Comparison of outcomes after hospitalization for deep venous thrombosis or pulmonary embolism.

Venous thrombosis and pulmonary embolism are commonly viewed as different manifestations of a single disease process, venous thromboembolism. Recent evidence suggests that there may be important differences between patients who manifest these two conditions. Using linked hospital discharge records we analyzed 71,250 patients hospitalized with a principal diagnosis of venous thrombosis alone or pulmonary embolism and analyzed predictors of rehospitalization within 6 months for venous thrombosis or pulmonary embolism. There were 51233 patients diagnosed with venous thrombosis alone and 21,625 diagnosed with pulmonary embolism. Comparing patients initially diagnosed with venous thrombosis alone to patients with pulmonary embolism, the relative risk of being rehospitalized with venous thrombosis within 6 months for venous thrombosis was 2.7. Conversely, when patients with pulmonary embolism were compared to patients with venous thrombosis alone, the relative risk of rehospitalization within 6 months with a diagnosis of pulmonary embolism was 4.2. In multivariate models the strongest predictor of recurrent thromboembolism manifest as pulmonary embolism was an initial diagnosis of pulmonary embolism and the strongest predictor of recurrence as venous thrombosis was an initial diagnosis of venous thrombosis. We conclude that the initial clinical manifestation of thromboembolism strongly predicts the manifestation of a recurrence. Venous thrombosis and pulmonary embolism appear to be distinct, albeit overlapping, clinical entities with different natural histories.