SAT0149 Is established seronegative rheumatoid arthritis even a mild form of the disease?
Authors: L. D. Fajardo Hermosillo
Journal: Annals of the Rheumatic Diseases (2018)

<h3>Background:</h3> Established Seronegative Rheumatoid Arthritis (SNRA) was considered a mild form of the disease with a good response to therapy on the past<sup>1</sup>. Lately evidence indicates this form of arthritis in early stage is serious and should not be underestimated in terms of disease activity and radiographic damage<sup>2</sup>. By other hand early SNRA presents shorter symptoms duration and different response to therapy compare to seropositive (SP) patients<sup>3,4</sup>. At present, the influence of seronegative (SN) status of clinical course and treatment choice is still controversial. Data of this issue are scarce and often insufficiently powered. <h3>Objectives:</h3> To determine demographical, clinical and treatment differences between established SN and SP Rheumatoid Arthritis (RA) in a Mexican cohort. <h3>Methods:</h3> 511 patients with established RA (&gt;2 years from time at onset of diagnosis) that fulfilled ACR/EULAR 2010 criteria (≥18 years) from a Mexican cohort from 2012 to 2017 were examined. Patients without presence of rheumatoid factor (RF) and anti-citrullinated protein antibodies (ACPA) were considered SN. Demographic factors, clinical features, disease activity measured using DAS28, functional status, comorbidities and pharmacologic treatments were examined for patients with established SN and SP RA. Charlson's clinical co-morbidity index was used to analyze comorbidities. Chi-square and Student-t test was performed by univariate analysis and logistic regression was used by multivariate analysis, both were adjusted for age and gender. Standard deviation and mean of modified Charlson's index was obtained by ANOVA analysis.Statistical test were conducted at 5% level of significance. <h3>Results:</h3> Of 511 patients with established RA 89% were women. The mean age [standard deviation (SD)] was 55.6 (11.8) years. The mean of time at onset of RA (SD) was 12.1 (8.7) years. A total of 77 (15.1%) patients had established SNRA. In the univariable analyses established SNRA patients were more likely to have shorter time at onset of RA, minor disease activity and radiographic progression, lesser extra-articular and sicca manifestations, reduced demand of hip and knee arthroplasty, also present lower comorbidities including osteoporosis and fibromyalgia, besides to use fewer methotrexate and corticosteroids. As expected, the modified Charlson's comorbidity index score was lower in established SNRA patients. No differences were found for use of biologic agents in both groups. In multivariable analyses, minor disease activity (OR 0.33, 95% CI 0.17–0.60, p≤0.001), less frequently use of methotrexate (OR 0.38, 95% CI 0.17–0.82, p=0.014) and minor radiographic progression (OR 0.13, 95% CI 0.40–0.39, p≤0.001), remained significant in established SNRA patients. <h3>Conclusions:</h3> This study suggests that established SNRA present less disease activity and radiographic damage as well as fewer use of MTX than established SPRA. However differences in activity disease and response to treatment can be found in early stages of RA not included in this study. Therefore early SNRA cannot be considered to be a generally mild form of the disease like as established SNRA. These observations must be confirmed in larger studies including early stages of RA. <h3>References</h3> [1]Nat Rev Rheumatol2012;8:144–152. [2]J Rheumatol2014;41;2361–2369. [3]Ann Rheum Dis2012;71:245–248. [4] Arthritis Res Ther2014;16: R13. <h3>Disclosure of Interest:</h3> None declared