Diagnostic accuracy of blood biomarkers for Alzheimer’s disease and amnestic mild cognitive impairment: A meta-analysis

•To examine DOR of blood biomarkers for detecting AD and aMCI.•Plasma Aβ42 and plasma tau was satisfactory for diagnosing AD.•Plasma tau using IMR increased the accuracy for high diagnostic efficacy in AD. To examine the diagnostic accuracy of blood-based biomarkers for detecting Alzheimer’s disease (AD) and amnestic mild cognitive impairment (aMCI). Seven electronic databases were comprehensively searched for studies evaluating the diagnostic accuracy of blood-based biomarkers for detecting AD or aMCI up to July 31, 2020. The pooled sensitivity, specificity, and the diagnostic odds ratio (DOR) were calculated using a hierarchical summary receiver operating characteristic model. A total of 17 studies (n = 2,083) were included. In differentiating patients with AD from the controls, the DOR was 32.2 for the plasma Aβ42 (sensitivity = 88 %, specificity = 81 %), 29.1 for the plasma Aβ oligomer (sensitivity = 80 %, specificity = 88 %), and 52.1 for the plasma tau (sensitivity = 90 %, specificity = 87 %). For differentiating aMCI from the controls, the DOR was 60.4 for the plasma Aβ42 (sensitivity = 86 %, specificity = 90 %) and 49.1 for the plasma tau (sensitivity = 79 %, specificity = 94 %). The use of ultra-high sensitive technology explained the heterogeneity in the diagnostic performance of blood-based biomarkers (P = .01). We suggest that blood-based biomarkers are minimally invasive and cost-effective tools for detecting AD; however, the evidence for detecting aMCI was still limited.