Treating depression with a smartphone-delivered self-help cognitive behavioral therapy for insomnia: study protocol for a parallel group randomized controlled trial

This is a two-arm, with equal randomization (1:1 allocation ratio) parallel, superiority RCT. It compares a self-help smartphone-based CBT-I intervention to a waitlist control condition. The self-help treatment is delivered through “proACT-S,” a smartphone application developed by the corresponding author’s research team. The results from a pilot study showed that proACT-S was efficacious for treating insomnia and was positively received by the users [23]. The current RCT is designed to test the efficacy of proACT-S in treating people with MDD and insomnia. Participants’ change in depressive and insomnia symptoms after the CBT-I intervention will be compared with that of the waitlist control group. The rationale for choosing waitlist control as the comparison condition is twofold: (1) it allows researchers to determine the effect of the intervention against not receiving treatment during the trial period and (2) it ensures that all participants will eventually receive the treatment.

Prior to trial entry, participants complete a two-stage screening. Their eligibility is assessed by an online survey, followed by a telephone diagnostic interview. After the two-stage screening, the assessments, randomization, and intervention are carried out via proACT-S. The research design is summarized in Fig. 1. The full SPIRIT checklist is provided as Additional file 1.

This RCT is conducted in Hong Kong, where the 12-month prevalence of MDD among adults was estimated at 8.4% [1], and the weighted prevalence of insomnia among adults was 39.4% [25].

A two-stage screening is set up to ascertain whether or not participants fulfill the eligibility criteria. Stage 1 is an online rapid screening and is conducted in the Chinese language. Participants are screened for the aforementioned inclusion criteria 1 to 9, as well as for the aforementioned exclusion criteria 1 to 6. Demographic information is collected, including Hong Kong residency, age, predominant sleep complaints, and the extent of the resulting distress or impairment in social, occupational, and other important areas of functioning. Participants are asked if they are able to read Chinese and type Chinese or English, have a smartphone device (iOS or Android operating system) with Internet access, and have a regular email address. Participants’ severity of insomnia symptoms is measured by the Insomnia Severity Index [29], and each item is rated on a 4-point Likert scale, ranging from “not at all” to “extremely.” It has been validated in Hong Kong samples [30, 31] and has high internal consistency (Cronbach’s alpha = .81 [31]). Participants’ severity of depressive symptoms is measured by the PHQ-9, and each item is rated on a 4-point Likert scale, ranging from “not at all” to “nearly every day.” It has been validated in Hong Kong samples [32] and has high internal consistency (Cronbach’s alpha = .82 [32]). Participants’ suicidal ideation is assessed by BDI-II item 9. Participants are asked to indicate whether they are receiving any concurrent psychological treatment at least once per month, whether they had participated in the proACT-S pilot clinical trial, whether they are currently taking prescribed psychiatric medication regularly, whether they are diagnosed with psychosis or schizophrenia, and whether they are participating in any other academic studies or clinical trials related to insomnia and/or depression.

Stage 2 is a telephone diagnostic interview screening and is conducted in Cantonese. It is used to assess clinical depression and insomnia, which correspond to inclusion criteria 10 and 11. The clinical insomnia inclusion criterion is developed with reference to the Diagnostic and Statistical Manual of Mental Disorders—Fifth Edition (DSM-5 [33]) insomnia disorder diagnostic features. Difficulty initiating sleep is defined by a subjective sleep latency greater than 30 min, difficulty maintaining sleep is defined by frequent awakenings or problems returning to sleep within 30 min after awakenings, and early morning awakening is defined by awakening at least 30 min before the scheduled time and the total sleep time before the awakening is less than 6.5 h. The clinical depression inclusion criterion is based on the modified Chinese version of the Revised Clinical Interview Schedule (CIS-R [34]) algorithm for ICD-10 Mild depressive episode without somatic symptoms (F32.00). The timeframe for items measuring ICD-10 depressive episode has changed from “in the past week” to “in the past 2 weeks” to tap the 2-week requirement for DSM-5 depressive episode diagnostic criteria. In order to meet the criteria of mild depressive episode without somatic symptoms, the participants need to fulfill the following four conditions: (1) having a minimum of 2-week duration of depressive episode; (2) endorsing at least two prominent symptoms of depression—depressed mood, loss of interest, fatigue—in the past 2 weeks; (3) endorsing at least two of the other common depressive symptoms—reduced concentration, reduced self-esteem, ideas of guilt or worthlessness, pessimism about future, suicidal ideation, disturbed sleep, change in appetite with corresponding weight change—in the past 2 weeks; and (4) obtaining a norm-based mental component score of ≤ 45 in the 12-item Short-Form Health Survey Version 1 (SF-12 Version 1) [35]. Because no epidemiological research has been conducted to assess the screening utility of the SF-12 Version 1 mental health component scale for diagnosable depression in Hong Kong Chinese population, the cutoff score of ≤ 45 was chosen with reference to a study that assessed its diagnostic accuracy to predict depression in the general Australian population [36]. In addition, stage 2 telephone diagnostic interview screening is used to reject participants who meet the aforementioned exclusion criteria 2 to 7.

The self-help CBT-I treatment content is based on the Chinese translated version of a well-established CBT-I treatment manual entitled “Insomnia: A Clinician’s Guide to Assessment and Treatment” [37]. CBT-I aims at changing dysfunctional cognitive beliefs and maladaptive behaviors that contribute to the maintenance of insomnia. The self-help CBT-I treatment is delivered in the Chinese language in six consecutive weekly modules via proACT-S. The duration of each module is around 45 to 60 min. The content of each treatment module is displayed in Table 1.

proACT-S has been pilot tested in a sample of 32 Hong Kong Chinese participants and, later, revamped to improve user experience. One current recommendation for engaging app users was to reduce the amount of text and, instead, to use videos to deliver treatment content [38]. Therefore, animations were added to the text-based materials to enhance user experience. Following the literature recommendations [39, 40], more interactive components were incorporated into the app. In particular, proACT-S now provides (a) a clear timeline to indicate the start date for each assessment and treatment module, (b) indicators for module and assessment completion, (c) more prompts for users to follow in completing the weekly homework, (d) a modifiable sleep diary that accommodates the sleep pattern of shift-workers, and (e) individualized homework feedback.

Reasons for discontinuation of CBT-I may include, but are not limited to, the following: (1) participants’ decision to discontinue treatment at any time for any reason and (2) principal investigator’s decision to terminate treatment for the participants’ safety reasons at any time.

Individuals interested in participating are invited to complete a two-stage screening. In stage 1 online rapid screening, they complete an online survey to review their eligibility. Those who have passed the online rapid screening will receive a link within the Qualtrics platform to sign up for the stage 2 telephone diagnostic interview screening. These telephone interviews are conducted by project assistants, who have been trained and supervised on the administration of the modified Chinese version of the CIS-R [34].

Individuals who do not meet the stage 2 telephone diagnostic interview screening eligibility criteria will receive a list of references related to insomnia and depression produced by the Department of Health and the Social Welfare Department under the Government of the Hong Kong SAR. Information regarding crisis hotlines and integrated community centers for mental wellness are provided to those currently with suicidal plans or acts, or those who have had suicidal plans or acts within the past 12 months.

Individuals who have passed the two-stage screening are directed to download proACT-S either from App Store or Google Play. Eligible participants are guided to register for their own personal accounts to enter the main study trial. They then complete the baseline assessment via proACT-S. After that, they are randomly assigned in a 1:1 ratio either to CBT-I condition or waitlist control condition.

Participants in the CBT-I condition start the 6-week CBT-I immediately after randomization, complete the post-intervention assessment right after they finish the treatment, and complete the follow-up assessment 6 weeks after the post-intervention assessment. Participants in the waitlist control group wait for 6 weeks without the proACT-S intervention and then complete the post-intervention assessment 6 weeks after the baseline assessment. The waitlist control participants start CBT-I (equivalent to that of the CBT-I group) immediately after completing the post-intervention assessment, and they complete the follow-up assessment right after finishing the 6-week CBT-I.

Emails and WhatsApp reminders are sent to participants to increase their engagement and to enhance treatment compliance. Upon completion of the study, each eligible participant receive cash coupons of HKD $100 as a token of appreciation for their participation. The proposed flow of participants is displayed in Fig. 2.

The most updated meta-analysis of 28 self-help CBT-I RCTs [19] showed a significant treatment effect in alleviating depressive symptoms (Hedges’ g = 0.35) and insomnia symptoms (Hedges’ g = 0.79). It also found that the mean cumulative study attrition rates were 21.25% (SD = 15.31%) and 18.4% (SD = 18.21%) in the treatment and the waiting list/routine care/no treatment/psychoeducation groups, respectively. Hence, a conservative small effect size (Cohen’s f = 0.2) and an attrition rate of 30% are estimated for the present study.

The sample size calculation for each of the three primary outcomes (i.e., insomnia severity, poor sleep quality, and depression severity) is based on mixed ANCOVA using GPower 3.1. To conduct a 2 (condition: CBT-I versus waitlist control) × 2 (assessment: baseline versus post-intervention) mixed ANCOVA with an alpha value set at 0.05, two-sided, 80% power to detect a small effect of 0.2 (Cohen’s f) between two groups while controlling for 12 covariates (demographics, clinical comorbidity, treatment expectancy, and acceptability of treatment), a total sample size of 199 will be required. In order to account for 30% attrition, a total sample of 285 participants will be sufficient to detect a small effect size (Cohen’s f = 0.2) for the difference in the change in each of the three primary outcomes (i.e., insomnia severity, poor sleep quality, and depression severity) from baseline to post-intervention between CBT-I condition and waitlist control condition with a two-sided 5% significance level and a power of 80%.

Participants are recruited on a rolling basis through posters, web-based advertisements, departmental website, social media, and institutional mass mailing. A “proACT-S” Facebook page and a “proACT-S” Instagram account have also been set up for this project, where they contain the recruitment poster and local news articles related to insomnia and depression. Recruitment began in March 2019 and was completed in September 2020.

One week following the completion of the baseline assessment, participants are randomly assigned in a ratio of 1:1 either to the CBT-I group or the waitlist control group using an online randomized algorithm (https://www.php.net/manual/en/function.random-int.php↗). The group assignment follows the simple randomization procedure and is completely automated to ensure allocation concealment.

The principal investigator is blind to both the outcome assessment and group assignment. The research team is blind to the outcome assessment because all three assessments are self-reported and carried out via the smartphone app, but is not blind to the group assignment as research members need to send emails and WhatsApp reminders to the participants to enhance treatment compliance. Efforts are made to minimize participants’ knowledge of treatment allocation by informing participants that the treatment start date is randomly assigned. Statistical analyses will be carried out by a researcher blind to the study protocol. In the unlikely event of a critical incident, the research team, as well as the principal investigator, will be authorized to break the blind and carefully record it on the Case Report Form.

Psychiatric staff who were involved in validating the Chinese version of the CIS-R in Hong Kong were consulted regarding the telephone diagnostic interview training, item selection, and ICD-10 scoring algorithm. Clinical psychologists specialized in sleep disorders and potential end-users were invited by the research team to provide feedback regarding the study design (e.g., the measures, recruitment strategies, Facebook page), as well as proACT-S revamp and beta testing.

Adverse events, such as increased suicidal risk and hospital admission, study attrition rates, and significant deterioration in primary outcomes, are monitored and recorded throughout the study trial. Treatment discontinuation decision may be made at the discretion of the principal investigator, for reasons concerning participants’ safety. The proportion of participants experiencing any adverse events in each group will be reported in the results of this RCT study.

The principle of intention-to-treat analysis will be adopted, in which all randomized participants with missing observations, from lost to follow-up or incomplete outcome assessments, will be handled by multiple imputation [53]. Missing data is assumed to be 5%.

Chi-square tests and independent t tests will be conducted to examine if participants in the CBT-I and waitlist control conditions differ in terms of demographic characteristics, clinical comorbidity, and baseline outcome scores. Multilevel linear mixed model based on the intention-to-treat principle will be used to calculate between-condition mean differences in the primary outcome changes in sleep quality, insomnia, and depression severity from baseline to post-intervention assessments. Multilevel linear mixed model based on the intention-to-treat principle will also be used to analyze secondary outcomes of the baseline to post-intervention change in subjective health and anxiety between CBT-I and waitlist control conditions. Clustering effect, significant baseline differences in demographics, clinical characteristics, and outcome variables will be adjusted for. Pair-sample t tests based on the intention-to-treat principle will be used to analyze changes in primary outcomes, subjective health, and anxiety obtained at post-intervention and 6-week follow-up separately for each condition. All comparisons are planned with a 5% two-sided significance level. Bonferroni adjustment will be applied.

Consent is obtained electronically for the stage 1 online rapid screening, verbally for the stage 2 telephone diagnostic interview screening, and via the smartphone app proACT-S for the 6-week CBT-I intervention. The consent form explains that participation is voluntary; individuals could withdraw from the study at any time without any consequences.

Participants directly enter their data via Qualtrics during the stage 1 online rapid screening and via proACT-S during the main trial study. Manual data entry from trained project assistants (i.e., telephone interviewers) is required for recording participants’ stage 2 telephone diagnostic interview screening data. A Qualtrics survey based on the modified Chinese version of the CIS-R [34] was created to enable data entry, coding, and storage, in addition to standardizing the administration of the stage 2 screening across different trained telephone interviewers. Participants’ personal data are sent to the electronic server located at The University of Hong Kong and protected using dual encryption. The principal investigator and the research team are given access to the dataset. Participants’ research files may be reviewed by the Human Research Ethics Committee of the University of Hong Kong in order to check that the study is being carried out correctly. Participants will not be identified by name in any report of the completed study. Their personal data will be kept for five years after the publication of the first original research paper, and research data without personal identifiers will be stored for long term retention at the Community Action Research Laboratory at The University of Hong Kong.

This protocol will be published in an open-access journal for public access. Researchers interested in using the de-identified dataset to test novel hypotheses could contact the corresponding author and submit a data proposal form to be reviewed by the research team. The study findings will be disseminated in peer-reviewed publications and conference presentations. Executive summaries will be made available on the proACT-S project website and disseminated to other organizations such as the funding agency and local news agencies.

Not applicable.