HIV infection is a risk factor for venous thromboembolism

The reported incidence of venous thromboembolism (VTE) in patients with human immunodeficiency virus (HIV) infection has ranged from 0.25 to 0.96% in clinical studies, but up to 17% at autopsy. A preliminary analysis at our hospital suggested that the frequency of VTE among HIV-positive individuals might be higher than previously reported. To further evaluate this issue, we performed a retrospective study of patients with a diagnosis of VTE and/or HIV infection discharged from our hospital between July 1, 1998 and June 30, 1999. A total of 13,496 patients were discharged during the year of the study. There were 244 patients with VTE and 362 who were HIV-positive. Ten of the 244 patients with VTE were HIV-positive (4.1%). The frequency of VTE among HIV-positive individuals was 10/362 (2.8%) compared to 234/13134 (1.8%) in the non-HIV-positive group, but the difference is not statistically significant. However, in patients under age 50, the frequencies were significantly different: 10/302 (3.31%) versus 35/6594 (0.53%), respectively (p<0.0001). The frequency of VTE in HIV-positive patients less than 50 years old (3.31%) was greater than in HIV-positive patients over 50 years of age (0/60), but the difference did not reach statistical significance. In contrast, in the non-HIV-positive group, VTE was significantly more frequent in those 50 and older compared to younger patients (3.04% versus 0.53%, p=0.0001). Statistical analysis indicated that the direction of association between age and diagnosis of VTE differed for HIV-positive patients versus non-HIV-positive patients. Our results suggest that HIV-positive patients under age 50 are at increased risk for VTE compared with non-HIV-positive individuals.