The presence of eosinophilia in peripheral blood has been considered by some authors as an indicator of bad prognosis in patients with rheumatoid arthritis (RA); however, the methodology and the number of patients included in those studies were not appropriate.
To determine the prevalence and possible causes of eosinophilia in patients with RA, and its relationship with a more severe disease.
Patients with RA (American College of Rheumatology '87) were included, demographic, clinical, and laboratory data were collected. The presence of eosinophilia was defined as an eosinophil absolute count above 350/mm. Disease activity, health assessment questionnaire, and hand x-rays were performed in all patients. A coproparasitologic test and serology for Toxocara by enzyme-linked immunosorbent assay (ELISA) were determined in patients with eosinophilia.
One hundred nine patients were included, 95 women (87.2%), mean age 50.6 +/- 13 years, mean disease duration 10.8 +/- 7.6 years. Eight patients (7.33%) showed eosinophilia. When demographic and clinical characteristics of patients with or without eosinophilia were compared, the former showed a higher erythrocyte sedimentation rate levels and significantly more frequency of dry mouth, anal pruritus, and paresthesia. The remaining clinical variables, as well as radiologic structural damage were comparable. Parasites in feces (Ascaris lumbricoides and Enterobius vermicularis) were found in 2 patients with eosinophilia. Seven patients with eosinophilia (87.5%) versus 4 (19%) without eosinophilia showed positive serology for Toxocara (P = 0.001).
The frequency of eosinophilia in our population of patients with RA was 7.33%. It was not an indicator of severity of the disease and in all cases evidence for secondary causes (parasitosis) was found.