This registered pilot interventional trial (NCT05523492; https://beta.clinicaltrials.gov/study/NCT05523492) used a single-group pre- to post-treatment design. Prospective participants learned about the Online Therapy Unit (www.onlinetherapyuser.ca) through a variety of sources, such as family physicians, other medical professionals, community mental health clinics, web-based searches, word of mouth, media, and posters or cards. To access the course, participants completed an online questionnaire followed by a telephone interview. During this interview, staff determined if participants met basic eligibility for the Course (i.e., ≥18 years of age, Saskatchewan resident, endorsed depression and/or anxiety symptoms, had access to a computer and the Internet, able to provide a healthcare provider emergency contact), or were experiencing concerns outside of the scope of the Course (i.e., are at a high risk for suicide, have significant alcohol and/or drug usage, or are experiencing unmanaged psychosis or mania). One additional inclusion criterion specific to this study was that patients had to self-identify as belonging to PDEGs. Participants who did not meet the eligibility criteria were directed to more appropriate local services (see 4for further details). All eligible PDEG participants (N=41) enrolled in ICBT at the Online Therapy Unit between June 2022 and November 2022 were included (see Figure 1 ). Sub-sample (e.g., self-identified non-White/Caucasian) data (N=134) collected between December 2021 and May 2022 at the same site with an equivalent protocol were used as the benchmarking sample [see (15) for details about benchmarking sample].

At post-treatment ~32% (n=13) consenting participants in the pilot study were interviewed asking about their expectations and experience with the adapted ICBT Wellbeing Course and suggestions for further improvement.

Participants were enrolled in the Adapted Wellbeing Course. This transdiagnostic course originally developed by Titov, Dear (16) addresses both depression and anxiety symptoms and was adapted as described above for PDEGs. The Course includes five online psychoeducational lessons and described (a) the cognitive-behavioural model and the relationship between thoughts, behaviours and emotions; (b) thought monitoring and challenging; (c) de-arousal strategies and pleasant activity planning; (d) graded exposure and behavioural activation; and (e) relapse prevention. This course is completed over ~ 8 weeks and complemented with once-weekly therapist emails or telephone calls where therapists answer patients’ ‘ questions about the course and provide guidance on use of skills. Each lesson includes a brief video, educational materials, case stories, homework suggestions (i.e., do-it-yourself guides) and frequently asked questions along with additional reading if patients are interested. Weekly automated email reminders are sent to remind patients’ of the Course [see (16) for details].

Data were self-reported. Demographic variables (e.g., age, sex, ethnicity, education, marital status, employment status, etc.) were recorded at pre-treatment. Considering vast diversity in ethnocultural backgrounds of patients in the Canadian context (17), ethnicity was assessed using broadly used ethno-racial categories, that is, black, white, Asian (east, middle east, south), Indigenous (First Nations, Inuit, Métis), Latin American, and other (with the option for participants to describe their ethnicity).

Consistent with past research (4, 18), ICBT engagement was assessed using number of patient messages, phone calls, and lessons accessed. Following previous research, for treatment satisfaction, at post-treatment, participants answered yes/no items about whether they would recommend the treatment to a friend, and if the course was worth their time. Participants also rated satisfaction with the program, materials, and confidence to manage symptoms, and motivation to seek future treatment if needed (1 to 5 scale). Patients completed measures of depression [Patient Health Questionnaire-9 [PHQ-9]; (19)] and anxiety [Generalized Anxiety Disorder-7 [GAD-7]; (20)] at pre-treatment (baseline), each week for seven weeks, and post-treatment (end of week 8). Scores ≥10 in these measures indicate clinically significant symptoms of depression or generalized anxiety. Cronbach’s α in this study was between.66 and.91, and.81 and.93 for PHQ-9 and GAD-7, respectively.

The post-treatment qualitative interviews included 12 open-ended questions that asked about the patient’s experience with the program, including perceived cultural relevance of different aspects of the ICBT program, and ways to improve accessibility and utilization of the program for PDEGs [see (12) for details].

Statistical analyses were conducted using IBM SPSS Statistics (Version 28.0). Descriptive statistics described patients’ characteristics. Pilot versus benchmark groups were compared on pre-treatment characteristics, engagement and satisfaction measures using Chi square tests for categorical variables and t-tests for continuous variables. A series of mixed model analyses were run using all data available across the nine weekly assessments to examine changes in the PHQ-9 and GAD-7 outcomes over time and to determine if these changes differed between groups. For each outcome, a series of models involving fixed and random effects of intercept and slope (time) were conducted. The fixed-effect models included time, group, and their interaction (time × group). Intraclass correlation coefficients were used to determine if mixed-model analyses were appropriate (21). Various within-individual covariance structures (e.g., scaled identity, diagonal, autoregressive [AR (1)]) were also tested. The models with smallest Akaike’s Information Criterion and Bayesian Information Criterion were selected for the final analysis. Estimates were calculated using the full information maximum likelihood method. These analyses were conducted twice, 1) using an intention-to-treat (ITT) sample, for which data were imputed using the Multiple Imputation method such that all enrolled participants were included, and 2) using a complete case analysis, for which unimputed data were used. For the ITT analyses, twenty multiply imputed data sets were created (22). Since mixed-model analysis with maximum likelihood method of estimation can handle missing data, imputation prior to analysis was not necessary for complete case analysis (23, 24). Pre- to post-treatment effect sizes (Cohen’s d) were computed using estimated means and standard deviations from the mixed model analysis. Further, we compared the groups on reliable change by calculating the percentage of participants who recovered (GAD-7 or PHQ-9 ≤ 4), improved reliably (GAD-7 or PHQ-9 ≤ 9), or did not show reliable improvement (GAD-7 or PHQ-9 ≥ 10). Pre-treatment standard deviations and test-retest reliability estimates α = .84 for PHQ-9 (19) and α = .83 for GAD-7 (20) were used to compute reliable change index (25).

The digitally recorded post-treatment qualitative interviews were transcribed verbatim, coded by combining deductive and inductive approaches, and organised according to themes for thematic analysis (26). The frequency of each code was recorded for descriptive analysis. The semi-structured interview data were coded by a researcher (EV) using NVivo (version 12 Plus) software.

There were no significant differences in attrition between pilot (41.5%) and benchmark (41.0%) groups on post-treatment outcome variables (p = .55) or mean number of lessons completed (pilot: 3.78 (SD = 1.79) vs benchmark: 3.99 (SD = 1.74), p = .47). Also, the groups did not significantly differ on the mean number of messages and phone calls to therapists (see Table 2 ).

Although slightly higher percentage of pilot study participants reported satisfaction in most of the variables, there was no statistically significant differences between pilot and benchmark groups on satisfaction variables (see Table 2 ).

As expected, ITT analysis yielded a non-significant interaction effect for the PHQ-9 (β ₁ = − 0.01, 95% CI = [− 0.28, 0.21], p = .943) and the GAD-7 (β ₁ = − 0.13, 95% CI = [− 0.35, 0.09], p = .261). Similar results were obtained for the complete case analysis of the PHQ-9 (β ₁ = − 0.03, 95% CI = [− 0.29, 0.34], p = .866) and GAD-7 (β ₁ = -0.09, 95% CI = [− 0.41, 0.22], p = .553), suggesting that the change in self-reported depression and generalized anxiety symptoms over 9 weeks was not significantly different between groups (see Figure 2 ). For both groups, significant reductions on the PHQ-9 (β ₁ = − 0.82, 95% CI = [− 1.01, − 0.64], p < .001) and GAD-7 (β ₁ = − 0.79, 95% CI = [− 0.94, − 0.65], p < .001) were observed over time in ITT analyses as well as in the complete case analyses, PHQ-9 (β ₁ = − 0.91, 95% CI = [− 1.06, − 0.57], p < .001) and GAD-7 (β ₁ = − 0.80, 95% CI = [− 0.95, − 0.64], p < .001). Final models used AR (1) within-individual covariance structure. Similar large pre-to-post within-group effect sizes (Cohen’s d) were found for the PHQ-9 in the pilot (d = 1.23, 95% CI [0.68, 1.77]) and benchmark (d = 1.18, 95% CI [0.88, 1.48]) groups and for the GAD-7 pilot (d = 1.24, 95% CI [0.69, 1.79]) and benchmark (d = 1.27, 95% CI [0.97, 1.58]) groups.

On the PHQ-9 at post-treatment, for the pilot group (n=24), 10 (41.7%), 4 (16.7%), and 10 (41.7%) met criteria for recovered, reliable improvement, and did not improve reliably, respectively. In the benchmark group (n=79), 27 (34.2%), 19 (24.1%), and 33 (41.8%), met criteria for recovered, reliable improvement, and did not improve reliably, respectively, on the PHQ-9. Similarly, on the GAD-7, in the pilot group (n=24), 8 (33.3%), 6 (25.0%), and 10 (41.7%) met criteria for recovered, reliable improvement, and did not improve reliably, respectively. In the benchmark group (n=79), 28 (35.4%), 20 (25.3%), and 31 (39.2%) met criteria for recovered, reliable improvement, and did not improve reliably, respectively.

One (2.4%) pilot study participant and 11 (8.2%) benchmark study participants self-reported negative effects during the treatment period. In both groups, negative effects were related to transient increases in symptoms during ICBT, such as, when confronting bad memories, when challenging thoughts, or thinking about symptoms.

Thirteen self-identified PDEG participants representing Indigenous (53.8%), Asian (23.1%) and Black (23.1%) communities were interviewed. There were equal number of self-identified men and women (n=6, 46.2% each) and one (7.7%) transgender participants, with an average age of 31 years (SD = 11.4 years).

A majority of the interview participants (n=12, 92.3%) indicated that the ICBT program met or exceeded their expectations and reported having positive experiences with the therapists. Likewise, in terms of cultural fit of the ICBT program, a majority (n=10, 76.9%) said that the program aligns with their cultural beliefs and practices. When asked for suggestions for specific improvements to make the program better for people from their ethnocultural background, seven (53.8%) participants mentioned that there was no need for change in the program. The remaining (n=6, 46.2%) participants provided some suggestions for further improvements: making the public more aware about this freely available program (n=2, 15.4%), adding culture-specific content (n=2, 15.4%), diversifying the cultural background of the main characters represented in the case stories (n=2, 15.4%), language translation (n=1, 7.7%), and increasing therapist support (n=1, 7.7%).