Background: There are few data on the long-term risk of venous thromboembolism (VTE) among stroke survivors. We aimed to compare the incidence of VTE amongst patients with ischemic stroke versus those with intracerebral hemorrhage (ICH).
Methods: We identified all adults discharged from nonfederal acute care hospitals in CA, NY, and FL between 2005 and 2012 with previously validated ICD-9-CM codes for ischemic stroke and ICH. Our primary outcome of VTE was defined as pulmonary embolism or deep vein thrombosis. To capture incident cases of VTE, we excluded patients with a VTE prior to or during the index stroke. Kaplan-Meier survival statistics were used to calculate the cumulative rate of incident VTE. Cox regression was used to compare the risk of VTE after stroke while adjusting for demographics, vascular risk factors, and Elixhauser comorbidity index. As there was a violation of the proportional-hazards assumption, we calculated separate hazard ratios (HR) for each year of follow-up.
Results: We identified 834,660 patients with stroke, of whom 712,440 (85.3%) had ischemic stroke and 112,220 (14.7%) had ICH. Over a mean follow-up of 2.8 (+/-2.4) years, 19,937 (2.4%) developed VTE. After 7 years, the cumulative rate of VTE was 4.7% (95% confidence interval [CI], 4.5-4.9%) in patients with ICH and 4.4% (95% CI, 4.3-4.5%) in patients with ischemic stroke. In multivariable analysis, VTE risk was higher in the first year after ICH compared to ischemic stroke (HR 1.51; 95% CI, 1.43-1.58). However, following the first year, the hazard of VTE was higher among patients with ischemic stroke versus those with ICH (Figure).
Conclusions: The risk of VTE after stroke varies by stroke type and time. Patients with ICH have a higher risk of VTE in the first year after stroke as compared to those with ischemic stroke while patients with ischemic stroke have a higher risk beyond 1 year.