SD)
Baseline	209	2.88 (0.44)	2.89 (0.42)	2.86 (0.45)
3-months	167	3.06 (0.59)	2.90 (0.53)	3.23 (0.61)
Change from baseline to 3-months	166	0.19 (0.69)	0.04 (0.62)	0.37 (0.72)	0.33 (0.16, 0.51)	<0.001	0.59 (−0.02, 1.67)
Thoughts, mean (SD)
Baseline	208	2.87 (0.44)	2.87 (0.42)	2.87 (0.46)
3-months	169	2.99 (0.57)	2.87 (0.53)	3.13 (0.57)
Change from baseline to 3-months	167	0.12 (0.62)	0.01 (0.55)	0.24 (0.67)	0.24 (0.08, 0.40)	0.004	−0.07 (−0.67, 0.40)
Mean score, mean (SD)
Baseline	206	2.94 (0.41)	2.94 (0.39)	2.94 (0.42)
3-months	162	3.10 (0.54)	2.95 (0.48)	3.26 (0.56)
Change from baseline to 3-months	159	0.17 (0.59)	0.03 (0.50)	0.32 (0.64)	0.31 (0.15, 0.47)	<0.001	0.52 (0.24, 1.01)*

Abbreviations: ACT, Acceptance and Commitment Therapy.

^aAvoidance and Inflexibility Scale scores at baseline and 3-months range from 1 to 5. Higher scores indicate greater acceptance.

^bChanges in acceptance scores were calculated as follow-up at 3-months minus baseline, ranging from −4 to 4.

^*p<0.05.

4. Discussion

We found for the first time that a remotely app-delivered intervention based on Acceptance and Commitment Therapy (ACT) may be efficacious for helping Hispanic/Latinx adults abstain from cigarette smoking. Hispanic/Latinx participants assigned to the ACT-based iCanQuit app had over two times higher odds of abstinence from cigarette smoking at the 12-month follow-up than those assigned to the USCPG-based QuitGuide app (34% vs. 20%; OR=2.20; 95% CI: 1.10, 4.41). Compared to the broader literature of traditional clinic-based in-person smoking cessation interventions among Hispanic/Latinx adults who smoke with 6-month or longer follow-ups, quit rates have ranged between 8% and 37.5%.^64–68 Thus, the higher quit rates for the iCanQuit app, notably without the provision of coaching or pharmacotherapy, show great promise.

iCanQuit participants also utilized their app more frequently and reported higher levels of satisfaction with their assigned app than those assigned to the USCPG-based QuitGuide app. Hispanic/Latinx participants who received the iCanQuit app were somewhat more likely to report that that they felt the app was made for them than those who received the QuitGuide app (81% iCanQuit vs. 69% QuitGuide, p=0.06). These results suggest that ACT-based interventions’ focus on acceptance of one’s own smoking triggers and tailoring to personal values may be more universally appealing and may have helped Hispanic/Latinx participants feel like the app was made for them. Since this is a secondary analysis of a subsample of Hispanic/Latinx adults who smoke, future ACT-based smoking cessation research that focuses on this population is needed to confirm these results.

This study also provides, for the first-time, empirical evidence that learning key ACT processes helped Hispanic/Latinx adults who smoke quit via increases in willingness to tolerate physical sensations, emotions, and thoughts to smoke without smoking. This analysis showed that the effect of treatment on cessation outcomes was not significantly mediated via increases in any one subscale, but through the mean score of acceptance (i.e., sensations, emotions and thoughts subscales combined). The internal consistency of the mean score of acceptance was notably higher than the subscales, indicating that the acceptance scale may function better as a whole rather than in subscales. More broadly, the mediation results in this study suggest that future intervention development focusing equally on these three ACT-based core processes may be a fruitful avenue for developing tailored smoking cessation interventions for this population.

Learning how to allow cravings to smoke to come and go by applying mindfulness techniques and perspective taking may have contributed to the three times higher odds of 9-month continuous abstinence for participants receiving iCanQuit as compared to those receiving QuitGuide. These findings broadly align with past work on smoking-specific experiential avoidance, which generally show that decreasing this avoidance is a mediator of cessation outcome.⁶⁹ Future studies could further evaluate whether this key ACT processes of acceptance could help other highly nicotine-dependent Hispanic/Latinx individuals offset withdrawal symptoms, thereby improving long-term smoking abstinence.

Among the few published digital interventions (i.e., social media and text messaging) for smoking cessation that have focused on the Hispanic/Latinx population,^32–35 all were feasibility or pilot studies limited by small sample size and single-arm designs. Therefore, the present study addressed many of the limitations of the prior research on digital smoking cessation interventions in this population. First, this study recruited Hispanic/Latinx adults who smoke from 32 US states, including in states with high proportions of Hispanic/Latinx populations (i.e., CA, FL, TX), thereby demonstrating potential for broad reach and geographic generalization of results. Second, a high proportion of study participants (84%) provided study outcome data at the 12-month follow-up. Third, 30% rates of abstinence from cigarette smoking were achieved without the provision of medication to aid cessation or human counseling, thereby demonstrating potential for dissemination of low-touch digital interventions at low-cost.

There are important study limitations. First, post hoc subgroup analysis can be biased by chance results and thus should be viewed with caution.^59,60 Second, the differential attrition rates between arms at 12-months (22% iCanQuit vs. 10% QuitGuide) should be noted. The differential attrition in this subsample of Hispanic/Latinx adults may be a false positive result due to sampling error. Additionally, the observed differential attrition rates likely biased the nonsignificant missing-as-smoking quit rates between arms, favoring the arm with less attrition.^70,71 Therefore, the missing-as-smoking results should also be viewed with caution. Third, the subset of Hispanic/Latinx participants in this study were all English speakers and therefore, the results may not be representative of the full population of Spanish-speaking Hispanic/Latinx adult smokers in the US or those who are not daily smokers. Finally, self-reported abstinence from cigarette smoking was not biochemically verified given the methodological challenges associated with biochemical confirmation of smoking status in large population-based studies. And while the external validity of the self-reported smoking outcome remains unknown, given the randomized design, we see no compelling reason that the validity of the results would differ between study arms.

The findings of this study have important implications for designing future interventions to help the population of Hispanic/Latinx adults who smoke quit. First, evidence-based interventions that are delivered digitally could provide a viable option to those who lack access to smoking cessation treatments, such as those without health insurance. Second, app-delivered evidence-based interventions help address key accessibility barriers to receiving treatment (e.g., transportation, time). Future smoking cessation interventions for Hispanic/Latinx adults who smoke could also be made available in Spanish, thereby increasing the reach to other Hispanic/Latinx subgroups who are Spanish speakers such as Puerto Ricans living in Puerto Rico (US territory) as well as addressing Spanish language barriers associated with pooper health in this population.⁷² Future studies could also evaluate relevant cultural and social factors that may influence Hispanic/Latinx adults who smoke’s response to the intervention, such as country of origin, acculturation status, number of years in the US, ethnic orientation, and racial or ethnic discrimination. Tailoring of the intervention to increase cultural sensitivity in this population may help further increase satisfaction and engagement with the intervention, thereby improving outcomes.

This paper provides first-time empirical evidence that there is high acceptability of smartphone apps to engage and enable US Hispanic/Latinx adults who smoke quit smoking. Importantly, willingness to accept cravings to smoke without smoking, a key process of ACT, mediated the effect of the intervention on long-term abstinence from cigarette smoking. Therefore, these results support the potential efficacy of ACT-based digital interventions to help Hispanic/Latinx adults who smoke quit. Now needed is the development and testing of an ACT-based app-delivered smoking cessation intervention tailored to the US population of Hispanic/Latinx adults who smoke and focuses on enhancing intervention components that teach skills to accept cues to smoke.

• Smartphone interventions can help Hispanic/Latinx adults quit smoking.

• iCanQuit yielded greater abstinence of cigarette smoking than QuitGuide.

• iCanQuit was more utilized and highly rated compared to QuitGuide.

Abbreviations:

ACT

Acceptance and Commitment Therapy

CI

95% confidence interval

FTCD

Fagerström Test for Cigarette Dependence

GED

General Education Development

LGBT

lesbian, gay, bisexual, or transgender

OR

odds ratio

PPA

point-prevalence abstinence

RCT

randomized controlled trial

US

United States

USCPG

US Clinical Practice Guidelines

Data sharing statement.

The data will be shared on reasonable request to Jonathan B. Bricker at jbricker@fredhutch.org.