Venous thromboembolism among HIV-positive patients and anticoagulation clinic outcomes integrated within the HIV primary care setting

Abstract

The purpose of this study was to explore factors associated with venous thromboembolism (VTE) among a cohort of HIV-infected patients and to describe early outcomes of warfarin anticoagulation therapy treated in a pharmacist-based anticoagulation clinic (ACC). A nested case-control study was conducted using the University of Alabama at Birmingham 1917 HIV Clinic Cohort. Conditional logistic regression was used to estimate factors associated with VTE. Among HIV-infected VTE cases, ACC-managed patients were compared to primary care provider (PCP)-managed patients to determine Time within Therapeutic INR Range (TTR). CD4 < 200 cells/µl (OR = 4.50; 95% CI = 1.52, 13.37; p = 0.007) and prior surgical procedures (13.20; 1.56; 111.4; p = 0.018) demonstrated positive associations with VTE, whereas longer HIV duration demonstrated a negative association (0.87; 0.78, 0.98; p = 0.019). TTR was 56.2% among ACC-managed patients compared to 30.5% of PCP-managed patients (p = 0.174). Overall, prior surgical procedures and low CD4 count were associated with an increased risk of VTE among HIV-infected patients. Despite small sample size, patients managed in ACC tend to achieve greater proportion of TTR compared to those managed by PCPs, suggesting that this model of therapy may provide additional benefits to HIV-infected patients.

Elevated Risk of Venous Thromboembolism in People Living with HIV

“…At present, scholars have nearly reached a consensus that active HIV viral load and CD4 cell counts have a clear association with the progression of VTE among PWH despite the absence of consistent results in few studies [ 51 ]. According to the current retrospective cohort studies [ 17 , 18 , 20 , 52 ], as independent risk factors, CD4 counts <200 cells/µL and viral load >100,000 copies/mL exhibited positive association with the risk of a VTE. Specifically, the earlier the time of HIV diagnosis, the higher the overall effect of CD4 cell count was on the risk of a venous thrombotic event, while a negative association was found in those with prolonged HIV duration [ 52 ], which was associated with the prolonged duration of HIV viremia and/or delay in ART initiation and the nadir CD4 cell count as well [ 53 ].…”

“…According to the current retrospective cohort studies [ 17 , 18 , 20 , 52 ], as independent risk factors, CD4 counts <200 cells/µL and viral load >100,000 copies/mL exhibited positive association with the risk of a VTE. Specifically, the earlier the time of HIV diagnosis, the higher the overall effect of CD4 cell count was on the risk of a venous thrombotic event, while a negative association was found in those with prolonged HIV duration [ 52 ], which was associated with the prolonged duration of HIV viremia and/or delay in ART initiation and the nadir CD4 cell count as well [ 53 ]. The association between low CD4 cell counts and VTE have been reported to be correlated with an increasing hypercoagulable state, which was found within progressive immune suppression during HIV infection as well as high HIV viral loads [ 20 , 26 ].…”

Venous Thromboembolism Among People With HIV: Design, Implementation, and Findings of a Centralized Adjudication System in Clinical Care Sites Across the United States

“…[26][27][28] Many previous VTE studies among PWH were case reports, small case series, or otherwise limited by small numbers of outcomes. [29][30][31][32][33][34][35][36][37][38][39][40][41][42] Some have not included PEs 33,43 or DVTs 25,44 or were unable to examine differences between PEs and DVTs because of size. 34 Most were conducted before ART or before currently used agents such as integrase inhibitors were common.…”

“…[29][30][31][32][33][34][35][36][37][38][39][40][41][42] Some have not included PEs 33,43 or DVTs 25,44 or were unable to examine differences between PEs and DVTs because of size. 34 Most were conducted before ART or before currently used agents such as integrase inhibitors were common. 14,15,[36][37][38][39][40][41][45][46][47][48] Finally, VTE studies require clearly defined endpoints and accurate identification of events.…”

“…45,49,50 Medical record review and verification to minimize misclassification have been rare in previous VTE studies among PWH. 34,40,45 A call has been made for multisite HIV cohort studies to characterize VTE risks 34 and thereby improve approaches to prevention and treatment. We therefore implemented a robust verification process with centralized VTE ascertainment and adjudication in the Centers for AIDS Research Network of Integrated Clinical Systems [CFAR Network of Integrated Clinical Systems (CNICS)] cohort.…”