Efficacy of self-guided internet-based cognitive behavioral therapy in the treatment of depressive symptoms a meta-analysis of individual participant data
Summary (4 min read)
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- Any studies [1] [2] [3] [4] have found that depressive symptoms can be effectively treated with psychotherapy, pharmacotherapy, or both.
- Nevertheless, many people with depressive symptoms do not seek help, and even well-resourced health care systems find it difficult to marshal enough qualified therapists to offer psychological interventions.
- 14, 15 These contradicting findings drew much attention and raised concerns about the benefits of these interventions.
- 16 Meta-analyses using individual participant data (IPD) estimate aggregate effect sizes using IPD from RCTs.
- The term self-guided iCBT is defined as CBT delivered via the internet, which may involve automated feedback but does not provide support related to the therapeutic content.
Eligibility Criteria
- Studies were included if the participants were adults (aged >18 years) with elevated symptoms of depression based on any diagnosis or any self-report scale of depression.
- Only those RCTs in which self-guided iCBT was compared with a control condition (usual care, waiting list, or attention control) were included.
- No language or publication status exclusions were applied.
Study Identification and Selection Process
- The analysis was completed in compliance with the Preferred Reporting Items for Systematic Review and Metaanalyses IPD Statement.
- The authors used an existing database on psychological treatments for depression 18 that is updated annually by a systematic literature search in the bibliographic databases of PubMed, Embase, PsycINFO, and Cochrane Library (from inception to January 1, 2016).
- Two researchers (P.C. and E.K.) independently examined titles and abstracts of 13 384 articles.
- In case of disagreement regarding inclusion, consensus was sought through discussion.
- The authors also asked key researchers in the field whether they knew of unpublished trials.
Data Collection and Data Items
- Authors of eligible articles were contacted for permission to use their data sets.
- Reminders were sent after 2 weeks and if necessary after 1 month.
- Finally, the authors combined all individual data sets into a merged data set, using a generic standardized protocol for integrating IPD sets.
- The authors also used study-level variables, which were available from the full reports (type of comparator condition, recruitment, level of support).
- The selection of moderator variables has been based on previous literature related to moderators of face-to-face CBT or iCBT.
Risk of Bias Assessment in Individual Studies
- The authors examined the risk of bias in the included studies using the criteria of the Cochrane Collaboration risk of bias assessment tool.
- 20 Two independent reviewers (E.K., P.C.) evaluated the included studies to determine whether there was a risk for bias related to selection, performance, detection, attrition, and outcome reporting.
- In case of unclear risk of bias for 1 or more key domains, the authors contacted the first authors of the included studies for clarifications.
Key Points
- Internet-based cognitive behavioral therapy was more effective compared with controls.
- Adherence predicted better treatment outcomes within the experimental condition.
- Meaning Self-guided internet-based cognitive behavioral therapy may be a viable alternative to current first-step treatment approaches for symptoms of depression, particularly in those individuals who are not willing to have any therapeutic contact.
IPD Meta-analysis
- Studies included in this IPD meta-analysis used measures such as the Center of Epidemiologic Studies-Depression Scale, 22 the Beck Depression Inventory I 23 or II, 24 (hereafter referred to as Beck Depression Inventory) or the 9-item Patient Health Questionnaire 25 to monitor change in depressive symptoms severity.
- The authors also conducted sensitivity analyses using only participants with complete data after treatment to examine whether there was a difference between those who dropped out of the RCTs and those who provided posttreatment data.
- 27, 28 We calculated the standardized β coefficient for the examined comparisons.the authors.the authors.
- Second, the authors analyzed the effects of the interventions on treatment response (defined as a 50% reduction in baseline depressive symptoms scores) at the posttreatment assessment using a multilevel mixed-effects logistic regression (using a random intercepts model with a random effect for each trial and fixed effects for the intervention and the depressive symptoms severity, using STATA's melogit command).
- Two-stage IPD meta-analysis facilitates analysis standardization across the included studies and estimation of outcomes that are not available in the published reports, such as treatment response.
Exploration of Variation in Effects: Participant-Level Moderators
- The authors tested whether available demographic and clinical characteristics moderated the effect of self-guided iCBT on depression outcomes (depressive symptoms severity and treatment response).
- Not all included studies reported data on the examined moderators (for precise numbers regarding the missing data, see Table 1 and Table 2 ).
- To examine moderators, the authors added the interaction between each potential moderator and treatment outcome on depression severity into the multilevel mixed-effects linear regression model.
- The authors similarly added the interaction between each potential moderator and treatment response into the multilevel mixed-effects logistic regression model.
Treatment Adherence as a Predictor Within the Treatment Group
- The authors examined whether adherence to treatment predicted within treatment group effect size for the experimental condition only, using a linear mixed model, which regressed posttreatment depressive symptoms severity on treatment adherence and baseline depressive symptoms severity (fixed effects) and using random intercepts for the studies.
- Treatment adherence was defined as the total number of sessions that each participant completed divided by the total number of treatment sessions.
Study and Participant Characteristics
- The included studies were conducted in 6 countries: Australia, Germany, Spain, Switzerland, the Neth-erlands, and the United Kingdom (eTable 1 in the Supplement presents a summary of study characteristics).
- The mean baseline depressive symptoms scores were 25.7 on the Center of Epidemiologic Studies-Depression Scale, 28.3 on the Beck Depression Inventory, and 14.1 on the 9-item Patient Health Questionnaire in their respective studies.
- (eTable 2 in the Supplement provides a summary of participants' characteristics.) .17 a This is a sensitivity analysis that was conducted including only participants who completed posttreatment depression questionnaires.
Results of Traditional Meta-analysis
- Sixteen studies examined the comparison between selfguided iCBT and control groups.
- There was no significant difference between the outcome findings of studies included in the present IPD meta-analysis and studies with unavailable data (P = .95) .
- There was some indication of publication bias.
One-Stage IPD Meta-analysis: Depressive Symptoms Severity
- Table 1 presents the main findings of the 1-stage IPD metaanalysis on depressive symptoms severity after testing (ranging from 6 to 16 weeks after randomization).
- None of the participant-level variables (sociodemographic and clinical characteristics) significantly moderated outcome after treatment (Table 1 ).
- Adherence to treatment predicted significantly better outcomes within the self-guided iCBT group (β = −0.19; P = .001).
Discussion
- The authors examined the effects of self-guided iCBT on severity and treatment response.
- The authors found that self-guided iCBT had lower depressive symptom severity and greater treatment response compared with control conditions after testing.
- These findings were robust in complete case analyses.
- None of the examined participant-and study-level variables significantly moderated the treatment effect.
- The role of treatment adherence in outcomes has been identified by a previous review in the field conducted by Donkin and colleagues.
Strengths and Limitations
- Among the strengths of the present study was its high power to detect small statistically significant differences between intervention and controls and to yield more precise and robust evidence compared with traditional meta-analyses.
- Moreover, the included RCTs had high methodologic quality, which allows us to be confident that the present analysis is relatively free of critical biases.
- This repeated administration of symptom inventories might yield lower mean scores with each wave of measurement (completer biases related to self-report ratings).
- 45 Moreover, the included studies did not report on recruitment issues related to large-scale, fully unguided internetadministered interventions, including factors such as repeated registration attempts by individuals who did not meet inclusion criteria or who were dissatisfied with their intervention allocation.
Conclusions
- Self-guided iCBT produces results that are encouraging.
- The absence of a significant difference in treatment outcomes associated with clinical and sociodemographic characteristics implies that self-guided iCBT can be used by most individuals with depressive symptoms regardless of the severity of their symptoms or their sociodemographic background.
- Currently, antidepressant medications are widely used in the treatment of depressive symptoms, whereas psychotherapeutic interventions are provided to a lesser degree, despite many individuals with depressive symptoms preferring psychotherapy to antidepressants.
- 46 However, the high treatment costs and the limited number of trained clinicians hamper the implementation of psychotherapy in practice.
- Unguided iCBT has several limitations that should be addressed before it is disseminated as part of routine care (eg, high dropout rates, small effects compared with face-to-face and guided internet interventions, and possible participant selection bias).
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Frequently Asked Questions (5)
Q2. What is the advantage of using two-stage IPD meta-analysis?
Two-stage IPD meta-analysis facilitates analysis standardization across the included studies and estimation of outcomes that are not available in the published reports, such as treatment response.
Q3. What measures were used to monitor change in depressive symptoms severity?
Studies included in this IPD meta-analysis used measures such as the Center of Epidemiologic Studies–Depression Scale,22 the Beck Depression Inventory I23 or II,24 (hereafter referred to as Beck Depression Inventory) or the 9-item Patient Health Questionnaire25 to monitor change in depressive symptoms severity.
Q4. How many people need to be treated with self-guided iCBT?
The current findings indicate that the authors need to treat 8 individuals with depressive symptoms with self-guided iCBT to expect a 50% symptom reduction.
Q5. What limitations should be addressed before iCBT is disseminated?
Although it is beyond the scope of this study, unguided iCBT has several limitations that should be addressed before it is disseminated as part of routine care (eg, high dropout rates, small effects compared with face-to-face and guided internet interventions, and possible participant selection bias).