Predictors Of Vena Cava Filter Use For Venous Thromboembolism In Cancer Patients

The use of vena cava filters (VCF) in the treatment of venous thromboembolism (VTE) is controversial. Few studies have evaluated the use of VCFs in cancer patients with acute thrombosis.

To determine frequency of VCF placement and factors associated with VCF use in patients with cancer hospitalized for acute VTE, and to compare these findings to patients without cancer hospitalized for acute VTE.

Using a retrospective observational study design, we analyzed hospital discharge records in California from 2005-2009 of cases presenting with acute VTE. Patients with cancer were identified by specific ICD-9-CM codes for the index VTE admission or a cancer diagnosis within 6 months prior to the index VTE. Bivariate and multivariable logistic regression analyses were used to determine predictive factors for placement of a VCF in cancer patients. Candidate risk factors included basic demographic parameters, cancer type, severity-of-illness (SOI) on admission, undergoing surgery, bleeding, and hospital characteristics.

A VCF was placed in 19.6% of 14,000 cancer cases admitted with a principal diagnosis of acute VTE, versus 10.8% of 70,472 non-cancer cases admitted during the same time period. Among cancer cases, there was little variation in percentage that received a VCF based on age, and no significant variation across race or insurance type, except that self pay cancer patients had a lower rate of VCF placement. Variation across hospitals in the percentage of cancer cases that received a VCF was striking, ranging from 0% to 52% among hospitals that admitted a minimum of 15 acute VTE cases. There was a strong correlation (r=0.72, R²=0.52) in the frequency of VCF placement in cancer and non-cancer cases within individual hospitals. Among cancer types, the frequency of VCF placement was highest in cases with brain cancer (43%), with the observed frequency of VCF use among other cancer types ranging from 8%-23%. Patients with brain cancers, which has a high perceived bleeding risk were over 4 fold more likely to have a VCF placed compared to those cancers with low bleeding risk. Having acute leukemia did not predict for VCF placement. Only 8.2% of cancer patients had a strict contraindication to anticoagulation (acute bleeding or recent/imminent surgery), which are the only guideline-based indications for VCF placement. Active bleeding and undergoing surgery were each strongly associated with VCF use: 47% of cases that bled and 58% of cases who underwent surgery had a VCF placed. Results of the multivariable logistic model are shown in the table. In addition to bleeding and undergoing surgery, factors associated with VCF insertion included: larger hospital, urban location, private hospital and greater SOI at the time of admission.

The frequency of VCF use in cancer patients admitted for acute VTE is much higher than in non-cancer patients. Major risk factors for VCF use include bleeding, undergoing recent surgery, having brain cancer, urban location, and greater severity of illness. The frequency of VCF placement among cancer patients varied widely across hospitals. Given the extraordinary variation in the frequency of use of VCFs between hospitals, more research is needed to better define outcomes of VCF placement in cancer patients.

Ho: American Society of Hematology: ASH HONORS trainee research award Other.