Prevalence and patient profile in activated protein C resistance.

Activated protein C resistance (APC-R) is a recently defined abnormality of the coagulation system predisposing to the development of a hypercoagulable state. The authors have attempted to evaluate the prevalence and clinical manifestation of APC-R by studying a population of 183 patients with a history of venous thromboembolic episodes. Laboratory evaluation of APC-R was performed using the test initially described by Dahlbäck and colleagues based on the activated partial thromboplastin time (APTT) with the Coatest APC resistance kit (Chromogenix, Sweden) on KC10 coagulometer (Amelung, Germany). These results showed a 13% prevalence of APC-R as demonstrated by an APC ratio below 2.0. The male-to-female ratio was 1:7. Most of the thrombotic episodes were deep venous thromboses (50%).