Use of specialized coagulation testing in the evaluation of patients with acute ischemic stroke

OBJECTIVE: To investigate the use and appropriateness of specialized coagulation tests in the evaluation of patients with acute ischemic stroke and identify factors that influence test ordering. BACKGROUND: Coagulation abnormalities are a rare but recognized cause of ischemic stroke. METHODS: Patient demographics, stroke risk factors, history of venous thrombosis or miscarriage, family history of stroke, and the results of specialized tests for coagulation disorders were recorded for a consecutive series of ischemic stroke patients over age 18 admitted to an academic medical center over 3 years (n = 674). Factors associated with testing were identified with univariate analyses in a random sample of two-thirds of the patients (n = 450). Multivariate logistic regression modeling was then used to identify variables independently associated with testing and then validated in the remaining patients (n = 224). RESULTS: Of the 31% of patients (n = 208) tested for coagulopathies, 29% (n = 60) were tested when the result was unlikely to influence therapeutic decisions. Historical factors associated with an increased incidence of a coagulopathy, such as history of venous thrombosis or miscarriage, were not commonly documented. The absence of small-artery atherosclerosis (OR 0.36, 95% CI 0.17 to 0.76) and younger age (OR 0.89 per year, 95% CI 0.87 to 0.92) were independently related to the frequency of specialized coagulation testing. CONCLUSIONS: One-third of specialized coagulation tests were ordered when the test results were unlikely to affect therapeutic decisions. Age was the only clinical factor increasing the likelihood of a coagulopathy that appeared to influence ordering of specialized coagulation tests.