Different control conditions can produce different effect estimates in psychotherapy trials for depression.

Area of Science:

• Psychiatry and Mental Health
• Clinical Psychology
• Evidence-Based Medicine

Background:

• The influence of control conditions on the efficacy of psychotherapeutic interventions for depression remains unclear.
• Accurate estimation of treatment effects is crucial for clinical decision-making and guideline development.

Purpose of the Study:

• To investigate how different control conditions affect effect size estimates in psychotherapy trials for depression.
• To compare the relative strength of various control groups, including Waiting List (WL), No Treatment (NT), Pill Placebo (PillPlacebo), and Psychological Placebo (PsycholPlacebo).

Main Methods:

• A comprehensive literature search was conducted across four major databases (PubMed, PsycINFO, Embase, Cochrane) for randomized trials of psychotherapies for adult depression up to January 1, 2019.
• Network meta-analysis was employed to compare broadly conceived cognitive behavior therapies against different control conditions.
• 123 studies involving 12,596 participants were included in the analysis.

Main Results:

• Heterogeneity was moderate (I-squared = 55.9%), with no significant inconsistency detected in the network meta-analysis (P = 0.44).
• Different control conditions yielded varying estimates of intervention efficacy.
• Waiting List (WL) emerged as the weakest control group, showing higher odds ratios for response compared to No Treatment (NT), Psychological Placebo (PsycholPlacebo), and Pill Placebo (PillPlacebo).

Conclusions:

• The selection of control conditions significantly influences effect estimates in randomized controlled trials of psychotherapy for depression.
• A hierarchy of control group strength was identified: WL < NT < PsycholPlacebo < PillPlacebo.
• Future meta-analyses should avoid pooling diverse control conditions to ensure accurate and reliable efficacy estimates for psychotherapies.