Step 1: The search of listed databases provided a total of 1989 articles. After adjusting publication types and written languages, 447 articles remained. Of these, 349 articles were discarded because after reviewing the abstracts, these articles did not meet the inclusion criteria. By the end of title and abstract review, 98 articles were imported into the Endnote reference management system, where 28 duplicate articles were identified and excluded. The full text of the remaining articles was examined in detail. Sixty-one studies did not meet the inclusion criteria as described leaving only eight studies in the systematic literature review. No additional studies were identified by checking the references of located, relevant papers and searching for studies that have been cited by included studies. No unpublished studies were obtained. The flow diagram of articles selection is shown in Figure 1. The following table (Table 2) summarises the details of the reviewed studies.
Table 2: Details of the Reviewed Studies
Source
|
Study Design
Participant
|
Interventions and Follow-up
|
Outcomes and Measures
|
Hertzberg et al. 2013[81]
|
Pilot RCT
Smokers with PTSD (n=22)
|
Intervention: mCM (app) and two smoking cessation counselling sessions, nicotine replacement, and bupropion (n=11)
Control: non-app conditions (n=11)
Follow-up: Three months
|
Adherence: Compliance with trial activities
Smoking status: CO-verified 7-day PPA at 4-week and 3-month follow-up
|
Vilardaga et al. 2016 [82]
|
Qualitative study
Individuals with a history of serious mental illness (n=5)
|
Day 1: introduced participants to QuitPal (app) with a brief hands-on demonstration and explain its functions
Day 2-3: participants field-tested QuitPal and interacted with the app to gain a more in-depth user experience
Follow-up: Three days
|
Adherence: App usage logs
User experience: Interview and SUS questionnaire
|
Hicks et al. 2017 [83]
|
Pilot RCT
Smokers with PTSD (n=11)
|
Intervention: QUIT4EVER, an intervention combining mobile contingency management smoking cessation counselling and medications, and the SCQ app (n=5)
Control: a contact control condition that was identical to QUIT4EVER except SCQ app was not included (n=6)
Follow-up: Six months
|
Smoking status: Self-reported prolonged smoking abstinence
User experience: Perceived effectiveness on a Likert scale questionnaire
|
Minami et al. 2018 [69]
|
Pilot trial
Smokers with psychiatric disorders (have a depressive disorder or bipolar disorder) (n=8)
|
A smartphone intervention app that prompts participants to practice mindfulness (listening to an audio recording on the smartphone five times per day), complete EMA reports five times per day, and submit CO videos twice per day
Follow-up: Three months
|
Adherence: Compliance with trial activities
Smoking status: CO-verified 7-day PPA at 2-, 4-week, and 3-month post-quit follow-ups, and Cigarettes use reduction
User experience: Satisfaction to the programme questionnaire
|
Heffner et al. 2019 [84]
|
Pilot trial
Daily smokers with mild to moderate depressive symptoms (n=16)
|
Smokefree TXT along with Actify! (app) to provide cessation content that had not yet been built into the app for this pilot testing
Follow-up: Six weeks
|
Adherence: Number of log-ins per participants and reported usability challenges
Mental health status: Depressive symptoms measured by the PHQ
Smoking status: CO-verified, 7-day and 30-day PPA at 6-week follow-up
User experience: Interview
|
Herbst et al. 2019 [68]
|
Qualitative study
US military veterans with PTSD who smoked at least five cigarettes per day for 15 of the past 30 days and stated an interested in cessation (n=20)
|
Use of the SQC app
Follow-up: Three months
|
Adherence: Retention
User experience: Comfort levels with mobile technology (baseline measure) - the PMPIQ-P and Interview
|
Wilson et al. 2019 [85]
|
Qualitative study
Smokers with schizophrenia, schizoaffective, or psychotic disorders) two cohorts (Cohort 1 n=5, Cohort 2 n=8, total n=13)
Therapists (n=2)
|
The intervention included mobile contingency management (i.e., financial compensation for confirmed abstinence from smoking), pharmacotherapy for smoking cessation, cognitive- behavioural counselling sessions, and the use of SQC app for relapse prevention
Follow-up: Three months
|
Adherence: Compliance with treatment
Smoking status: Self-reported smoking abstinence
User experience: Interview Perception of usefulness
|
Alyssa et al. 2020 [86]
|
RCT
Smokers with diagnosed mental health illness (n=34)
|
Intervention: mobile CM (i.e. monetary compensation for bio-verification of abstinence through using a phone app), CBT, and pharmacotherapy for smoking cessation (n=21)
Control: ITC, which contained all components except the CM (n=13)
Follow-up: Six months
|
Acceptability: A questionnaire assessing eight self-reported items
Feasibility: A questionnaire that was completed by the therapist about the participant
Knowledge of treatment: A tailored questionnaire
Smoking status: Self-reported prolonged abstinence, Bio-verified (including saliva and CO verification) prolonged abstinence at 6-month follow-up, 7-day and 30-day self-reported PPA
|
SUS: System Usability Scale
PPA: Point Prevalence Abstinence
PHQ: Patient Health Questionnaire
PTSD: Post-Traumatic Stress Disorder
PMPIQ-P: Perceptions of Mobile Phone Interventions Questionnaire–Patient (version)
EMA: Ecological Momentary Assessment
CO: Carbon Monoxide
CBT: Cognitive Behavioural Therapy
ITC: Intensive Treatment Comparison
All eight reviewed articles were published in English from the United States. Two of these articles reported pilot randomised controlled trials (RCTs), three reported qualitative studies, two reported pilot trials, one reported a full RCT and one reported a development study. The duration of studies ranged from three days to six months. The studies involved a total of only 131 participants. The main inclusion criteria entailed adults (18 years or older), smokers (smoke one or more cigarettes or using other types of tobacco products in a daily basis), with mental health issues, and using a smartphone. The studied intervention in the reviewed articles is smoking cessation app for smokers with mental health issues.
The primary outcome of six reviewed studies was smoking status of participants. Smoking status was measured in different ways, including self-reported smoking abstinence and biochemical verification of smoking abstinence with different follow-up. Four studies reported smoking abstinence with biochemical verification [69, 81, 84, 86]. The duration of abstinence ranged from 7-day to 30-day. Secondary outcomes of reviewed studies included adherence, user experience, participant mental health status, acceptability and feasibility of the intervention.
Six studies concluded that smoking cessation apps support smokers with mental health conditions to quit smoking [69, 81, 83-86]. However, none of these studies had conclusive findings on the effectiveness of smoking cessation apps. User experience of smoking cessation apps varied across different studies [68, 69, 82-85]. The majority indicated smoking cessation apps achieved positive user experience, while one study stated that the smoking cessation app scored five points below industry standard (65.5 out of 100) on the user experience measuring scale [82]. The same study found that some features of smoking cessation app are redundant and rarely used [82]. Six studies measured participants' adherence to intervention activities. The majority of these studies reported a high compliance level of participants to intervention [68, 69, 81, 82, 84], while one reported low compliance [85]. Only one study measured participants' mental health status [84]. This study indicated that the use of smoking cessation app lead to a significant decrease in depressive symptoms among app users [84].
Due to the diversity of study designs, participants, interventions, and outcome measures, and high risk of bias (Table 3), a meta-analysis of these studies was not appropriate [87].
Table 3: Risk of biases of the reviewed studies
Source
|
Selection bias
|
Performance bias
|
Attrition bias
|
Other bias
|
Hertzberg et al. 2013 [81]
|
Low
|
High
|
Low
|
1. Small sample size
2. Short follow-up period
3. Did not ask participants if they were receiving any PTSD treatment
4. Did not measure PTSD symptoms change
|
Vilardaga et al. 2016 [82]
|
High
|
NA
|
Low
|
1. Limited understanding of participants' psychiatric status (before and after intervention)
2. Limited time using the app
3. Interviewer's characteristics (e.g. gender, investigator role) could have influenced study procedures and interview results
|
Hicks et al. 2017 [83]
|
Low
|
High
|
Low
|
1. Small sample size
2. Aspects of the current study underscore the potential for behavioural mobile health apps to promote long-term abstinence in smokers with PTSD
3. Smoking status relied on self-reported data
|
Minami et al. 2018 [69]
|
High
|
High
|
Low
|
1. Small sample size
2. The generalisation of these findings to other populations may be limited as all participants in this study were of low socioeconomic status
|
Heffner et al. 2019 [84]
|
Low
|
High
|
Low
|
1. Small sample size
2. Study design: lack of a control group
3. Potential confounding effect: did not track non-study treatment use
4. Selection bias: sample, on average, was of high socioeconomic status, had a low level of nicotine dependence, and only included smokers with mild to moderate depression
|
Herbst et al. 2019 [68]
|
High
|
NA
|
Low
|
1. Sample men exclusively from urban and suburban areas
2. The study did not examine the efficacy of the app
3. The study relied on self-report data of app usage
4. Potential of the therapeutic alliance that makes biased answers in interviews
5. The study did not include specific questions about use of the app to cope with PTSD symptoms
|
Wilson et al. 2019 [85]
|
Low
|
NA
|
High
|
1. Smoking status relied on self-reported data
|
Alyssa et al. 2020 [86]
|
Low
|
High
|
Low
|
1. Small sample size
2. Unable to detect which treatment components determined the smoking cessation effect
3. There was no post-treatment assessment to the control group, while the intervention group had bio-verified data at post-treatment
|
Three studies had a high risk of selection bias - specific population groups (e.g. mental health smokers from high socioeconomic status) were invited to take part in these studies, leading to a lack of generalisability of the study results [68, 69, 82]. All reviewed trials had a high risk of performance bias because blinding was not performed by researchers or trial participants in any of these trials [69, 81, 83, 84, 86]. Majority of reviewed studies have small sample sizes and failed to detect a statistically significant smoking cessation outcome [69, 81, 83, 84, 86]. All studies had short to medium length of follow-up. Two studies had a six-month follow-up, while the other studies had less than three-month follow-up. The reviewed studies could not detect the long-term impacts of smoking cessation apps on smokers with mental health conditions. Two reviewed studies have no post-treatment assessment to the control group, which made it impossible to identify the size of the effect of the evaluated interventions [84, 86].
Step 2: Five smoking cessation apps for smokers with mental health conditions were identified from the reviewed studies. Details of these apps (both from literatures and app store search) are summarised in Table 4. All were built based on theories and clinical guidelines. Three had their development methods and processes discussed in the reviewed articles. Four focused on smokers with mental health conditions while one targeted all smokers. Two apps include functions for both smoking cessation and mental health management, but three had only functions for smoking cessation. Only two apps found in the systematic review were available in both Apple and Google App stores, two were only available in Apple App store, and one was not mentioned (no clarification of its availability in app stores). Two apps include the keyword “quit” in their name.
By searching these apps in app stores, three of them are unavailable in Apple or Google App store, one is available for free in Apple app store, while one is available free in both Apple and Google App stores. Only one app has its download rate available in the Google App store, the app named Stay Quit Coach has been downloaded over 10,000 times in the Google App store. The user rating scores are only available to two literature-based apps. The app named Actify! has its user rating score of 1.5 out of 5.0 in the Apple App store, while it was only rated by four users. Stay Quit Coach was rated as 3.5 out of 5.0 (No. of reviewers = 2) in the Apple App store and rated as 4.0 out of 5.0 (No. of reviewers = 21) in the Google App store.
Table 4: Details of apps identified from the reviewed studies
Source
|
App names
|
Grounding theories
|
Development methods
|
Target users
|
Smoking cessation features
|
Mental health features
|
No. of downloads
App store rating (n= No. of user rated)
|
Cost in NZD$
|
1
|
2
|
3
|
4
|
5
|
6
|
7
|
other
|
Vilardaga et al. 2016 [82]
|
QuitPal (Apple and Google)
|
USPHSCPG
|
Iterative development
|
Smokers
|
✓
|
✓
|
|
|
✓
|
✓
|
✓
|
1. Social support
2. Contact to Quitline
|
|
NA
|
Minami, et al. 2018 [69]
|
-
|
CM and EMA
|
-
|
Smokers with psychiatric disorders
|
|
|
|
✓
|
|
|
|
Bio-verification on quitting data
|
1. Mental health practice
2. Prompt to complete EMA reports
|
NA
|
Heffner et al. 2019 [84]
|
Actify!
(Apple)
|
BAT-D and BATS
|
User-centred design process including competitive analysis, focus groups, and usability testing of low- and high-fidelity prototypes
|
Smokers with depressive symptoms
|
|
✓
|
|
|
|
|
✓
|
Quitting plan
|
|
Download rate unavailable
1.5/5.0 (n=4)
|
Free
|
Hicks et al. 2017 [83]
|
Stay Quit Coach (SQC) (Apple and Google)
|
CBT and USPHSCPG
|
The app is part of the integrated care (IC) treatment protocol, which consists of combined behavioural and pharmacotherapy treatment
|
Smokers with PTSD
|
|
|
|
|
✓
|
✓
|
|
1. Quitting plan
2. Contact to Quitline
|
1. Mental health practice (reduce anxiety sensitivity and hyperarousal)
2. Help users to cope with negative emotions
|
Download:
Apple-unavailable
Google-10,000+
User rating:
Apple-3.5/5.0 (n=2)
Google-4.0/5.0 (n=21)
|
Free
|
Herbst et al. 2019 [68]
|
Wilson et al. 2019 [85]
|
Hertzberg et al. 2013 [81]
|
mCM
(Apple)
|
CM
|
-
|
Smokers with PTSD
|
|
|
|
|
|
|
|
1. Bio-verification on quitting data
2. Compensation to quitting behaviours
|
|
NA
|
Alyssa et al. 2020 [86]
|
USPHCPG
|
US Public Health Service's Clinical Practice Guideline for Treating Tobacco Use and Dependence
|
EMA
|
Ecological momentary assessment
|
CM
|
Contingency management
|
BAT-D
|
Behavioural Activation Treatment for Depression
|
BATS
|
Behavioural Activation Treatment for Smoking
|
CBT
|
Cognitive Behaviour Therapy
|
PTSD
|
Posttraumatic Stress Disorder
|
1
|
Calculator
|
2
|
Calendar
|
3
|
Gamification
|
4
|
Hypnosis
|
5
|
Information
|
6
|
Lung Health Tester
|
7
|
Rationing
|
Table 5: Details of apps found from the Apple and Google App Stores
App names
|
Developer
Grounding theories
Development methods
|
Target users
Category
|
Smoking cessation features
|
Mental health features
|
No. of downloads
App store rating (n= No. of user rated)
|
Cost in NZD$
|
1
|
2
|
3
|
4
|
5
|
6
|
7
|
other
|
|
|
|
Apple App Store - "Mental health smoking."
|
LIFEGIFT HERE4U
|
LifeGift Pte. Ltd.
NA
NA
|
Smokers
Health and fitness
|
|
|
|
|
✓
|
|
|
|
|
NA
NA
|
$1.69 (in-app purchase)
|
Construction Industry Helpline
|
Construction Industry Solutions Limited
NA
NA
|
Construction worker with any of the four areas of need: mental, physical, financial and social health
Lifestyle
|
|
|
|
|
✓
|
|
|
|
1. An assessment tool to evaluate conditions
2. Self-help tools to cope with conditions
|
NA
NA
|
NA
|
Apple App Store - "Mental health."
|
Daylio Journal
|
Relaxio s.r.o.
NA
Principles: help users being mindful, identify the influence of new hobby, easy-to-use
|
Everyone
Lifestyle
|
|
|
|
|
|
|
|
|
1. Calendar
2. Diary
3. Mood tracking
4. Prompt goals setting (include mood and health behaviours)
|
NA
4.7 out of 5.0 (n=452)
|
$4.99 to $39.99 (in-app purchase, depending on the package)
|
Morning! – A 5 Minute Journal
|
Adriana Padilla
NA
NA
|
Everyone
Lifestyle
|
|
|
|
|
|
|
|
|
1. Calendar
2. Daily quotes
3. Diary
4. Mood tracking
5. Reminders
|
NA
4.9 out of 5.0 (n=12)
|
$9.99 (in-app purchase)
|
Wysa: Mental Health Support
|
Touchkin
CBT, DBT, Yoga and meditation
NA
|
Everyone
Health & Fitness
|
|
|
|
|
|
|
|
|
1. Chatbot communication supports
2. Contact to therapists
3. Self-help tools to cope with conditions
|
NA
4.7 out of 5.0 (n=34)
|
$8.49 to $119.99 (in-app purchase, depending on package)
|
MindDoc: Depression & Anxiety
|
MindDoc Health GmbH
NA
Developed with psychotherapists and scientists
|
Everyone
Medical
|
|
|
|
|
|
|
|
|
1. Information
2. Mental health practice (course)
3. Mood tracking
|
NA
4.7 out of 5.0 (n=281)
|
$7.49 to $76.99 (in-app purchase, depending on the package)
|
Stoic. Mental health journal
|
Maciej Lobodzinski
Stoicism
NA
|
Everyone
Health & Fitness
|
|
|
|
|
|
|
|
|
1. Calendar
2. Diary
3. Daily quotes
|
NA
4.7 out of 5.0 (n=93)
|
$10.99 to $159.99 (in-app purchase, depending on the package)
|
Apple App Store – “Quit smoking.”
|
Quit smoking--~
|
Dennis Ebbinghaus
NA
NA
|
Smokers
Health & Fitness
|
|
✓
|
✓
|
|
✓
|
|
✓
|
1. Craving supports
2. Goal setting
|
|
NA
4.5 out of 5.0 (n=28)
|
$1.99 to $46.99 (in-app purchase, depending on the package)
|
Smoke-Free – Stop Smoking Now
|
David Crane
30+ proven quit smoking techniques and the most reliable quitting methods science
NA
|
Smokers
Health & Fitness
|
✓
|
✓
|
✓
|
|
✓
|
|
|
Goal setting
|
|
NA
4.7 out of 5.0 (n=1,125)
|
$1.69 to $49.99 (in-app purchase, depend on package)
|
My QuitBuddy
|
Australian National Preventive Health Agency
NA
NA
|
Smokers
Health & Fitness
|
✓
|
✓
|
|
|
|
|
|
Social support
|
|
NA
5.0 out of 5.0 (n=22)
|
NA
|
Quit Genius – quit smoking
|
Digital Therapeutics Ltd
CBT
NA
|
Smokers
Health & Fitness
|
✓
|
|
|
|
|
|
|
1. Reminders
2. Quitting exercise
|
|
NA
4.5 out of 5.0 (n=3,100)
|
$10.99 to $149.99 (in-app purchase, depend on package)
|
Kwit - Quit smoking and vaping
|
KWIT
CBT
NA
|
Smokers
Health & Fitness
|
|
✓
|
✓
|
|
|
|
✓
|
Motivational messages
|
|
NA
4.6 out of 5.0 (n=5)
|
$2.49 to $89.99 (in-app purchase, depend on package)
|
Google App Store – "Mental Health Smoking"
|
Quit Tracker: Stop Smoking
|
despDev
NA
NA
|
Smokers
Health & Fitness
|
✓
|
✓
|
✓
|
|
|
|
|
|
|
1,000,000+
4.7 out of 5.0 (n=100,413)
|
$3.99 (in app purchase)
|
Smoke Free, stop smoking now and quit for good
|
David Crane
30+ proven quit smoking techniques and the most reliable quitting methods science
NA
|
Smokers
Health & Fitness
|
✓
|
✓
|
✓
|
|
✓
|
|
|
Goal setting
|
|
1,000,000+
4.8 out of 5.0 (n=52,631)
|
$1.69 to $47.99 (in-app purchase, depend on package)
|
Guided Mental Health Journal - Iona Mind
|
Iona Mind - Mental Health Support
CBT and performance psychology
NA
|
Everyone
Health & Fitness
|
|
|
|
|
|
|
|
|
1. Diary
2. Information (CBT)
3. Mood tracking
4. Mental health practice
5. Goal setting
|
1,000+
4.8 out of 5.0 (n=94)
|
$7.99 to $89.99 (in-app purchase, depending on the package)
|
Stop Smoking - EasyQuit free
|
Mario Herzberg (Hanna)
NA
NA
|
Smoker
Health & Fitness
|
✓
|
|
✓
|
|
✓
|
|
✓
|
Quitting plan
|
|
1,000,000+
4.8 out of 5.0 (n=78,056)
|
$7.99 to $89.99 (in-app purchase, depend on package)
|
Wysa: stress, depression & anxiety therapy chatbot
|
Touchkin
CBT, DBT, Yoga and meditation
NA
|
Everyone
Health & Fitness
|
|
|
|
|
|
|
|
|
1. Chatbot communication supports
2. Contact to therapists
3. Self-help tools to cope with conditions
|
1,000,000+
4.8 out of 5.0 (n=72,643)
|
$2.49 to $239.99 (in-app purchase, depend on package)
|
Google App Store – "Mental health."
|
Guided Mental Health Journal - Iona Mind
|
|
|
|
|
|
|
|
|
|
|
|
|
|
Wysa: stress, depression & anxiety therapy chatbot
|
|
|
|
|
|
|
|
|
|
|
|
|
|
Mind journal: anxiety relief & mental health diary
|
Bazimo
CBT
NA
|
Everyone
Health & Fitness
|
|
|
|
|
|
|
|
|
1. Diary
2. Mood tracking
3. Mental health practice
|
100,000+
4.8 out of 5.0 (n=4,873)
|
$12.99 to $32.99 (in-app purchase, depend on package)
|
What's Up? - A Mental Health App
|
Jackson Tempra
CBT and ACT
NA
|
Everyone
Health & Fitness
|
|
|
|
|
|
|
|
|
1. Behaviour tracking (habit)
2. Diary
3. Gamification
4. Mental health practice
5. Mood tracking
6. Daily quotes
|
500,000+
4.8 out of 5.0 (n=3,354)
|
$1.34 to $5.62 (in-app purchase, depend on package)
|
MindDoc: Depression & Anxiety
|
MindDoc Health GmbH
NA
Developed with psychotherapists and scientists
|
Everyone
Medical
|
|
|
|
|
|
|
|
|
1. Information
2. Mental health practice (course)
3. Mood tracking
|
1,000,000+
4.5 out of 5.0 (n=35,355)
|
$8.49 to $129.99 (in-app purchase, depend on package)
|
Google App Store – "Quit smoking"
|
Quit Tracker: Stop Smoking
|
|
|
✓
|
✓
|
✓
|
|
|
|
|
|
|
|
|
Smoke Free, stop smoking now and quit for good
|
|
|
✓
|
✓
|
✓
|
|
✓
|
|
|
Goal setting
|
|
|
|
Stop Smoking - EasyQuit free
|
|
|
✓
|
|
✓
|
|
✓
|
|
✓
|
Quitting plan
|
|
|
|
Flamy - quit smoking & become a non-smoker
|
Offlinefirst
NA
NA
|
Smoker
Health & Fitness
|
|
✓
|
|
|
✓
|
|
|
1. Social support
2. Craving supports
|
|
500,000+
4.8 out of 5.0 (n=10,815)
|
$0.99 to $13.99 (in-app purchase, depend on package)
|
QuitNow!
|
Fewlaps
NA
NA
|
Smoker
Medical
|
✓
|
✓
|
|
|
|
|
|
Quitting plan
|
Mental health practice
|
1,000,000+
4.6 out of 5.0 (n=52,860)
|
$6.99 (in-app purchase)
|
CBT
|
Cognitive Behaviour Therapy
|
DBT
|
Dialectical Behaviour Therapy
|
1
|
Calculator
|
2
|
Calendar
|
3
|
Gamification
|
4
|
Hypnosis
|
5
|
Information
|
6
|
Lung Health Tester
|
7
|
Rationing
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Phase 3: Identifying the top smoking cessation apps for smokers with mental health conditions, smoking cessation apps, and mental health apps available in app stores
Table 5 summarises the details of top listed apps identified from the app store search. The Apple App store search returned twelve apps and the Google App store returned ten apps (some apps exist more than once when searching by different keywords). Three apps (Wysa: Mental Health Support, MindDoc: Depression & Anxiety, and Smoke Free – Stop Smoking Now) existed multiple times in both app stores and for different keywords. Some keywords like "mental health" (n=5), "smok*" (n=7), and "quit" (n=8) are frequently existed in the names of the searched apps.
By entering "mental health smoking" into the Google App store, two of the top five returned apps are focusing on mental health conditions and three are focusing on smoking cessation. The most commonly seen smoking cessation functions are Calculator (n=3) and Gamification (n=3). By entering "mental health" into the same app store, the top five apps are all focusing on supporting mental health management. The most common functions of these apps are Mood tracking (n=4), Mental health practice (n=4), and Diary (n=3). By entering "quit smoking" into the app store, four of the top five returned apps are focusing on supporting users to quit smoking, and one is focusing on both supporting smoking cessation and mental health management. The most common functions among these apps are Calendar (n=4), Gamification (n=3) and information (n=3).
Ten out of twelve identified apps from the Apple App store require in-app purchase, which means some functions of the app are not available to users unless users pay for using. The price of these features ranged from $1.69 to $159.99 NZD (approx. $1.21 to $114.81 USD). All download rates were for apps in the Apple App store. Ten apps have their user rating scores available in the Apple App store. The average user rating score of these ten apps is 4.7 out of 5.0 (ranged from 4.5 to 5.0 out of 5.0). The average number of reviewers is 515 (ranged from 5 to 3100 reviewers).
All apps identified from the Google App store require in-app purchase. The price of these features ranged from NZD $1.69 to $239.99 (approx. $1.21 to $172.22 USD) . Six of these apps were downloaded over 1,000,000 times, two were downloaded over 500,000 times, one was downloaded over 100,000 times and one was downloaded over 1,000 times. The average user rating score of these apps is 4.7 out of 5.0 (ranged from 4.5 to 4.8 out of 5.0). The average number of reviewers is 41,109 (ranged from 94 to 100,413 reviewers).
Phase 4: Identified which apps from the app stores were developed based on theories
All searched apps from the Apple App store (n=12) were developed by individuals or commercial companies. Five out of twelve apps were developed by following theories to help their users. Two of these apps post their development methods in the app store page. All identified apps from the Google App store (n=10) were developed by individuals or companies. Four of them use theory-based approaches to support their users. One shows its development method in the app store page.
Six apps from the Apple App store were developed to target on smokers, five were designed to support the general population who want to maintain good mental health, and one was developed to support construction workers. Eight of these apps are categorised as Health and Fitness apps, three as Lifestyle apps, and one as a Medical app. Five identified apps from the Google App store are targeting on smokers while the other five are targeting on general population. Eight of them are categorised as Health and Fitness apps, and two as Medical apps.
Most apps (n=20 out of 22 apps from both app stores) from app stores have either functions for supporting smoking cessation or managing mental health status. By entering "mental health smoking" into the Apple App store, only two apps were found. One has functions for both smoking cessation and mental health conditions . By entering "mental health" into the Apple App store, the top five returned apps are all focusing on mental health conditions. The most common functions among these apps are Calendar (n=3), Dairy (n=3), and Mood tracking (n=3). By entering "quit smoking" into the Apple App store, the top five returned apps are all focusing on supporting tobacco cessation. From these apps, the most commonly developed functions include Calendar (n=4), Calculator (n=3), and Gamification (n=3).