Effect of alcohol intake on the development of mild cognitive impairment into dementia: A protocol for systematic review and dose–response meta-analysis

OBJECTIVE: To assess the dose–response relationship between alcohol consumption and the progression of MCI to dementia. METHOD: This study adheres to the Preferred Reporting Items for Systematic Reviews and Meta analysis for Protocols. Chinese Biomedical Literature Database (CBM), PubMed, Cochrane Library, EMBASE will be searched for all relevant published articles, with no restrictions on the year of publication or language. Case–control and cohort studies explored the relationship between alcohol exposure and the incidence of dementia in patients with MCI will be included. Study selection, data collection and assessment of study bias will be conducted independently at each level by a pair of independent reviewers. The Newcastle-Ottawa Scale (NOS) tool will be used for the risk of bias assessment. The methodological quality of systematic review will be based on A measurement Tool to Assess Systematic Review (AMSTAR 2). The Grading of Recommendations Assessment Development and Evaluation (GRADE) system will be used to assess the quality of evidence. Stata 15.0 will be used for general meta-analysis and exploring the dose–response relationship. Piecewise linear regression model and the restricted cubic spline model will be used for nonlinear trend estimation, and the generalized least-square method will be used to estimate the parameters. DISCUSSION: This dose–response meta-analysis is the first to investigate the dose–effect relationship between alcohol exposure and the incidence of dementia in patients with MCI, providing a comprehensive understanding of the prevention of alcohol-related cognitive impairment. REGISTRATION: The dose–response meta-analysis is registered in the PROSPERO (CRD42019127226) international prospective register of systematic review.