Immunologic markers as potential predictors of systemic autoimmune disease in patients with idiopathic scleritis.

PURPOSE To determine the clinical value of serological testing in patients with idiopathic scleritis. DESIGN Retrospective case series. METHODS Medical records of patients with scleritis seen at an institutional referral center over an 11-year period were reviewed. RESULTS Of 119 patients with scleritis seen at the University of Illinois Uveitis Clinic, 91 (76.5%) patients had no known etiology at initial presentation. Seventy of the 91 patients were tested for rheumatoid factor (RF), 19 (27.1%) of whom had a positive result. Ten (52.6%) of these RF positive patients were subsequently diagnosed with rheumatoid arthritis (RA) during a mean follow-up of 10.6 months (range, zero to 72 months), whereas only one of 51 (2.0%) RF negative patients developed RA, producing an odds ratio for developing RA in RF positive patients of 55.6 (95% confidence interval (CI) 7.8 to 369.8, P=.00001). Of the 70 patients who were tested for anti-neutrophil cytoplasmic antibody (ANCA), seven (10.0%) tested positive. Three (42.9%) of the ANCA positive patients subsequently developed Wegener granulomatosis (WG), whereas only two of 63 ANCA negative patients (3.2%) developed WG during a mean follow-up of 8.4 months (range, zero to 72 months). The odds ratio for developing WG in patients with idiopathic scleritis and a positive ANCA screen compared with a negative ANCA was 22.9 (95% CI 3.4 to 154.2, P=.006). CONCLUSIONS The likelihood of patients with idiopathic scleritis developing RA and WG was increased if they had a positive RF or ANCA, supporting the role of immunologic marker testing in patients who present without systemic disease.