Objective: Lupus anticoagulant (LA) and antiphospholipid antibodies (aPL) are suggested as risk factors for development of deep vein thrombosis (DVT) among patients without systemic lupus erythematosus (SLE). Other conditions, e.g. inflammation, are reported to induce LA and it is uncertain whether the association between LA and DVT is causal. In this study the associations between aPL, LA and inflammation were investigated in 170 consecutive patients without SLE, but with a tentative diagnosis of DVT.
Material and methods: DVT was diagnosed in 64 patients. LA was determined according to the criteria of the International Society of Thrombosis and Haemostasis. The concentration of anticardiolipin (aCL) and beta(2)-glycoprotein I (anti-beta(2)-GPI) antibodies as well as C-reactive protein (CRP) was determined with sensitive and precise methods.
Results: LA was demonstrated in 8 patients with DVT and in 10 patients without DVT, relative risk 1.33 (CI: 0.55-3.18). No significant association was observed between aCL or anti-beta(2)-GPI and DVT. Patients suffering from DVT had significantly higher concentrations of CRP than patients without DVT. However, CRP was also significantly higher in patients positive for LA than in patients without LA irrespective of the presence of DVT (p<0.001).
Conclusions: The present study supports a strong association between inflammatory reactions and development of LA in patients with suspected DVT, whereas no significant association was demonstrated between LA or aPL and DVT.