Successful Model for Guideline Implementation to Prevent Cancer-Associated Thrombosis: Venous Thromboembolism Prevention in the Ambulatory Cancer Clinic

PURPOSE

Guidelines recommend venous thromboembolism (VTE) risk assessment in outpatients with cancer and pharmacologic thromboprophylaxis in selected patients at high risk for VTE. Although validated risk stratification tools are available, < 10% of oncologists use a risk assessment tool, and rates of VTE prophylaxis in high-risk patients are low in practice. We hypothesized that implementation of a systems-based program that uses the electronic health record (EHR) and offers personalized VTE prophylaxis recommendations would increase VTE risk assessment rates in patients initiating outpatient chemotherapy.

PATIENTS AND METHODS

Venous Thromboembolism Prevention in the Ambulatory Cancer Clinic (VTEPACC) was a multidisciplinary program implemented by nurses, oncologists, pharmacists, hematologists, advanced practice providers, and quality partners. We prospectively identified high-risk patients using the Khorana and Protecht scores (≥ 3 points) via an EHR-based risk assessment tool. Patients with a predicted high risk of VTE during treatment were offered a hematology consultation to consider VTE prophylaxis. Results of the consultation were communicated to the treating oncologist, and clinical outcomes were tracked.

RESULTS

A total of 918 outpatients with cancer initiating cancer-directed therapy were evaluated. VTE monthly education rates increased from < 5% before VTEPACC to 81.6% (standard deviation [SD], 11.9; range, 63.6%-97.7%) during the implementation phase and 94.7% (SD, 4.9; range, 82.1%-100%) for the full 2-year postimplementation phase. In the postimplementation phase, 213 patients (23.2%) were identified as being at high risk for developing a VTE. Referrals to hematology were offered to 151 patients (71%), with 141 patients (93%) being assessed and 93.8% receiving VTE prophylaxis.

CONCLUSION

VTEPACC is a successful model for guideline implementation to provide VTE risk assessment and prophylaxis to prevent cancer-associated thrombosis in outpatients. Methods applied can readily translate into practice and overcome the current implementation gaps between guidelines and clinical practice.

Venous thrombosis and cancer: from mouse models to clinical trials

Cancer patients have a ~4 fold increased risk of venous thromboembolism (VTE) compared with the general population and this is associated with significant morbidity and mortality. This review summarizes our current knowledge of VTE and cancer, from mouse models to clinical studies. Notably, the risk of VTE varies depending on the type and stage of cancer. For instance, pancreatic and brain cancer patients have a higher risk of VTE than breast and prostate cancer patients. Moreover, patients with metastatic disease have a higher risk than those with localized tumors. Tumor-derived procoagulant factors and growth factors may directly and indirectly enhance VTE. For example, increased levels of circulating tumor-derived, tissue factor-positive microvesicles may trigger VTE. In a mouse model of ovarian cancer, tumor-derived IL-6 and hepatic thrombopoietin have been linked to increased platelet production and thrombosis. In addition, mouse models of mammary and lung cancer showed that tumor-derived granulocyte colony-stimulating factor causes neutrophilia and activation of neutrophils. Activated neutrophils can release neutrophil extracellular traps (NETs) that enhance thrombosis. Cell-free DNA in the blood derived from cancer cells, NETs and treatment with cytotoxic drugs can activate the clotting cascade. These studies suggest that there are multiple mechanisms for VTE in patients with different types of cancer. Preventing and treating VTE in cancer patients is challenging; the current recommendations are to use low-molecular-weight heparin. Understanding the underlying mechanisms may allow the development of new therapies to safely prevent VTE in cancer patients.

A survey of thrombosis experts evaluating practices and opinions regarding venous thromboprophylaxis in patients with active cancer hospitalized with an acute medical illness

Background

Current clinical practice guidelines recommend the use of prophylactic doses of low molecular weight heparins for cancer patients requiring hospitalization for acute medical illness. However, a recently published meta-analysis suggested that the risk-benefit ratio of current thromboprophylaxis regimens administered to all cancer patients admitted for medical illness is unclear. We sought to assess the clinical equipoise in using thromboprophylaxis for hospitalized medically ill cancer patients.

Methods

An electronic survey was conducted. The target sample included Thrombosis experts and members of Thrombosis Canada or the VECTOR research group.

Results

The survey was distributed 54 participants. The final response rate was 67% (36/54). The majority (75%; 95% CI: 60.3 to 85%) of responders indicated that the benefits of pharmacological parenteral thromboprophylaxis outweigh the risks. However, 63.9% (95% CI: 50.6 to 77.3%) believe that there is still clinical equipoise around the use of thromboprophylaxis in this patient population, and 88.9% (95% CI: 77.3 to 95.8%) would consider participating in a randomized trial—30.6% and 58.3% in a placebo-controlled or comparison of different agents/dosing-controlled randomized trial, respectively. For participants who would consider a randomized-controlled trial comparing different doses of thromboprophylaxis agents, the MCID was 2% between the two arms. The most common drug to be compared was enoxaparin (26%), and the two suggested doses were 30 mg and 40 mg SC twice daily.

Conclusions

Our clinical survey of thrombosis experts confirms that there is equipoise regarding the use of current regimens of parenteral pharmacological thromboprophylaxis in medically ill cancer patients. A majority of physicians would participate in a randomized-controlled trial comparing different dose of LMWH. The MCID in the risk of VTE identified was 2%.