Role of plasma fibrinogen in assessing disease activity of patients with gout.

Background: Gout is an inflammatory disease characterized by the deposition of monosodium urate (MSU) in synovial fluid and other tissues. Many studies have shown that the activation of coagulation system had been proposed correlated with systemic inflammation. The concentrations of plasma fibrinogen and D-dimer are increased in abnormal coagulation, emerging as available indicators to predict systemic inflammation. The aim of this study is to reveal the predictive value of plasma fibrinogen, D-dimer in the disease activity of gout patients.

Methods: This retrospective study included 334 gout patients and 101 age- and gender- matched healthy controls. The gout patients were divided into two groups according to the gout activity score (GAS = 0.09 × last 12 month attacks + 1.01 × sUA + 0.34 × VAS patient + 0.53 × ln(1 + tophi number). The remission group included 46 patients with GAS of lower than 2.5 and the active group included 288 patients with GAS of 2.5 or higher. Clinical and laboratory data were recorded. The correlations between plasma fibrinogen, D-dimer and GAS were analyzed by Spearman's correlation analysis and Partial correlation analysis. Receiver operating characteristic (ROC) was used to evaluate the diagnostic value for the active group compared with remission group. The predictive value of fibrinogen, D-dimer to the disease activity of gout patients was tested by Binary logistic regression analysis.

Results: Plasma fibrinogen and D-dimer in gout patients (3.66 (2.88, 5.20), 0.29 (0.22, 0.80)) were increased as compared with the control group (2.88 (2.51, 3.24), 0.22 (0.22, 0.32), both P < 0.001). Fibrinogen and D-dimer in active group (3.91 (3.00, 5.53), 0.34 (0.22, 0.86)) were higher than those in remission group (2.88 (2.34, 3.22), 0.22 (0.22, 0.26), both P < 0.001)). Plasma fibrinogen, D-dimer, ESR and CRP were positively correlated with GAS (r = 0.606, r = 0.419, r = 0.570, r = 0.440, all P < 0.001). ROC curve showed fibrinogen yielded a highest AUC than D-dimer, ESR, CRP. In addition, the optimal cutoff value of fibrinogen for active group was 3.60, with a specificity of 89.1% and sensitivity of 58.3%. Binary logistic regression analysis showed fibrinogen (odds ratio = 2.71, 95% confidence interval: 1.28-5.74, p = 0.011) was a predictor for gout disease activity.

Conclusion: Fibrinogen was increased in active gout group. Fibrinogen can serve as a reliable inflammatory marker for monitoring inflammatory response and disease activity in gout patients.