Abstract
HIV-infected patients are at high risk for venous and arterial thrombosis. We hypothesized that advancing stages of HIV are associated with thrombophilic abnormalities that could predispose to thrombosis. A total of 109 consecutive HIV infected patients were included in the study and twice screened for currently known thrombophilic defects with a time interval of at least 3 months. Ten percent of HIV infected patients had confirmed decreased protein C levels (< 65 IU/dL), 41% had confirmed elevated factor VIII levels (> 150 IU/dL), 22% had confirmed high fibrinogen levels (> 3.5 g/L) and 60% had a confirmed free protein S deficiency (< 65 IU/dL). Median factor VIII levels were higher in patients with AIDS defining illness compared to non AIDS defining illness (226 IU/dL versus 149 IU/dL; P< 0.001), while median free protein S levels were lower in these subgroups (45 IU/dL, versus 58 IU/dL; P< 0.001). Advancing HIV, stratified by CD4 levels of > 500 cells/μL, 200–500 cells/μL or < 500 cells/μL, respectively, was associated with increasing factor VIII levels, fibrinogen levels and decreasing free protein S levels (Figure 1). When factor VIII levels were < 100 IU/dL, median fibrinogen levels were 2.4 g/L, which was 0.3 g/L lower than when factor VIII levels were 100–150 IU/dL (P=0.033) and 0.9 g/L lower than when factor VIII levels were > 150 IU/dL (P< 0.001). Free protein S levels were 70 IU/dL when factor VIII levels were < 100 IU/dL, which decreased to 60 IU/dL when factor VIII levels were 100–150 IU/dL (P=0.010) and to 52 IU/dL when factor VIII levels were > 150 IU/dL (P< 0.001). We conclude that HIV infected patients have multiple prolonged thrombophilic abnormalities compared to the normal population, which increase with advancing HIV disease, thus providing a biologic mechanism for the increased prevalence of venous and arterial thrombosis in HIV.
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