Effects of different kinds of anti-Alzheimer’s disease drugs on cognitive improvement: protocol for a systematic review and network meta-analysis of phase III clinical trials

Abstract

Background: Alzheimer’s disease is a neurodegenerative disease characterized by progressive cognitive decline and dysfunction of independent living ability, with huge economic and healthy burden worldwide. However, there is still a lack of effective long-term drugs to improve cognitive function and reduce or halt disease progression. Phase III clinical trials of anti-AD drugs based on different hypotheses were in the pipeline, and this protocol for a systematic review and meta-analysis aims to determine what is the most effective direction for the development of drugs on cognitive improvement. Methods/design: We will search the following literature databases for eligible studies from inception to December 2021: Ovid MEDLINE, Ovid Embase, PubMed MEDLINE, and Cochrane Central Register of Controlled Trials. Google Scholar, ClinicalTrials.gov registration platform, and the AlzForum website will also be searched for additional studies. Studies will be included irrespective of publication status or language. Phase III clinical trials reporting on the effect of anti-AD drugs on participants with AD will be included. Two independent reviewers will screen the hit articles and identify phase III clinical trials, extract data, and assess the quality of each study individually. The Cochrane Risk of Bias tool 2 (RoB 2) will be used to assess the risk of bias. For each kind of drugs based on the corresponding hypothesis, we will compare the study design and demographic features of the clinical trials and include appropriate studies in the network meta-analysis. The primary outcomes will be the indicators of cognitive improvement. The secondary outcomes will be activities of daily living, neuroimaging changes, biomarkers, and safety. Through network meta-analysis, we will suggest the hypothesis that most likely to improve cognitive function and provide the ranks of all kinds of drugs. We will give recommendation grade of each comparison using the Confidence In Network Meta-Analysis (CINeMa) tool. Discussion: This study will provide helpful evidence for further drug development and clinical practice for treating Alzheimer’s disease. Systematic review registration: PROSPERO CRD42021251507.