Dietary patterns and depression: protocol for evidence synthesis of relative risk data from already identified prospective observational studies.

The National Health and Medical Research Council (NHMRC) recently commissioned a scoping review to identify randomised or non-randomised prospective studies reporting on dietary patterns and incident depression/anxiety. This work was undertaken by Cochrane Australia and the endorsed protocol is also available on OSF. There were sufficient data identified in this process to move forward with an evidence synthesis for the outcome of incident depression in the adult and older adult population. The purpose of this protocol is to describe the steps to be taken with the identified publications to quantitatively assess the effect of adherence to a dietary pattern on incident depression. This evidence synthesis will inform the revision of the Australian Dietary Guidelines. The evidence synthesis proposed in this protocol does not recreate any steps of the scoping review, check rigour or completeness of searching methodologies, or comment on the scoping work already undertaken in relation to Cochrane Australia processes. Information about the search strategy can be found in the scoping review protocol on OSF. The current protocol only relates to use of data contained within the 52 eligible publications identified in the scoping review.