2.4 Statistical Methods
We conducted the primary MR analysis using the fixed effects
inverse-variance weighted (IVW) method to assess the causal
relationships between herpes viruses and leukocytoclastic angiitis. This
method provides robust causal estimates, although it is somewhat
sensitive to pleiotropy. In addition, we performed supplementary
analyses using the weighted median method and MR-Egger regression(14, 15). In the main analyses, we calculated odds
ratios (ORs) and 95% confidence intervals (CIs) for the IVs.
The heterogeneity was evaluated in the odds ratio using Cochran’s Q test
and visually inspected a funnel plot to assess symmetry, which indicates
the absence of systematic bias (16). We also conducted
an MR-Egger intercept analysis to assess the presence of directional
pleiotropy. Furthermore, we performed a leave-one-out sensitivity test
to evaluate the impact of individual SNPs on the results, mitigating
potential bias (14, 16, 17).
All statistical analyses were carried out using R Studio (v.4.3.1), with
the MR analysis conducted using the ‘TwoSampleMR’ package(18). (Figure. 1)