SP134PREDICTIVE VALUE OF ANTI-C REACTIVE PROTEIN ANTIBODIES IN LUPUS NEPHRITIS

Abstract

Introduction and Aims: Lupus nephritis (LN) is a severe manifestation of systemic lupus erythematosus (SLE). It has been shown that antibodies against monomeric C reactive protein (aCRP‐Ab) might play role in pathogenesis of LN. The aim of this study was to assess the possible association between baseline levels of aCRP‐Ab at the time of renal biopsy and therapeutic response in long term follow up. Methods: Patients (n=29;median age 31 years; M/F 3/26) with established diagnosis of SLE according to American College of Rheumatology criteria and newly diagnosed active LN were enrolled to the study between 2005‐2010. Response to therapy was assessed with the respect to baseline aCRP‐Ab positivity after one and two years of treatment; median length of follow up was 5.9 years. Response to therapy was measured according to the European consensus criteria. At least partial response after the first year and second year of treatment was considered as a good outcome and no response to treatment, renal flare and end stage renal disease (ESRD) as a poor outcome. Renal flare was defined based on intention‐to‐treat principles. In the follow up we counted renal flares, at least one flare was considered as a poor outcome. Levels of aCRP‐Ab were measured by using an in‐house ELISA method. Results: Patients with baseline positivity of aCRP‐Ab (n=13) had a very high risk of renal flare or no response to therapy after two years of therapy compared to aCRP‐Ab negative patients (OR;95%CI =13.7;1.22‐770.87, p=0.014). In the long‐term follow up 5/10 of baseline aCRP‐Ab positive patients experienced at least one flare, while only 2/ 13 patients relapsed in the baseline aCRP‐Ab negative group. One patient progressed to ESRD in each group. This difference reached only borderline statistical significance, most likely due to low number of patients involved (OR;95%CI = 5.07; 0.58‐71.07, p=0.092). Conclusions: aCRP‐Ab seem to predict worse outcome after two years of standard therapy, while its role for long‐term risk prediction requires further and larger studies.