[Resistance to activated protein C in venous thromboembolic complications. Incidence and clinical manifestations].

OBJECTIVES

The frequency of activated protein C resistance is not well established for patients with venous thromboembolic disease. We studied resistance to activated protein C in patients with a past history of deep vein or superficial vein thrombosis.

METHODS

Activated protein C resistance was measured in 175 patients (37 males, 138 females; mean age 40.9 +/- 13.8 years; range 15-77) who had suffered a venous thromboembolic event more than one month earlier. Exclusion criteria were malignancy, known autoimmune disease or known coagulopathy. A control population of 50 healthy subjects were also tested to establish a normal lower limit (mean ratio minus 2 SD).

RESULTS

The lower limit was established at 2.14. According to this definition, there were 29 thromboembolic patients who were resistant to activated C protein (17%). Two of the subjects considered healthy in the control group were also resistant (4%). There was no difference for age or sex between resistant and non-resistant subjects. Comparing our findings with those reported in the literature confirmed that 3 to 5% of healthy subjects and 15 to 25% of patients with history of venous thromboembolism are resistant to activated C protein.

CONCLUSION

Resistance to activated C protein thus appears as a risk factor for thrombotic events which is comparatively more frequent than other causes of thrombotic disease.