Description of Venous Thromboembolism in Hospitalized Patients With Metastatic Cancer: A National Sample

Background: This study aimed to determine patient-, tumor-, and hospital-level characteristics associated with venous thromboembolism (VTE), and to assess the impact of VTE on in-hospital mortality and length of hospital stay in hospitalized patients with metastatic cancer. Methods: Using the Nationwide Inpatient Sample database, a cross-sectional analysis was performed of patients aged ≥18 years with at least 1 diagnosis of primary solid tumor and subsequent secondary or metastatic tumor between 2008 and 2013. Results: Among 850,570 patients with metastatic cancer, 6.6% were diagnosed with VTE. A significant trend for increasing VTE rates were observed from 2008 to 2013 (5.7%-7.2%; P<.0001). Using an adjusted multilevel hierarchical regression model, higher odds of VTE were seen among women (odds ratio [OR], 1.04; 95% CI, 1.02-1.06), black versus white patients (OR, 1.14; 95% CI, 1.11-1.18), and those with an Elixhauser comorbidity index score of ≥3 (OR, 2.50; 95% CI, 2.38-2.63). Hospital-level correlates of VTE included treatment in a teaching hospital (OR, 1.05; 95% CI, 1.01-1.11) and an urban location (OR, 1.18; 95% CI, 1.09-1.27), and admission to hospitals in the Northeast (OR, 1.16; 95% CI, 1.08-1.24) and West (OR, 1.09; 95% CI, 1.03-1.16) versus the South. Patients with metastasis to the liver, brain, or respiratory organs and those with multiple (≥2) metastatic sites had higher odds of VTE, whereas those with metastasis to lymph nodes and genital organs had lower odds. Patients diagnosed with versus without VTE had higher odds of in-hospital mortality (OR, 1.50; 95% CI, 1.38-1.63) and prolonged hospital stay (OR, 1.65; 95% CI, 1.57-1.73). Conclusions: The frequency of VTE in patients with metastatic cancer is increasing. Patient characteristics, hospital factors, and site of metastasis independently predict the occurrence of VTE and allow for better stratification of patients with cancer according to their VTE risk.