Background Red blood cell distribution width (RDW) is a biomarker quantifying the variability of red blood cell size (anisocytosis) in the peripheral blood. High RDW is associated with inflammatory burden and it has been suggested as a potential marker for cardiovascular prognosis, mortality, or reflecting renal function in the various clinical conditions ¹. A recent study found the significant association between serum uric acid level and RDW in patients with untreated essential hypertension². Gouty arthritis is an acute and severe inflammatory arthritis attributable to hyperuricemia, and closely associated with renal dysfunction and cardiovascular diseases. However, few studies have yet investigated the clinical significance of RDW in patients with gout.

Objectives The aim of this study was to investigate the potential association of RDW value with clinical features in patients presenting with acute gout attack.

Methods The medical records of patients who visited emergency room of Seoul National University Bundang Hospital for acute gout attack, from March 2003 to April 2014, were retrospectively reviewed. Cases were stratified into three groups according to the RDW tertiles (<12.9%, 12.9-13.4% and >13.4%) and clinically relevant differences were evaluated by the ANOVA test or the chi-square test. The Pearson's correlation approach was used to analyze the correlation between two continuous variables. To identify significant determinants influencing RDW, we used multiple linear regression analysis.

Results Two-hundred and thirty-six patients with acute gout attack were included. The mean age was 49.38±16.85 years and the male ratio was 92.3% (n=218). The patients in the highest RDW tertile tended to be older, had higher levels of hemoglobin and lower levels of albumin, and had more recurrence of gout attack and renal impairment. RDW showed significant weak positive correlation with age (γ=0.224, p=0.001) and creatinine level (γ=0.237, p<0.001) and negative modest correlation with albumin level (γ= -0.332, p<0.001) in gout attack. However, RDW was not significantly correlated with serum uric acid level and acute phase reactants. In multiple linear regression analysis, increase in RDW was independently associated with recurrence of gout attack (p<0.001) and presence of chronic kidney disease (p=0.009) (Table 1).

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Conclusions Our data shows that high RDW in acute gout attack is related to the recurrence of gout attack and coexistence of chronic kidney disease. In acute gout attack, RDW, an easy and quick measurable index, may represent renal dysfunction rather than inflammatory burden or uric acid level, and physicians who treat acute gouty arthritis with high RDW should pay attention to the recurrence of gout attack and treatment.

References

1. Lippi G, Targher G, Montagnana M, Salvagno GL, Zoppini G, Guidi GC. Relation between red blood cell distribution width and inflammatory biomarkers in a large cohort of unselected outpatients. Arch Pathol Lab Med 2009;133:628-32.

2. Luo M, Li ZZ, Li YY, Chen LZ, Yan SP, Chen P, et al. Relationship between red cell distribution width and serum uric acid in patients with untreated essential hypertension. Sci Rep 2014;4:7291. DOI: 10.1038/srep07291

Disclosure of Interest None declared