Characterization of thrombosis risk in ambulatory patients with cancer: results of the observational, prospective, multicenter CARTAGO study

Venous thromboembolism (VTE) is one of the leading causes of death in patients with cancer. Currently, there is a need to develop an easily applicable risk model that can identify patients who will benefit from receiving primary thromboprophylaxis to reduce the incidence of VTE. This was a non-interventional, multicenter, observational, prospective study carried out in 62 Oncology and Hematology services in Spain and Portugal between January 2018 and December 2019. The main objective of the CARTAGO study was to develop a predictive model within a competitive risk framework to assess the risk of VTE in patients with cancer undergoing chemotherapy, biological, or hormonal treatment. A total of 1596 patients were analyzed. VTE events occurred in 124 (8%) during the 6-month follow-up period (42% of deep vein thrombosis [DVT], 48% of pulmonary embolism [PE], and 10% of both DVT and PE). Four variables were selected for the multivariate predictive model to determine the risk of VTE (tumor type, D-dimer, compression of a vessel by the tumor, and leukocyte count). The 4 variables were associated with an increased risk of VTE (C-statistic, 0.646 [95%CI, 0.620-0.673]). The most significant variables in the internal validation with bootstrapping were the "very high risk" tumors (hazard ratio [HR] 2.032; 95%CI, 1.287-3.211). The CARTAGO model predicts the VTE risk in patients with cancer receiving anticancer therapy in an outpatient setting. This model can easily aid in identifying ambulatory patients who would probably benefit from primary thromboprophylaxis.