Low Risk of Venous Thromboembolism in Hospitalized Stroke Patients

Background: Guidelines and quality performance measures recommend venous thromboembolism (VTE) prophylaxis in patients hospitalized with stroke if they have paralysis or are confined to bed and also recommend that all hospitalized medical patients have VTE risk assessment performed. The Padua Prediction Score is a validated VTE risk prediction model for medical patients based on clinical variables that are readily available at the time of admission, including the diagnosis of stroke. We sought to determine the risk of VTE in stroke patients based on Padua score and mobility status at the time of admission.

Methods: The Michigan Hospital Medicine Safety Consortium is a quality collaborative of 52 hospitals with a goal of reducing adverse events in hospitalized medical patients. From December 2011 to September 2015, trained abstractors collected data on a representative sample of patients including VTE risk variables, VTE prophylaxis received, and VTE events during hospitalization. Patients were excluded from the cohort if they were < 18 years old, admitted for VTE or comfort care, had a surgical procedure during hospitalization, directly admitted to an intensive care unit (ICU) or were prescribed anticoagulation treatment.  For this analysis, we only included patients who had active stroke on admission.  Immobility was defined as paralysis, bed rest greater than 72 hours prior to hospitalization, or immobilized by a plaster cast.  Patients were grouped based on Padua risk score and mobility status.  In-hospital VTE rates were compared using Fisher’s exact test.

Results: Out of 78,794 patients, 2,670 (3.4%) had an active stroke on admission. Of patients with stroke, 622 (23.3%) were high-risk for VTE based on Padua score and 339 (12.7%) were considered immobile. The rates of in-hospital VTE based on Padua score were 0.3% for high-risk and 0.0% for low-risk (p=0.05), and based on mobility status were 0.0% for immobile and 0.1% for mobile patients (p=0.76).  Most low risk patients based on Padua score (92%) or mobility status (78%) received VTE prophylaxis. VTE rates by type of prophylaxis are shown in Table 1 by Padua risk category and in Table 2 by mobility status.

Conclusions: Patients hospitalized with acute stroke who are not admitted to an ICU have low rates of VTE, although this observed rate may be mitigated by the use of prophylaxis.  Most patients are mobile yet receive prophylaxis, contrary to guideline recommendations. The Padua risk assessment tool appears to safely identify low risk patients for whom prophylaxis may not be required.

Table 1.  VTE Events in Patients with Acute Stroke on Hospital Admission, Grouped by Padua Score

Table 2.  VTE Events in Patients with Acute Stroke on Hospital Admission, Grouped by Mobility Status