Persistent eosinophilia in rheumatoid arthritis: a prospective observational study

Eosinophilia is an uncommon manifestation in Rheumatoid arthritis (RA), and there is a paucity of data regarding the relationship of eosinophilia with disease-related factors. We prospectively evaluated the clinical and disease-specific characteristics of RA patients with eosinophilia. Consecutive patients with RA with an absolute eosinophil count ≥ 500/mm³ without an apparent cause for eosinophilia, were investigated for parasitic infestation. Patients with a definite parasitic infestation received targeted therapy, and the rest were treated with albendazole empirically. The RA disease-specific characteristics of the patients with persistent eosinophilia were compared with the patients without eosinophilia. Of the 160 patients with eosinophilia, 30 patients (19%) had allergic diseases, six patients had bronchiectasis, and one patient had hypereosinophilia of undetermined significance. Intestinal helminthiasis was found in 34 patients (21%). Eosinophilia was unexplained in 89 patients (56%) and it resolved after empirical albendazole therapy in about two-thirds (58 patients). Thirty-one patients had persistent eosinophilia. Nonsteroidal anti-inflammatory drug and disease-modifying antirheumatic drug modification did not show any effect on eosinophilia. The disease-related characteristics were similar between patients with persistent eosinophilia and those without eosinophilia. Eosinophilia is due to secondary causes in the majority of RA patients, and the most common cause in our setting is an intestinal helminthic infection. Persistent eosinophilia in our cohort of RA did not indicate a more severe disease phenotype.