Diagnostic testing for coagulopathies in patients with ischemic stroke

Background-Hypercoagulable states are a recognized, albeit uncommon, etiolo gy of ischemic stroke. It is unclear how often the results of specialized c oagulation tests affect management. Using data compiled from a systematic r eview of available studies, we employed quantitative methodology to assess the diagnostic yield of coagulation tests for identification of coagulopath ies in ischemic stroke patients. Summary of Review-We performed a MEDLINE search to identify controlled stud ies published during 1966-1999 that reported the prevalence of deficiencies of protein C, protein S, antithrombin III, plasminogen, activated protein C resistance (APCR)/factor V Leiden mutation (FVL), anticardiolipin antibod ies (ACL), or lupus anticoagulant (LA) in patients with ischemic stroke. Th e cumulative prevalence rates (pretest probabilities) and positive likeliho od ratios for all studies and for those including only patients aged less t han or equal to 50 years were used to calculate posttest probabilities for each coagulopathy, reflecting diagnostic yield. The cumulative pretest prob abilities of coagulation defects in ischemic stroke patients are as follows : LA, 3% (8% for those aged less than or equal to 50 years); ACL, 17% (21% for those aged less than or equal to 50 years); APCR/FVL, 7% (11% for those aged less than or equal to 50 years); and prothrombin mutation, 4.5% (5.7% for those aged less than or equal to 50 years). The posttest probabilities of ACL, LA, and APCR increased with increasing pretest probability, the sp ecificity of the tests, and features of the patients' history and clinical presentation. Conclusions-The pretest probabilities of coagulation defects in ischemic st roke patients are low. The diagnostic yield of coagulation tests may be inc reased by using tests with the highest specificities and by targeting patie nts with clinical or historical features that increase pretest probability. Consideration of these data might lead to more rational ordering of tests and an associated cost savings.