AB0403 Factors contribute to the level uric acid in rheumatoid arthritis
Authors: S. Hannawi, I. Al Salmi, H. Hannawi
Journal: Annals of the Rheumatic Diseases (2018)

<h3>Background</h3> Uric acid (UA) is a strong correlate of renal dysfunction in rheumatoid arthritis (RA), even in the absence of crystal deposition, by causing endothelial dysfunction, intrarenal vascular disease and renal impairment. In hyper or normo-uricaemia RA, UA was the strongest independent predictor of GFR, even after adjustments for most of the potential confounding factors. Additionally, in RA patients UA had been found to be an independent predictor of hypertension and cardiovascular disease (CVD). <h3>Objectives</h3> this study aimed to investigate what could be the determinants of the UA level in RA patients. <h3>Methods</h3> RA patients with no clinically evident gout, CVD, thyroid disease, liver or renal disease were studied. Serum UA was obtained for all the patients. Renal function parameters, RA disease characteristics, inflammatory markers, and traditional CVD risk factors relation to uric acid level was examined using simple linear regression analysis. To test for the independence association between uri acid and the variables of interest, multiple model was built for the same dependent and independents variables. Statistical significance was accepted at p-value&lt;0.05. <h3>Results</h3> The study recruited 86 consecutive patients meeting the 1987 RA revised ACR criteria, attending routine outpatient clinics at the Department of Rheumatology. Basic demographics and clinical characteristics of were obtained. Of the total 86 patients, 10 (11%) were men and 77 (89%) were women. The mean age of the participants was 47±14 years, with mean RA duration of 68±87 months. 64 out of 86 participants (74%) had rheumatoid factor positive. The mean UA value was 255±86 umol/L (NR: 180–340). The mean GFR, calculated using modified MDRD (Modification of Diet in Renal Disease) formula was 133±52 ml/min/1.73m<sup>2</sup>. Using univariate analysis revealed a positive linear relationship between uric acid level and each of the age of the participants (p&lt;0.016, CI: 0.31, 2.92), age at RA symptoms onset (p&lt;0.04, CI: 0.025, 0.039), age at RA diagnosis (p&lt;0.03, CI: 0.101, 2.565), systolic blood pressure (p=0.04, CI: 0.054, 2.167), diastolic blood pressure (DBP) (p=0.02, CI: 0.322, 3.777), monocytes absolute count (p=0.014, CI: 2.510, 4.801), monocytes percentage (p=0.005, CI: 34.599, 193.595), cholesterol level (p=0.008, CI: −39.934,–6.286), Triglyceride level (p=0.04, CI: 0.064, 56.546), urea level (p&lt;0.001, CI: 9.356, 28.743), creatinine (p≤0.001, CI: 2.345, 3.960), urinary microalbumin (p=0.024, CI: 0.0296, 0.399), urinary microalbumin/creatinine ratio (p=0.006, CI: 0.791, 4.616), and ferritin level (p=0.025, CI: 0.044, 0.633). As well, univariate analysis revealed a negative linear relationship between UA level and GFR (p&lt;0.001, CI: −1.127,–0.486) Building a multiple model, including the entire variable with significant association with the UA in the univariate analysis showed that the UA level in RA is determined by GFR, microalbumin creatinine ratio, cholesterol level, monocytes count and DAS score. The adjusted R2 of the model was 54 <h3>Conclusions</h3> Whether serum uric acid is merely a marker that reflects the integration of co-morbidities and subclinical renal impairment or a true risk-causative factor for CVD outcome remains as an important question, therefore it is important to know the determinant of UA level and control it. <h3>Disclosure of Interest</h3> None declared