FRI0113 Rheumatoid arthritis and eosinophilia: the risk of lymphoproliferative malignancies and solid cancers. a study based on the copenhagen primary care differential count (copdiff) database
Authors: C. Lykkegaard Andersen, H. Vestergaard, O. W. Bjerrum, V. D. Siersma, P. Felding, H. Hasselbalch, N. de Fine Olivarius, H. M. Lindegaard
Journal: Annals of the Rheumatic Diseases (2013)

<h3>Background</h3> Cohort and population studies have indicated an association between rheumatoid arthritis (RA) and malignancies. Several mechanisms have been suggested; i) extrinsic pro-oncogenic effects of disease-modifying antirheumatic drugs, ii) intrinsic pro-oncogenic effects of disease activity and iii) surveillance bias. No study has been able to disentangle the possible effects of disease activity on lymphoma risk or identify the promoting factors. In this context, the eosinophil is an interesting candidate. Blood eosinophiliaoccurs in RA in outpatients with an estimated prevalence of 7.7% [1]and is linked to prognosis and severity of extra-articular manifestations [2]. Importantly, eosinophilia per se is associated with certain lymphoproliferative malignancies (unpublished data - CopDiff database to be presented at EULAR) <h3>Objectives</h3> To investigate whether RA is associated with risk of lymphoproliferative malignancies or solid cancers when adjusting for the potential mediator eosinophilia and several known confounders in a large primary care cohort largely unaffected by surveillance bias <h3>Methods</h3> From the Copenhagen Primary Care Differential Count (CopDiff)Database, we identified 359.950 individuals with a differential cell count (DIFF) during 2000-2007. From these individuals one DIFF was chosen at random. By linkage to the Danish National Patient Register, we identified baseline diagnoses of RA and categorized these according to time before baseline. From the Danish Cancer Registry we ascertained malignancies within three years following the DIFF. Odds ratios (ORs) and 95% confidence intervals (CIs) were computed using multivariate logistic regression and were adjusted for eosinophilia, sex, age, year, month, CRP and Charlson´s comorbidity index (CCI) <h3>Results</h3> 921 persons had recent onset (&lt;3 years) RA and 2.583 had longer disease duration (≥3 years) RA. After multivariate adjustment, RA was not associated with incident lymphoproliferative malignancies. Compared with patients without RA, ORs (95% CI) for lymphoproliferative malignancies were 0.95 (0.39-2.32) for longer disease duration and 0.69 (0.10-5.00) for recent onset. Similarly, RA was not associated with an increased risk of incident solid cancers (ORs of 1.11 (0.89-1.38) and 0.76 (0.48-1.20), respectively). These risk estimates did not alter when eosinophilia, CRP and comorbidity were excluded from the models <h3>Conclusions</h3> RA with or without eosinophilia was not associated with an increased risk of lymphoproliferative or solid cancersduring 3 years of follow-upin a primary care population. In contrast to previous studies, this cohort is largely unaffected by surveillance bias <h3>References</h3> Panush, R.S. et al. Ann Intern Med, 1971. 75(2): p. 199-205 Kargili, A. et al. Rheumatol Int, 2004. 24(6): p. 321-4 <h3>Disclosure of Interest</h3> C. Lykkegaard Andersen: None Declared, H. Vestergaard Grant/research support from: BMS, Novartis, O. Bjerrum: None Declared, V. Siersma: None Declared, P. Felding: None Declared, H. Hasselbalch: None Declared, N. de Fine Olivarius: None Declared, H. Lindegaard Grant/research support from: Roche, MSD, BMS, Merck