[Association between anemia and rheumatoid arthritis: a cross-sectional and Mendelian randomization study]

Objective To investigate the correlation between anemia and rheumatoid arthritis (RA), and to analyze the potential impact and causal relationship between them. Methods Using data from the National Health and Nutrition Examination Survey (NHANES) database, a logistic regression model was constructed to assess the association between anemia and RA; subgroup analysis was performed to verify the stability of the results. Subsequently, a two-sample mendelian randomization (MR) analysis was conducted to explore the bidirectional causal relationship between anemia and RA. Results Multivariate logistic regression analysis revealed a positive correlation between anemia and RA (OR=1.21, 95%CI: 1.05-1.40), and subgroup analysis further confirmed the stability of these results. Furthermore, MR analysis indicated a bidirectional causal relationship between anemia and RA, with no observed evidence of horizontal pleiotropy or heterogeneity. Conclusion Anemia and RA demonstrate a significant correlation and a bidirectional causal relationship at multiple levels.