Risk Assessment and Anticoagulation in Atrial Fibrillation in the Elderly: Malpractice or Accuracy?
To the Editor:
We read with interest the paper by Kalra et al recently published in Stroke.1 We would like to contribute to this topic with our experience in 97 patients newly admitted to our Acute Care for the Elderly Medical Unit selected for chronic or recent-onset atrial fibrillation. Seventeen patients had atrial fibrillation of recent onset (>48 hours and <6 months), and the remaining patients had chronic atrial fibrillation (>6 months). By strictly following the recommendations of the most commonly cited trials,2 3 all patients potentially needed anticoagulation to prevent thromboembolic strokes. On the contrary, although our hospital guidelines indicate the use of warfarin, the retrospective analysis of our charts revealed that 21 patients (21.6%) had neither anticoagulation nor aspirin, 49 (50.6%) had only aspirin, and 27 had only warfarin (27.8%). Of 21 patients who received neither warfarin nor aspirin, 4 had a diagnosis of active peptic ulcer, 3 severe liver cirrhosis, 3 gastric cancer, 3 cachexia, 3 anemia secondary to gastrointestinal bleeding, 2 multiple myeloma, 1 lung cancer, 1 ovarian cancer with lung metastasis, and 1 hepatocellular carcinoma. Among the remaining 76 patients, factors associated with aspirin treatment (in 49 patients) were age, cognitive impairment, functional impairment in basic activities of daily living, APACHE score, chronic obstructive pulmonary disease, and liver diseases; independently, factors were living alone, being female, number of somatic diseases, mood depression, and impairment in ≥3 instrumental activities of daily living.
These data indicate that many different factors have been barriers to warfarin prescription, but they are not based on clinical criteria alone; in fact, functional, psychological, and social factors in addition to strictly clinical factors influence the use of anticoagulation. It is indeed intuitive that people affected by terminal diseases or by pathologies involving bleeding problems are not treatable with warfarin and that persons living alone or with a cognitive or functional impairment are seriously disadvantaged in carrying out the periodic laboratory procedures related to anticoagulant prescriptions.
Warfarin therapy is logistically difficult, requiring frequent visits for blood sampling, communication, and dose adjustment, all of which are more difficult for elderly people. We suggest that before starting warfarin therapy it is necessary to assess the realistic possibility of patients performing the treatment at home. Evidence-based medicine founded on epidemiological data must be mediated in clinical practice by an accurate and ecological analysis of the living conditions of the patients.
Along this line, we emphasize the need for a better knowledge of the most important events modulating the treatment with warfarin, in particular those factors predicting major adverse effects. This is not “ageism” but good clinical practice. Meanwhile, a complete geriatric evaluation to assess conditions potentially related to the adverse effects of anticoagulants remains the most highly recommended practice in the elderly.
- Copyright © 1999 by American Heart Association
Kalra L, Perez I, Melbourn A. Risk assessment and anticoagulation for primary stroke prevention in atrial fibrillation. Stroke. 1999;30:1218–1222.
Atrial Fibrillation Investigators; Atrial Fibrillation, Aspirin, Anticoagulation Study; Boston Area Anticoagulation Trial for Atrial Fibrillation Study; Canadian Atrial Fibrillation Anticoagulation Study; Stroke Prevention in Atrial Fibrillation Study; Veterans Affairs Stroke Prevention in Nonrheumatic Atrial Fibrillation Study. Risk factors for stroke and efficacy of antithrombotic therapy in atrial fibrillation: analysis of pooled data from five randomized controlled trials. Arch Intern Med. 1994;154:1499–1457.
The correspondents present the findings of an audit in acutely ill elderly patients admitted to the hospital, which is a significantly different group of patients from the one included in our study. It is likely that these patients were medically unstable and had significantly higher comorbidity and greater functional disability compared with those presenting to general medical outpatients facilities, as included in our study. It is also unlikely that all these patients would have been considered eligible for anticoagulation, even if the recommendations of the most commonly cited trials were followed. For example, patients with known bleeding complications, severe systemic disease (including terminal disease), severe cognitive impairment, falls, and problems with warfarin administration, monitoring, or compliance were excluded from all the quoted studies, and the existence of any one of these characteristics was considered to be a contraindication to anticoagulation.
The importance of the ability to comply with anticoagulation therapy (including monitoring) is inherent in all recommendations for warfarin use and was central to our study published in Stroke. The study provided objective evidence of significant underuse of anticoagulation therapy in elderly people with atrial fibrillation at high risk of stroke who had no contraindications to anticoagulant therapy, including those of compliance and monitoring. Although we accept that a higher proportion of elderly people will have contraindications to warfarin use, we fear that nonclinical considerations should not become an excuse for excluding a large proportion of patients at higher risk from a proven effective treatment for stroke prevention. However, we acknowledge that the clinical effectiveness of anticoagulation in preventing stroke in elderly patients remains equivocal because less than 20% of the patients included in the effectiveness studies were over 75 years of age. Equally, it is not known whether the benefits seen in controlled trials in highly selected and carefully monitored patients will be replicated in mainstream care, where patients are likely to be older and anticoagulation control less rigorous than under trial conditions. The answer to these questions will determine the effectiveness of anticoagulation in preventing strokes in clinical practice as opposed to its proven efficacy in controlled trials in patients with atrial fibrillation.