Assessment of blood clot formation and platelet receptor function ex vivo in patients with primary Sjögren's syndrome

OBJECTIVES: Primary Sjögren's syndrome (pSS) shares clinical features and pathogenetic mechanisms with systemic lupus erythematosus (SLE). SLE is associated with an increased thromboembolic risk; however, it is unclear whether pSS patients are susceptible to thromboembolic diseases. In this study, we examined ex vivo blood clot formation (clot strength, rates of clot formation and lysis) in pSS using thromboelastography (TEG) and platelet aggregation to common agonists using multiple electrode aggregometry (MEA). We also investigated the relationship between TEG/MEA parameters and clinical/laboratory features of pSS. DESIGN: Case control. SETTING: Secondary care, single centre. PARTICIPANTS: 34 pSS patients, 11 SLE patients and 13 healthy volunteers (all women) entered and completed the study. PRIMARY AND SECONDARY OUTCOME MEASURES: Primary outcomes: TEG and MEA parameters between three subject groups. Secondary outcomes: The relationships between TEG/MEA and clinical/laboratory parameters analysed using bivariate correlation analysis with corrections for multiple testing. RESULTS: All TEG and MEA parameters were similar for the three subject groups. After corrections for multiple testing, interleukin (IL)-1α and Macrophage inflammatory proteins (MIP)-1α remain correlated inversely with clot strength (r=−0.686, p=0.024 and r=−0.730, p=0.012, respectively) and overall coagulability (r=−0.640, p=0.048 and r=−0.648, p=0.048). Stepwise regression analysis revealed that several cytokines such as MIP-1α, IL-17a, IL-1α and Interferon (IFN)-γ may be key predictors of clot strength and overall coagulability in pSS. CONCLUSIONS: Clot kinetics and platelet receptor function are normal in pSS. Several cytokines correlate with clot strength and overall coagulability in pSS.