The Cumulative Incidence and Risk Factors of Recurrent Venous Thromboembolism in the Elderly

Background: Incidence and outcomes of recurrent venous thromboembolism (VTE) in the elderly are still not fully elucidated. The purpose of this study was to determine the incidence and identify the risk factors of VTE recurrence in this population. Methods: A prospective cohort study of a one-year follow-up of 277 patients aged >= 65 years with primary VTE was performed at King Abdulaziz Medical City, a tertiary care teaching hospital in Riyadh, Saudi Arabia. Demographic data, risk factors, and the consequences of VTE (recurrence, bleeding, and mortality) were recorded. Results: Of the 277 VTE patients, 39 (14%) were diagnosed with recurrent VTE over a median follow-up period of 12 months. The cumulative incidence of recurrent VTE was 12.75 per hundred patient-year (95% CI, 8.24-17.36). In multivariate Cox regression, malignancy (hazard ratio [HR], 2.87, 95% CI, 1.32-6.24, p=0.008) and surgery (HR 2.78, 95% CI, 1.36-5.67, p=0.005) were identified as independent risk factors for recurrent VTE. Metformin had a significant independent protection effect (HR, 0.16, 95% CI, 0.08-0.33, p<0.001). During follow-up, two patients in the recurrent VTE group and five patients in the group with no recurrent VTE, all of whom were minor bleeding cases, reported no major bleeding. Seven (18%) patients in the recurrent VTE group and nine (4%) patients in the group with no recurrent VTE died (p<0.001). Conclusion: The findings of this study show that elderly patients with initial VTE have a recurrent rate (14%), with a cumulative incidence rate of 12.75 per hundred patient-year. Malignancy and surgery were the most important clinical risk factors to impact significantly the development of recurrent VTE in our elderly population. Metformin may have a protective effect against recurrent VTE in the elderly population, and a larger study is needed to validate our findings.