ESR1 and rheumatoid arthritis: Age-based subgroup analysis showed that both older (MD = 5.60; 95% CI: 1.76-9.44; P < 0.001) and younger individuals (MD = 9.95; 95% CI: 2.86-17.04; P < 0.001) in the RA-ILD group had significantly higher ESR levels compared to the RA group.