title: Acquired activated protein C resistance caused by lupus anticoagulants.
abstract: Lupus anticoagulants (LA) can cause acquired activated protein C resistance (APC-R), but the clinical significance is unclear. To investigate thrombosis and acquired APC-R in patients with LA, we enrolled all 132 patients undergoing hypercoagulability testing with positive LA results and in whom APC-R (with factor V-deficient plasma) was performed during a 2.5-year period. Among 121 patients without factor V Leiden, 24.0% had acquired APC-R; retrospective and prospective (mean follow-up, 2.0 years) thrombotic events were analyzed. The distribution of venous vs arterial thrombosis was different for APC-R vs no APC-R (P = .0064). The majority (19/29 [66%]) with acquired APC-R experienced venous thrombosis, whereas a minority experienced arterial thrombosis (9/29 [31%]; P = .017). The opposite pattern occurred among patients without APC-R (arterial thrombi more common than venous thrombi). After excluding thrombotic events more than 5 years from a positive LA test, venous thrombosis occurred in 62% with (18/29) vs 32% without (29/92) APC-R (P = .0045); and arterial thrombosis in 28% with (8/29) vs 51% without (47/92) APC-R (P = .033). Patients with acquired APC-R due to LA had more venous thrombosis than did patients with LA without APC-R and experienced venous more often than arterial thrombosis.
authors.affiliation: James Homer Wright Pathology Laboratories, Massachusetts General Hospital, Boston, 02114, USA.
authors.forename: Adam J
authors.initials: AJ
authors.lastname: Saenz
authors.forename: Nicholas V
authors.initials: NV
authors.lastname: Johnson
authors.forename: Elizabeth M
authors.initials: EM
authors.lastname: Van Cott
mesh_terms: D020016:Activated Protein C Resistance / Q000097:blood / Q000209:etiology*; D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D006801:Humans; D016682:Lupus Coagulation Inhibitor / Q000097:blood*; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D019851:Thrombophilia / Q000097:blood / Q000209:etiology*; D013927:Thrombosis / Q000097:blood / Q000209:etiology*
chemical_list: D016682:Lupus Coagulation Inhibitor