Predictors, Moderators, and Mediators Associated With Treatment Outcome in Randomized Clinical Trials Among Adolescents With Depression: A Scoping Review

Importance

The application of precision medicine principles for the treatment of depressive disorders in adolescents requires an examination of the variables associated with depression outcomes in randomized clinical trials (RCTs).

Objective

To describe predictors, moderators, and mediators associated with outcomes in RCTs for the treatment of depressive disorders in adolescents.

Evidence Review

A scoping review of RCTs for the treatment of depression in adolescents was conducted. Databases searched included MEDLINE, Embase, APA PsycInfo, and CINAHL. Included publications tested predictors, moderators, and/or mediators associated with depression symptom outcomes (eg, symptom reduction, response, remission) in RCTs pertaining to the treatment of adolescents, ages 13 to 17 years. Predictors were defined as variables that were associated with depression outcomes, independent of treatment group. Moderators were defined as baseline variables that were associated with differential outcomes between treatment groups. Mediators were defined by a formal mediation analysis. In duplicate, variables were extracted and coded with respect to analysis type (univariable or multivariable), statistical significance, direction of effect size, reporting of a priori hypotheses, and adjustment for multiple comparisons. Aggregated results were summarized by variable domain and RCT sample.

Findings

Eighty-one articles reporting on variables associated with outcomes across 33 RCTs were identified, including studies of biological (10 RCTs), psychosocial (18 RCTs), and combined (4 RCTs) treatments as well as a service delivery model (1 RCT). Fifty-three variable domains were tested as baseline predictors of depression outcome, 41 as moderators, 19 as postbaseline predictors, and 5 as mediators. Variable domains that were reported as significant in at least 3 RCTs included age, sex/gender, baseline depression severity, early response to treatment, sleep changes, parent-child conflict, overall psychopathology, suicidal ideation, hopelessness, functional impairment, attendance at therapy sessions, and history of trauma. Two publications reported a priori hypotheses and adjustment for multiple comparisons, both finding that baseline depression severity and family conflict were associated with poorer outcomes.

Conclusions and Relevance

This review identified commonly researched variables requiring more scrutiny as well as underresearched variables to inform future study designs. Further efforts to discover predictors, moderators, and mediators associated with treatment response have great potential to optimize care for adolescents with depression.

Forks in the road: Definitions of response, remission, recovery, and other dichotomized outcomes in randomized controlled trials for adolescent depression. A scoping review

BACKGROUND

Definitions of dichotomous outcome terms, such as "response," "remission," and "recovery" are central to the design, interpretation, and clinical application of randomized controlled trials of adolescent depression interventions. Accordingly, this scoping review was conducted to document how these terms have been defined and justified in clinical trials.

METHOD

Bibliographic databases MEDLINE, Embase, APA PsycInfo, and CINAHL were searched from inception to February 2020 for randomized controlled trials evaluating treatments for adolescent depression. Ninety-eight trials were included for data extraction and analysis.

RESULTS

Assessment of outcome measurement instruments, metric strategies, methods of aggregation, and measurement timing, yielded 53 unique outcome definitions of "response" across 45 trials that assessed response, 47 unique definitions of "remission" in 29 trials that assessed remission, and 19 unique definitions of "recovery" across 11 trials that assessed recovery. A minority of trials (N = 35) provided a rationale for dichotomous outcomes definitions, often by citing other studies that used a similar definition (N = 11). No rationale included input from youth or families with lived experience.

CONCLUSION

Our review revealed that definitions of "response," "remission," "recovery," and related terms are highly variable, lack clear rationales, and are not informed by key stakeholder input. These limitations impair pooling of trial results and the incorporation of trial findings into pragmatic treatment decisions in clinical practice. Systematic approaches to establishing outcome definitions are needed to enhance the impact of trials examining adolescent depression treatment.

How have predictors, moderators, mediators, treatment response, remission and resistance been defined and measured in randomised controlled trials for adolescent depression? A scoping review protocol

INTRODUCTION

Among randomised controlled trials for depressed adolescents, the extent of variation in how depressive symptom outcomes are defined is unknown. The variability in which potential predictors of these outcomes are tested is also unclear. This paper is a protocol describing the methods of a planned scoping review. The scoping review will examine and summarise how change in depressive symptoms have been described in RCT treatment studies to date. This review will report the measures used to describe change in depressive symptoms and whether the measure was used as a continuous or binary outcome or both. This review will describe how dichotomous outcome terms are defined to describe change in depression severity. This review will also examine predictors, moderators and mediators of change in depressive symptoms within RCTs.

METHODS AND ANALYSIS

In this paper, we describe the protocol for our scoping review. Following the format outlined by the Preferred Reporting Items for Systematic Reviews and Meta-Analyses extension for scoping reviews, a research librarian will develop an operationalised search strategy, which we will apply to the MEDLINE, Embase, PsycINFO and Cumulative Index to Nursing and Allied Health Literature databases. We will search for papers from inception to 6 February 2020. A hand search for key citations will also be conducted. Investigator-raters will screen articles, first via the titles and abstracts and then through full-text reviews. We will include articles with randomised control design which assess the treatment of adolescents with major depressive disorder. We will systematically extract and synthesise prespecified data which includes: definition of depression used for participant inclusion, measures used to evaluate changes in depression, type of outcome used (continuous, binary or both), definitions of dichotomous terms to denote change in depression (eg, response, remission, recovery, etc) and reported predictors/moderators/mediators of change.

ETHICS AND DISSEMINATION

Ethics approval is not required. Findings will be presented in journal publications and at conferences.