Mendelian randomization suggests potential causal link between severe COVID-19 and polymyositis risk

This single-center cohort study of 108 hospitalized patients with PCR-confirmed COVID-19 employed a multilevel exploratory framework combining Mendelian randomization (MR), multi-omic analyses, and retrospective cohort analysis. The study examined the relationship between severe COVID-19 (as the exposure) and polymyositis risk, comparing severe versus non-severe COVID-19 cases. The primary MR analysis using inverse-variance weighted (IVW) method suggested a potential causal effect, with a genetically predicted increase in severe COVID-19 risk associated with higher polymyositis odds (OR = 1.65, 95% CI: 1.36–2.01). Secondary analyses explored mediating biomarkers and differences in hematological indices between severity groups, though specific results for these outcomes were not reported in the provided data.

Safety and tolerability data were not reported for this observational analysis. The study had several important limitations: causal inference remains limited by potential confounding inherent in observational studies, and the research adopted an explicitly exploratory framework. The single-center design with 108 patients further limits generalizability.

For clinical practice, these findings represent preliminary evidence requiring substantial validation. The MR analysis suggests a potential biological link between severe COVID-19 and subsequent polymyositis risk, but clinicians should interpret this cautiously. The study does not establish clinical management pathways but may inform future research into post-COVID inflammatory complications. More rigorous prospective studies are needed to confirm any causal relationship and quantify actual clinical risk.