Association of cognitive reserve with stroke outcome: a protocol for a systematic review

INTRODUCTION: The concept of cognitive reserve (CR) was introduced to account for individual differences in the clinical manifestation of neurodegenerative diseases. Though several mechanisms and risk factors are shared between neurodegeneration and stroke, the effect of CR on poststroke functional outcome has been poorly addressed. This systematic review aims to synthesise the available research evidence on the association of CR with stroke outcome, in order to implement the understanding of interindividual variability in stroke outcome and to improve its prediction. METHODS AND ANALYSIS: Cochrane Library, Embase, PubMed, Web of Science and reference lists of relevant literature will be searched for publications on CR proxies (eg, education, years of education, occupational attainment, premorbid intelligence) and stroke outcome, published between 1 January 1980 and 10 March 2022. Two reviewers will independently perform the study selection, data extraction and quality assessment. Disagreements between reviewers will be resolved by a third independent reviewer. The Quality In Prognosis Studies tool will be used to assess the quality of each included study. The primary outcome will be functional outcome after stroke assessed with modified Rankin Scale, activities of daily living (eg, Barthel Index), National Institute of Health Stroke Scale, dichotomised as favourable versus not favourable as well as reported as continuous or ordinal variables. Qualitative and quantitative findings will be summarised and, if possible, data will be synthesised using appropriate meta-analytical methods. The quality of evidence will be assessed using the Grading of Recommendations Assessment, Development and Evaluation framework. ETHICS AND DISSEMINATION: No ethical approval is required as it is a protocol for a systematic review and the data used will be extracted from published studies. The findings from this systematic review will be disseminated in a peer-reviewed scientific journal and presented at conferences. The data will be made freely available. PROSPERO REGISTRATION NUMBER: CRD42021256175.