title: Acquired APC resistance in neurosurgical patients may not be a risk factor for postoperative deep vein thrombosis.
abstract: Acquired resistance to activated protein C has been reported during oral contraception and pregnancy. Its thrombogenic potential was studied in 41 neurosurgical patients who were enrolled in the placebo group of a thromboprophylaxis trial. Normalized activated protein C sensitivity ratio (nAPC-SR), clotting activity of factors V and VIII, and levels of protein C antigen were measured prior to and at days 3 and 7 after surgery. Bilateral venography was done in all patients at days 8-10 to demonstrate deep vein thrombosis. A lowered nAPC-SR was found in 76% (baseline), 80% (day 3), and 88% (day 7) of patients. It was inversely related to factor VIII clotting activity (p = .0003) and protein C antigen, (p = .02). Deep vein thrombosis was demonstrated in 30% of patients with a normal nAPC-SR and in 23% of patients with a lowered nAPC-SR. Pulmonary embolism was not observed. Multivariate analysis did not identify a lowered nAPC-SR as a thrombotic risk factor, in contrast with gender (women, p = .02) and Quetelet index (> or = 25 kg/m2, p = .006). Our data provide no evidence that acquired activated protein C resistance, frequently found in neurosurgical patients, contributes to their high risk of postoperative deep vein thrombosis.
authors.affiliation: Division of Hemostasis, Thrombosis and Rheology, University Hospital, Groningen, The Netherlands.
authors.forename: J R
authors.initials: JR
authors.lastname: Meinardi
authors.forename: C M
authors.initials: CM
authors.lastname: Henkens
authors.forename: P J
authors.initials: PJ
authors.lastname: de Kam
authors.forename: J
authors.initials: J
authors.lastname: van der Meer
mesh_terms: D020016:Activated Protein C Resistance / Q000097:blood* / Q000209:etiology; D000293:Adolescent; D000328:Adult; D000368:Aged; D000941:Antigens / Q000097:blood; D004311:Double-Blind Method; D005165:Factor V / Q000378:metabolism; D005169:Factor VIII / Q000378:metabolism; D005260:Female; D006801:Humans; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D019635:Neurosurgical Procedures / Q000009:adverse effects*; D016017:Odds Ratio; D010690:Phlebography; D010919:Placebos; D011183:Postoperative Complications / Q000097:blood*; D011486:Protein C / Q000276:immunology / Q000378:metabolism; D012044:Regression Analysis; D012189:Retrospective Studies; D012307:Risk Factors; D012737:Sex Factors; D020246:Venous Thrombosis / Q000097:blood / Q000517:prevention & control* / Q000601:surgery*
chemical_list: D000941:Antigens; D010919:Placebos; D011486:Protein C; D005165:Factor V; D005169:Factor VIII