Association between rheumatoid arthritis and blood lipid levels: An integrated epidemiological observational analysis...

The association between rheumatoid arthritis (RA) and blood lipids remains controversial.

This study aimed to investigate the association between RA and blood lipids by integrating observational and Mendelian randomization (MR) analyses.

The association between the prevalence of RA and blood lipid levels was examined using data from the National Health and Nutrition Examination Survey (NHANES) (n = 24,345). Subsequently, the causality between RA and lipid and apolipoprotein levels was inferred in a 2-sample MR framework. Genetic instruments for RA (13,261 RA cases and 43,823 controls), lipids (n = 121,577), and apolipoproteins (n = 121,577) were obtained from large-scale genome-wide association studies. The statistical significance of the MR effect estimates was determined using a false discovery rate (FDR) with a <5% threshold to adjust for multiple testing.

In the NHANES cohort, RA was associated with lower total cholesterol (TC) (β -0.08; 95% CI -0.15, -0.02) and low-density lipoprotein cholesterol (LDL-C) (β -0.11; 95% CI -0.18, -0.05) levels after adjusting for potential confounders. In the 2-sample MR analyses, genetic liability to RA was associated with lower levels of TC (β -0.013; 95% CI -0.022, -0.004, FDR 0.011), LDL-C (β -0.017; 95% CI -0.027, -0.008, FDR 0.003), and apolipoprotein B (Apo B) (β -0.016; 95% CI -0.028, -0.004, FDR 0.015).

RA is causally associated with lower TC, LDL-C, and Apo B levels. Clinicians should cautiously interpret lower atherogenic lipid levels in patients with RA, as these may indicate underlying disease processes.