AB0326 Characterizing Seronegative Rheumatoid Arthritis

Background Seronegative Rheumatoid Arthritis (RA) is a disorder associated with considerable diagnostic, prognostic and therapeutic uncertainty for many clinicians. Objectives The aim of this study is to provide a deeper understanding of the diagnosis and manifestations of rheumatoid arthritis with negative serologies. Methods The study was a retrospective chart review of electronic medical records from January, 2003 to December, 2012. Patients were identified using ICD-9 code Rheumatoid Arthritis 714.0 and at least two rheumatology clinic visits during the specified time. Charts were reviewed individually by two investigators. The inclusion criteria were a diagnosis of RA confirmed by a rheumatologist with normal values for both rheumatoid factor (RF) and anti-CCP antibodies (CCP, third generation assay). Data were collected on demographics (sex, race, smoking status), family history of rheumatoid arthritis, and laboratory values (presence of anemia, inflammatory markers) at the time of diagnosis. The presence of erosions and synovitis identified by imaging studies was assessed. In addition, the presence of extra-articular manifestations of RA including nodules, pleural or parenchymal lung disease, eye involvement and osteoporosis was recorded. The therapies (DMARD, biologic) used to treat the seronegative RA were also reviewed. Results Charts from 108 patients were reviewed. Forty-five patients were excluded based on incorrect initial diagnosis or low clinical suspicion for seronegative RA by the rheumatologist. Sixty-three patients were included in this analysis. The demographics were similar to that of our patient population with seropositive RA. Of available data, at the time of diagnosis, 25% of the patients were smokers, 13% had a family history of RA, 54% were anemic, and 76% had abnormal ESR or CRP. Seven of the 63 (11%) patients had erosions on radiography, and 6 of 63 (9.5%) patients had MRI findings of synovitis. Initial data suggest that extra-articular manifestations are infrequent in this group. Forty-eight of the 62 were initiated on a DMARD, most commonly hydroxychloroquine (16% patients) or methotrexate (29% patients) with a large percentage of patients with combination of methotrexate and hydroxychloroquine therapy (35%). Of the 63 patients, 17 (27%) patients required a biologic therapy during treatment course. Conclusions This study supports the hypothesis that clinical history and physical examination are the most important determinants in diagnosing seronegative RA. In addition to characteristic symptoms, factors which might contribute to diagnosis of RA in a patient without seropositivity include positive family history, smoking history, acute phase reactants, presence of anemia, and imaging studies. Disclosure of Interest None declared DOI 10.1136/annrheumdis-2014-eular.2163