Statistical Analysis
We described data as mean (standard deviation) or number (percentage)
for continuous and categorical variables, respectively. We employed the
Student t-test and Chi-squared or Fisher’s exact tests to compare
continuous and categorical variables between the study groups,
respectively. For calculating odds ratio (OR) and 95% confidence
interval (CI), we fitted a binary logistic regression model to the data.
In the case group, we fitted a linear regression model to the data for
predicting serum vitamin B12 in these patients. We included age, sex,
TSH, and the frequency of lifetime syncopal episodes (≥3 versus
<3 episodes) as independent variables in the model. All
analyses were done using R version 4.0.3 (2020-10-10). The significance
level was set at 0.05 with two-sided tests for all hypotheses.