Statistical analyses were performed using
SPSS v.22 and
Stata 13.0. The data from the discovery and validation stages were calculated independently. Group differences in categorical data, such as sex, clinical subgroups, and apolipoprotein ε4 (
APOE ε4) carrier distributions, were analyzed using the χ
2 test. Group differences in numerical data, such as the concentrations of biomarkers, were analyzed with Welch's
t‐test or analyses of variance. The correlative analysis was performed using a linear regression model. In the discovery and validation stage, after the generation of an adjusted receiver operating characteristic (ROC) curve, the predicted values were calculated using a binary logistic regression model with age, sex, and
APOE ε4 status as covariates.
43 For the preclinical AD and FAD dataset, the tolerance, variance inflation factor, eigenvalue, and condition index were calculated to examine the multicollinearity in the linear regression models. To avoid multicollinearity when establishing the predict models of synaptic proteins, ridge regression was performed in
Stata 13.0 with elastic regress module. The age, sex, and
APOE ε4 status was adjusted in the ridge regression. The dataset was randomly split into training dataset (0.67 of total) and test dataset (0.33 of total) using
SPSS v.22. All tests were two‐tailed, and the level of significance was set to
P < .05.
Jia L., Zhu M., Kong C., Pang Y., Zhang H., Qiu Q., Wei C., Tang Y., Wang Q., Li Y., Li T., Li F., Wang Q., Li Y., Wei Y, & Jia J. (2020). Blood neuro‐exosomal synaptic proteins predict Alzheimer's disease at the asymptomatic stage. Alzheimer's & Dementia, 17(1), 49-60.