Finding a rIsk assessmeNt moDel for thromboembolic events in hospItalized Cancer pATiEnts: the INDICATE study running title: thromboembolism in hospitalized cancer patients

Background: Hospitalized cancer patients are at increased risk for Thromboembolic Events (TEs). As untailored thromboprophylaxis is associated with hemorrhagic complications, the definition of a risk-assessment model (RAM) in this population is needed. Objectives: INDICATE was an observational study enrolling hospitalized cancer patients, with the primary objective of assessing the Negative Predictive Value (NPV) for TEs during hospitalization and within 45 days from discharge of low-grade Khorana Score (KS=0). Secondary objectives were to assess KS Positive Predictive Value (PPV), the impact of TEs on survival and the development of a new RAM. Materials and Methods: Assuming 7% of TEs in KS=0 patients as unsatisfactory percentage and 3% of as satisfactory, 149 patients were needed to detect the favorable NPV with one-sided a= 0.10 and power=0.80. Stepwise logistic regression was adopted to identify variables included in a new RAM.Results: Among 535 enrolled patients, 153 (28.6%) had a KS=0. The primary study objective was met: 29 (5.4%) TEs were diagnosed, with 7 (4.6%) cases in the KS=0 group (NPV=95.4%, 95%CI: 90.8-98.1%; one-sided p=0.084). However, the PPV was low (5.7%, 95%CI: 1.9-12.8%); a new RAM based on albumin (OR 0.34, p=0.003), log(LDH) (OR 1.89, p=0.023) and presence of vascular compression (OR 5.32, p<.001) was developed and internally validated. Also, TEs were associated with poorer OS (median, 5.7 vs 24.8 months, p <.001).Conclusion: INDICATE showed that the KS has a good NPV but poor PPV for TEs in hospitalized cancer patients. A new RAM was developed, and deserves further assessment in external cohorts.