Existing Warfarin Therapy in Long-Term Care Facilities Maybe Inadequate.

Despite evidence-based guidelines derived from large clinical trials supporting the use of warfarin for stroke prophylaxis, studies in elderly patients have shown that oral anticoagulants are not used optimally. The risk associated with inappropriate use is compounded by the observation that the elderly are at enhanced risk of thromboembolic complications compared with younger atrial fibrillation patients. All patients with atrial fibrillation who do not have a contraindication to warfarin, and who meet inclusion criteria, should be treated with warfarin to achieve a target International Normalized Range (INR) of 2.5 (range 2.0–3.0). INR levels of 2.0–3.0 have been shown to be relatively safe and more efficacious than lower target INR values in all age groups including the elderly. Patients with INR values below this range remain at increased risk of thrombosis, while those with INR values above the given range are at increased risk of bleeding. The primary objective of this study was to determine the achieved intensity of warfarin therapy in a cohort of patients living at long-term care facility. In such facilities optimal anticoagulation should be achievable, since laboratory monitoring, dose adjustment, and compliance can be achieved. In this study, data were collected on physicians’ warfarin prescribing practices as well as INR levels of 108 residents in five long-term care facilities in the Hamilton-Wentworth area over a period of 12 months. In total, 3146 INR values, extending over 28,256 patient-days of monitoring, were analyzed. Indications for warfarin were atrial fibrillation, transient ischemic attack, pulmonary embolus, cardiac valve replacement, myocardial infarction, and deep vein thrombosis. In general, the warfarin dosage was not determined using an established dosing algorithm. Our findings revealed that LTC residents spent approximately 40 percent of the time with INR values below 2.0. We therefore conclude, that the overall quality of anticoagulant therapy in long-term care patients may be inadequate. Our observations suggest that organized dosing algorithms may be of benefit in such settings, however this hypothesis needs to be confirmed in prospective studies. For this purpose we plan to implement a warfarin dosing algorithm in order to determine whether the percentage of time spent within the therapeutic INR range can be improved.