Is an outpatient Anticoagulation Service safe and effective for monitoring patients on warfarin therapy?
An outpatient anticoagulation service provides safe monitoring of warfarin therapy, with major bleeding primarily linked to underlying anatomic risks rather than age or concurrent medications.
In 66 months, a general hospital's outpatient Anticoagulation Service (ACS) monitored 263 patients who received 280 courses of warfarin sodium totalling 254 patient treatment years. Major hemorrhagic morbidity was 4% of courses and there was no mortality attributable to warfarin therapy. Major hemorrhage occurred in patients with increased anatomic risk of bleeding (diverticulosis, hemorrhoids, cystitis), and was not a function of patient age, sex, anticoagulation control, or medications administered concurrently with warfarin. Control of anticoagulation was not correlated with age or other medications, but was worsened significantly by the presence of congestive heart failure. We attribute a favorable experience with outpatient ACS to careful patient selection, patient education and monitoring, attention to duration of anticoagulation, and continuing communication with primary physicians who retained responsibility for medical care. An ACS offers safety, consistency, efficiency, and a unified approach to outpatient anticoagulation in the general hospital setting.
Faith B. Davis (1977) studied this question.