Unveiling mechanisms of change in digital interventions for depression: Study protocol for a systematic review and individual participant data meta-analysis

Abstract

IntroductionThe efficacy and effectiveness of digital interventions for depression are both well-established. However, precise effect size estimates for mediators transmitting the effects of digital interventions are not available; and integrative insights on the specific mechanisms of change in internet- and mobile-based interventions (IMIs)—as related to key features like delivery type, accompanying support and theoretical foundation—are largely pending.ObjectiveWe will conduct a systematic review and individual participant data meta-analysis (IPD-MA) evaluating the mediators associated with therapeutic change in various IMIs for depression in adults.MethodsWe will use three electronic databases (i.e., Embase, Medline/PubMed, PsycINFO) as well as an already established database of IPD to identify relevant published and unpublished studies. We will include (1) randomized controlled trials that examine (2) mediators of (3) guided and unguided (4) IMIs with (5) various theoretical orientations for (6) adults with (7) clinically relevant symptoms of depression (8) compared to an active or passive control condition (9) with depression symptom severity as primary outcome. Study selection, data extraction, as well as quality and risk of bias (RoB) assessment will be done independently by two reviewers. Corresponding authors of eligible primary studies will be invited to share their IPD for this meta-analytic study. In a 1-stage IPD-MA, mediation analyses (e.g., on potential mediators like self-efficacy, emotion regulation or problem solving) will be performed using a multilevel structural equation modeling approach within a random-effects framework. Indirect effects will be estimated, with multiple imputation for missing data; the overall model fit will be evaluated and statistical heterogeneity will be assessed. Furthermore, we will investigate if indirect effects are moderated by different variables on participant- (e.g., age, sex/gender, symptom severity), study- (e.g., quality, studies evaluating the temporal ordering of changes in mediators and outcomes), and intervention-level (e.g., theoretical foundation, delivery type, guidance).DiscussionThis systematic review and IPD-MA will generate comprehensive information on the differential strength of mediators and associated therapeutic processes in digital interventions for depression. The findings might contribute to the empirically-informed advancement of psychotherapeutic interventions, leading to more effective interventions and improved treatment outcomes in digital mental health. Besides, with our novel approach to mediation analyses with IPD-MA, we might also add to a methodological progression of evidence-synthesis in psychotherapy process research.Study registration with Open Science Framework (OSF)https://osf.io/md7pq/.

Heterogeneity of Treatment Effects in Internet- and Mobile-Based Interventions for Depression

“…Studies at the individual level, such as individual-patient data meta-analyses, could be promising to comprehend these diverse response patterns and their underlying causes . Besides, our understanding of the mechanism of IMI is still limited, which makes it hard to explain why IMIs work . More in-depth studies on the underlying mechanisms of change and effect analysis of specific components are highly needed to understand and optimize IMI for the treatment of depression …”

“…Besides, our understanding of the mechanism of IMI is still limited, which makes it hard to explain why IMIs work . More in-depth studies on the underlying mechanisms of change and effect analysis of specific components are highly needed to understand and optimize IMI for the treatment of depression …”

The Effects of Internet-Based Cognitive Behavioral Therapy for Suicidal Ideation or Behaviors on Depression, Anxiety, and Hopelessness in Individuals With Suicidal Ideation: Systematic Review and Meta-Analysis of Individual Participant Data

“…It is also possible that anxiety and hopelessness may act as effect-mediating variables for suicidal ideation and behaviors in certain individuals. Hence, future studies should adhere to central recommendations for research on change processes [ 61 ] and provide the necessary data to enable mediation analyses in the context of IPDMA [ 62 ].…”

Mediators of digital depression prevention in patients with chronic back pain: Findings from a multicenter randomized clinical trial.

“…Empirically based information on the differential strengths of mediating effects as well as possible interactions between mediators and baseline characteristics (i.e., moderated mediation) might yield important insights for the advancement of psychological interventions and the personalization of depression treatment (Ebert & Cuijpers, 2018; Huibers et al, 2021). At this, novel opportunities in evidence synthesis associated with individual participant data meta-analysis (IPD-MA) might contribute to amend common limitations of process research (Domhardt et al, 2022). Probably the most important advantage over single mediational studies and conventional meta-analyses of aggregated data is the increase in statistical power, since IPD-MA combine the data from relevant trials on the individual participant level.…”

“…Probably the most important advantage over single mediational studies and conventional meta-analyses of aggregated data is the increase in statistical power, since IPD-MA combine the data from relevant trials on the individual participant level. Furthermore, IPD-MA allow for the consistent harmonization of variables (e.g., mediator and outcome instruments; measurement points) and standardization of imputation strategies across studies (Büscher et al, 2020(Büscher et al, , 2022Domhardt et al, 2022;Lin et al, 2019). Overall, IPD-MA facilitate advanced statistical approaches for mediation analysis and might enable integrative and original findings on change mechanisms in psychological interventions for depression in the future.…”