Applying the Behavioural Science Approach to Realist Reviews and Evaluations (BARR/E): A Protocol for a Review of Antidepressant Deprescribing Interventions in Primary Care.

1-in-5 people are prescribed an antidepressant for a common mental disorder (CMD), such as depression or anxiety. Most people do not require lifelong treatment, however more than half continue antidepressants for ≥2 years despite no ongoing symptoms. Antidepressant deprescribing is not routine practice in primary care and healthcare professionals report barriers including concerns about withdrawal effects, perceived patient attachment to antidepressants and limited availability of withdrawal-informed support. Drawing on realist principles and behavioural science, this review will identify behavioural mechanisms and contexts from academic and grey literature to formulate programme theories describing how to facilitate primary care healthcare professionals to deprescribe antidepressants. The review is guided by the Behavioural science Approach to Realist Reviews/Evaluations (BARR/E) and will follow five steps: (1) define the review scope, (2) develop initial programme theories, (3) evidence search, (4) selection and appraisal and (5) data extraction and synthesis. Peer-reviewed literature will be identified through MEDLINE, Embase, PsycINFO and CINAHL, supplemented by grey literature identified through expert consultation, database and citation searches. The evidence will be assessed for relevance, rigour and richness, and data extracted and synthesised to develop context-mechanism-outcome configurations. Findings will be reported in accordance with RAMESES quality and publication standards.