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Incidence of Venous Thromboembolism in Patients with Peripheral Arterial Disease after Endovascular Intervention
Daniel G Kindell, Emilie G Duchesneau, Sydney E Browder, Deanna Caruso, Nathan T. Shenkute, Kathleen Marulanda, William Marston, Katharine McGinigle
University of North Carolina Hospitals, Chapel Hill, NC

BACKGROUND: Venous thromboembolism (VTE) is a well-known post-surgical complication, and the estimated rate of VTE after lower extremity bypass is 1.5% at 30 days. Due to its minimally invasive nature, there is less focus on VTE after peripheral endovascular intervention (PVI) for peripheral artery disease; however, these patients often have limited mobility and there is an inflammatory reaction in the treatment area. Considering these risk factors, our objective was to describe the short-term incidence of VTE status post PVI, identify differences in sex, and examine peri-procedural antiplatelet and anticoagulation regimens. METHODS: We identified adults (age 66+) who underwent PVI between January 1, 2008-September 30, 2015 in Medicare claims data. Patients were followed 90 days from the date of procedure. VTE events during follow-up were identified using ICD-9 diagnosis codes. Covariate-standardized 30- and 90-day cumulative incidence of VTE events, overall and by sex, were estimated using Aalen-Johansen estimators accounting for death as a competing risk. Differences in sex between females and males were identified using Gray's test. Any antiplatelet or anticoagulant prescription fill was defined as any fill from 14 days prior to the endovascular intervention through the date of the VTE event. Persistence on antiplatelet and anticoagulant therapy was assessed by creating daily logs of antiplatelet and anticoagulant coverage based on dispensing dates and supply. Persistent use was defined as at least 75% of days covered during the follow-up window. Over the counter medications, namely aspirin, were not evaluated.
RESULTS: We identified 31,593 qualifying patients with a mean age of 76.8 (SD 7.4) years. Forty-six percent were male and 12% had a history of VTE. Post-procedure, DVT was a commonly diagnosed complication: 3.8% and 4.8%, at 30- and 90-days, respectively. Cumulative incidence of pulmonary embolism was 0.9% and 1.2% at 30- and 90-days post procedure, respectively (Table 1). Throughout the 90-day post procedure period females had a slightly increased risk of DVT compared to males (30-day RD 0.007, p-value <0.01; 90-day RD 0.008, p-value 0.02). There was no sex-based difference in risk of pulmonary embolism. Among patients who developed VTE, 970 (55%), had no prescription fill for antiplatelet or anticoagulation therapy (Table 2). Assuming all patients were taking aspirin, only 15% of patients who developed VTE were taking prescribed dual-antiplatelet medication persistently after PVI. After PVI, but before VTE diagnosis, 12% of patients with VTE were regularly filling anticoagulant prescriptions. CONCLUSIONS: Our cohort demonstrates the incidence of VTE after PVI is markedly higher than estimates for open surgical bypass, with increased risk of DVT among females. Future studies should aim to characterize variables associated with an increased risk of post-intervention VTE and identify strategies to increase dual antiplatelet therapy or anticoagulant prescription adherence to reduce the risk of this complication.

Table 1. VTE outcomes for Medicare beneficiaries undergoing endovascular intervention
Females (n= 17,115)Males (n= 14,478)
Outcome# eventsRisk95% CI# eventsRisk95% CIRisk Differencep-value
30 Day
DVT7300.049(0.05, 0.05)4690.042(0.04, 0.05)0.007<0.01
PE1650.011(0.01, 0.01)1210.012(0.01, 0.01)-0.0010.68
Death1,0940.078(0.07, 0.08)8090.079(0.07, 0.09)-0.0010.70
90 Day
DVT9250.065(0.06, 0.07)5880.057(0.05, 0.06)0.0080.02
PE2180.015(0.01, 0.02)1600.016(0.01, 0.02)-0.0010.69
Death2,1810.174(0.17, 0.18)1,7100.187(0.18, 0.20)-0.00130.03

Table 2. Prescription antiplatelet and anticoagulant use among individuals with VTE
Overall (n= 1,764)Females(n= 1,072)Males (n= 692)
Any fill,n (%)
Antiplatelet459 (26.0)285 (26.6)174 (25.1)
Anticoagulant490 (27.8)275 (25.7)215 (31.1)
Antiplatelet + anticoagulant155 (8.8)91 (8.5)64 (9.2)
Neither970 (55.0)603 (56.3)367 (53.0)
Persistent use,n (%)
Antiplatelet269 (15.2)155 (17.5)89 (15.8)
Anticoagulant215 (12.2)102 (11.5)88 (15.6)
Antiplatelet + anticoagulant39 (2.2)22 (2.1)17 (2.5)

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