Benefits, morbidity, and mortality associated with long-term administration of oral anticoagulant therapy to patients with peripheral arterial bypass procedures: a prospective randomized study.
BACKGROUND
The benefits of the long-term administration of oral anticoagulant therapy remain unclear in patients with lower extremity arterial bypass surgery. We studied the effect of warfarin plus aspirin therapy (WASA) versus aspirin therapy alone (ASA) on patient mortality, morbidity and bypass patency rates in a randomized clinical trial.


METHODS
In a multicenter, prospective, nonmasked clinical trial, 831 patients who underwent peripheral arterial bypass surgery were compared in a long-term treatment program of WASA (target international normalized ratio of 1.4 to 2.8; 325 mg/day) with ASA (325 mg/day). The primary end point was bypass patency, and mortality and morbidity were the secondary endpoints.


RESULTS
There were 133 deaths in the WASA group (31.8%) and 95 deaths in the ASA group (23.0%; risk ratio, 1.41; 95% confidence interval, 1.09 to 1.84; P =.0001). Major hemorrhagic events occurred more frequently in the WASA group (WASA, n = 35; ASA, n = 15; P =.02). In the prosthetic bypass group, there was no significant difference in patency rate in the 8-mm bypass subgroup, but there was a significant difference in patency rate in the 6-mm bypass subgroup (femoral-popliteal; 71.4% in the WASA group versus 57.9% in the ASA group; P =.02). In the vein bypass group, patency rate was unaffected (75.3% in the WASA group versus 74.9% in the ASA group).


CONCLUSIONS
The long-term administration of warfarin therapy when combined with aspirin therapy has only a few selected indications for improvement of bypass patency and is associated with an increased risk of morbidity and mortality.
Johnson
Willard C
WC
Boston VA Medical Center and Boston University School of Medicine, Mass., USA.
Williford
William O
WO
D000284:Administration, Oral; D000368:Aged; D000925:Anticoagulants / Q000627:therapeutic use*; D001241:Aspirin / Q000627:therapeutic use; D001807:Blood Vessel Prosthesis; D001900:Boston / Q000453:epidemiology; D003131:Combined Modality Therapy; D004305:Dose-Response Relationship, Drug; D004359:Drug Therapy, Combination; D005121:Extremities / Q000098:blood supply* / Q000601:surgery*; D005263:Femoral Artery / Q000601:surgery; D005500:Follow-Up Studies; D006470:Hemorrhage / Q000139:chemically induced / Q000401:mortality; D006801:Humans; D019934:International Normalized Ratio; D008396:Maryland / Q000453:epidemiology; D008875:Middle Aged; D009017:Morbidity; D016491:Peripheral Vascular Diseases / Q000150:complications / Q000401:mortality* / Q000628:therapy*; D011150:Popliteal Artery / Q000601:surgery; D011183:Postoperative Complications / Q000209:etiology / Q000401:mortality; D011446:Prospective Studies; D013995:Time; D016896:Treatment Outcome; D014654:Vascular Patency / Q000187:drug effects / Q000502:physiology; D014656:Vascular Surgical Procedures / Q000295:instrumentation / Q000401:mortality*; D014859:Warfarin / Q000627:therapeutic use
D000925:Anticoagulants; D014859:Warfarin; D001241:Aspirin