Potential advantages of combining randomized controlled trials with qualitative research in mood and anxiety disorders - A systematic review

INTRODUCTION: Most randomized controlled trials (RCTs) of mood and anxiety disorders employ solely quantitative methods. Supplementing quantitative data with qualitative methods, a so-called mixed-method approach, would seem useful, however this area has not been rigorously reviewed. We undertook a systematic review of RCTs of mood and anxiety disorders that employed concurrent quantitative data collection and qualitative methods exploring the participants' perspective, with the aim of 1. determining the number of such studies, 2. describing study characteristics, and 3. identifying potential advantages of a mixed-method approach.

METHODS: Following PRISMA guidelines, a systematic literature search for RCTs of mood and anxiety disorders, concurrently applying quantitative and qualitative methods, was conducted using EMBASE, PsycINFO and Pubmed, from their inception to February 2021. Categories of potential advantages of this mixed method approach were developed.

RESULTS: A total of 45 RCTs were included. The qualitative components typically included 10-40 participants, mostly consisting of interviews after the intervention. The majority of papers did not state a specific rationale for using a mixed method approach. Four categories of advantages emerged: 1. determine acceptability/feasibility, 2. investigate efficacy, 3. inform implementation in clinical practice and 4. generate new hypotheses based on the combination of quantitative and qualitative data.

LIMITATIONS: Lack of cross-referencing and consistent terminology challenged identification of relevant publications.

CONCLUSION: There are a number of potential advantages of applying mixed method approaches in RCTs within psychiatric research. Intentional consideration of such advantages early in trial design may increase the likelihood of gaining added value.