The coexistence of familial Mediterranean fever (FMF) in systemic lupus erythematosus (SLE) patients - A cross sectional study.

Background: Systemic lupus erythematosus (SLE) is a systemic autoimmune inflammatory disease characterized by antibody production against a myriad of autoantigens. Familial Mediterranean fever (FMF) is a genetic autoinflammatory disorder, triggered by FMF-associated point genes mutations. It has been hypothesized that the two conditions rarely coexist.

Aim: The aim of this study was to examine the proportions of FMF among SLE patients compared with the general population without SLE. We hypothesized that the proportion of FMF among SLE patients might be higher than the general population.

Methods: To conduct this cross-sectional study, data of adult patients with a physician diagnosis of SLE were retrieved from Clalit Health Services database, the largest Health Maintenance Organization in Israel, serving 4,400,000 members. Chi-square and T-test was used for univariate analysis.

Results: The study population included 4,886 SLE patients and 24,430 age and sex matched controls. Within the SLE group we detected a significantly higher proportion of FMF patients compared with non-SLE controls (0.68% and 0.21% respectively; p < 0.001).

Conclusions: Our study indicated that FMF is more prevalent in an Israeli population of SLE patients.