The purpose is to determine the hypercoagulable phenotype by thrombinography associated to an increased risk of symptomatic and objectively confirmed first venous thrombotic event. This is a case-control study in a population with patients having systemic lupus erythematosus (SLE) and/or antiphospholipid antibodies (APL).

Secondary purposes are:

1. To determine the frequency of hypercoagulable phenotype in study population;
2. To analyze the sensibility: consequences of variation of hypercoagulable phenotype threshold on the importance of risk;
3. To identify (genetic and not) factors for hypercoagulable phenotype and their frequency in different groups.

Inclusion Criteria:

Cases :

• Patients with SLE and/or APL and first documented deep vein thrombosis episode (minimum 6 months, maximum 6 years)
• Any weight and height
• Absence of current anticoagulant treatment but possibility of platelet function inhibitory treatment; actual guidelines suggest long-term anticoagulant treatment in patients with first episode of venous thrombosis and having APL; however, these patients can be studied if they are in one of these circumstances: 1/ "inconvenient" stop by patient, 2/ aspirin decided by doctor after prolonged treatment

Controls:

• Patients with SLE and/or APL without thrombosis (venous or arterial)
• Any weight and height
• Possibility of platelet function inhibitory treatment (primary prophylaxis of arterial manifestations)

Exclusion Criteria:

Cases and Controls :

• Pregnancy
• Refusal of consent
• Difficulty of follow-up (not sufficient motivation)