Predictors of Recurrence After Deep Vein Thrombosis and Pulmonary Embolism

Abstract

RECURRENT VENOUS thromboembolism (VTE) is an important risk factor for death after pulmonary embolism (PE)^1,2 and for venous stasis syndrome after deep vein thrombosis (DVT),² and is associated with significantly increased long-term health care costs.³ While anticoagulation therapy is effective in preventing recurrence,^4,5 the optimal duration of anticoagulation after an initial episode of DVT or PE is uncertain⁶ and depends largely on the rate of recurrence. However, the reported rates of recurrent VTE vary widely, ranging from 0.6% to 5% at 90 days and from 13% to 25% at 5 years.^2,7-14 Several factors may account for the variability in reported recurrence rates. For example, studies that identified cases from acute-care hospital discharge data^8,9 or Medicare claims diagnoses¹¹ are limited by diagnostic uncertainty or misclassification, as well as failure to include autopsy-discovered recurrence or to accurately separate initial from recurrent events.¹² Moreover, studies that identified cases solely from acute-care hospital admissions may have missed recurrent VTE among patients residing in nursing homes or other long-term care facilities^9,11,12 as well as rapidly fatal recurrences occurring out of hospital.⁸ Follow-up studies of selected VTE populations, such as elderly patients,¹¹ patients referred to tertiary care centers for diagnostic evaluation and treatment,^2,15 or patients enrolled in clinical trials^{1,7,10,13,14,16} may not estimate the true recurrence rate accurately since these studies did not include the full spectrum of VTE disease. Moreover, information regarding long-term recurrence is limited since follow-up in most studies was restricted to 1 to 3 years,^1,9,11 with only 2 studies reporting follow-up to 8 years.^2,12