5. Siguret V, Gouin I, Debray M, et al. Initiation of warfarin therapy in elderly medical inpatients: a safe and accurate regimen. Am J Med. 2005; 118:137-142.
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Warfarin therapy is widely used in geriatric populations. Sometimes over-anticoagulation occurs when warfarin therapy is initiated based on standard loading and maintenance dose in the hospital setting. This is mainly due to decreased hepatic clearance and polypharmacy in the geriatric population. A recent study in France demonstrated a useful and simple low-dose regimen for starting warfarin therapy (target INR: 2.0–3.0) in the elderly without over-anticoagulation. The patients enrolled in this study were typical geriatric patients with multiple comorbid conditions. These patients also received concomitant medications known to potentiate the effect of warfarin. One hundred six consecutive inpatients (age %70, mean age of 85 years) were given a 4-mg induction dose of warfarin for 3 days, and INR levels were measured on the 4th day. From this point, the daily warfarin dose was adjusted according to an algorithm (see Table 1), and INR values were obtained every 2–3 days until actual maintenance doses were determined. The maintenance dose was defined as the amount of warfarin required to yield an INR in 2.0 to 3.0 range on 2 consecutive samples obtained 48–72 hours apart in the absence of any dosage change for at least 4 days. Based on this algorithm, the predicted daily warfarin dose (3.1 ± 1.6 mg/day) correlated closely with the actual maintenance dose (3.2 ± 1.7 mg/day). The average time needed to achieve a therapeutic INR was 6.7 ± 3.3 days. None of the patients had an INR >4.0 during the induction period. This regimen also required fewer INR measurements.
Intracranial hemorrhage and gastrointestinal bleeding are serious complications of over-anticoagulation. The majority of gastrointestinal bleeding episodes respond to withholding warfarin and reversing anticoagulation. However, intracranial hemorrhage frequently leads to devastating outcomes. A recent report suggested that an age over 85 and INR of 3.5 or greater were associated with increased risk of intracranial hemorrhage. The warfarin algorithm proposed in this study provides a simple, safe, and effective tool to predict warfarin dosing in elderly hospitalized patients without over-anticoagulation. Although this regimen still needs to be validated in a large patient population in the future, it can be incorporated into computer-based dosing entry programs in the hospital setting to guide physicians in initiating warfarin therapy.
6. Wisnivesky JP, Henschke C, Balentine J, Willner, C, Deloire AM, McGinn TG. Prospective validation of a prediction model for isolating inpatients with suspected pulmonary tuberculosis. Arch Intern Med. 2005;165:453-7.
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Whether to isolate a patient for suspected pulmonary tuberculosis (TB) is often a balancing act between clinical risk assessment and optimal hospital resource utilitization. Practitioners need a relatively simple but sophisticated tool that they can use at the bedside to more precisely assess the likelihood of TB for more efficient and effective triage.
These authors previously developed such a tool with a sensitivity of 98% and specificity of 46%. (See Table 2 for details) This study was designed to validate this decision rule in a new set of patients. Patients were enrolled in 2 tertiary-care hospitals in New York City area over a 21-month period. They were all admitted and isolated because of clinical suspicion for pulmonary TB, not utilizing the decision rule under study. Study team members collected demographic, clinical risk factors, presenting symptoms, and signs, laboratory, and radiographic findings. Chest x-ray findings were reviewed by investigators who were blinded to the other clinical and demographical information. The gold standard of diagnosis was at least 1 sputum culture that was positive for Mycobacterium tuberculosis.