Development of A Clinical Prediction Rule for Risk Stratification of Recurrent Venous Thromboembolism In Patients with Cancer-Associated Venous Thromboembolism

Abstract

475 Background: Current guidelines suggest that all cancer patients with venous thromboembolism be treated with long-term low molecular weight heparin (LMWH). However, whether treatment strategies should vary according to patient and malignancy characteristics, in particular whether patients with low risk of VTE recurrence can be identified, remains unknown. Methods: We performed a single centre retrospective cohort study conducted at the Thrombosis Unit of the Ottawa Hospital. The charts of patients with cancer and VTE followed from 2002 to 2004 and from 2007 to 2008 were reviewed to assess the feasibility of derivation of a clinical prediction rule that stratifies VTE recurrence risk in patients with cancer—associated venous thrombosis through identification and evaluation of characteristics of malignancy and other clinical characteristics. We analysed only the patients who had a recurrent VTE within the first 6 months of anticoagulation. A univariate analysis determined the strength of association between each potential predictor and VTE recurrence. All potential predictor variables (p<0.25) were evaluated in a logistic regression model. Result: Of 543 patients 55 (10.1%) presented with a VTE recurrence during the first 6 months of anticoagulation. At VTE recurrence 19 (9.5%) patients were using VKA and 36 (10.5%) patients were using LMWH. The relative risk for VTE recurrence was not significantly different between patients who used VKA or LMWH [RR= 1. 13 (95%CI, 0.743 – 1.711; p= 0.565)]. A multivariate analysis suggested that gender, primary tumour site, tumour stage and history of prior VTE were significant variables to include in the clinical prediction rule. The final model included female gender, lung cancer and prior history of VTE as increasing risk and breast cancer and stage I disease as lowering risk. Patients with a score equal or less than 0 have low risk (4.5%) for VTE recurrence and this represented 48% of our patients. Patients with a score equal or above 1 have high risk (> 19%) for VTE recurrence (Tables 1 and 2). Conclusion: We were able to derive a simple and easy scoring system that stratifies patients with cancer-associated thrombosis into low or high risk of recurrent VTE. Future prospective validation of the model is warranted and may be very relevant to better tailor anticoagulation treatment in this heterogeneous population. Disclosure: No relevant conflicts of interest to declare.

Comparison of apixaban to rivaroxaban and enoxaparin in acute cancer‐associated venous thromboembolism

“…P ‐values of <0.05 were considered to be statistically significant. To assess the risk of VTE recurrence, and compare the risk profile among study groups, we used the Ottawa prediction model …”

2019 ESC Guidelines for the diagnosis and management of acute pulmonary embolism developed in collaboration with the European Respiratory Society (ERS)

“…However, the definition of cured cancer is not always clear. The risk of recurrence of PE in cancer was assessed in a cohort study of 543 patients and was validated in an independent set of 819 patients [368]. The proposed score to predict the risk of recurrence included breast cancer (minus 1 point), Tumour Node Metastasis stage I or II (minus 1 point), and female sex, lung cancer, and previous VTE ( plus 1 point each).…”

“…The proposed score to predict the risk of recurrence included breast cancer (minus 1 point), Tumour Node Metastasis stage I or II (minus 1 point), and female sex, lung cancer, and previous VTE ( plus 1 point each). Patients with a score ⩽0 were at low risk (⩽4.5%) and those with a score ⩾1 were at high (⩾19%) risk of VTE recurrence over the first 6 months [368].…”

Acute Pulmonary Embolism after Discharge: Duration of Therapy and Follow-up Testing

“…105 In a cohort of 543 patients with cancer-associated VTE, gender, primary tumor site, cancer stage, and prior VTE resulted being independent predictors for recurrent VTE. 106 A model was derived from this cohort which includes four items (female gender, primary tumor site, tumor stage, prior VTE). Sensitivity was 100%, separation of recurrence rates was wide, negative predictive value was 98.1%, and negative likelihood ratio was 0.16 for recurrent VTE).…”