Warfarin usage in octogenarians: report from a long-term care anticoagulation service with point of care INR testing & community pharmacists

Excerpt

Background The need for oral anticoagulation has increased, including octogenarians. Upon request, the London Drugs Anticoagulation Service (AS) expanded its warfarin dosing service with certified community pharmacists and point of care INR testing into long-term care (LTC). Purpose To evaluate the AS in LTC octogenarian residents. Methods LTC residents age ≥80 years who were referred to the AS between 2005 and 2007 were randomly selected for retrospective chart review. Results Twelve charts were reviewed with 92% females and 8% males; a mean age of 85.7 years; a mean weight 69.1 kg; a mean of 12 medications; and a mean AS duration of 13.4 months. Medical histories showed all patients had cardiac conditions; 33.3% with stroke; and 5 patients (41.7%) with cancer. Warfarin was prescribed for atrial fibrillation (75.0%), DVT prophylaxis (17.7%) and pulmonary embolism (8.3%); with a target INR 2.0–3.0 (100%); a mean dose of 22.9 mg/week (range 3.5–49.0); a mean of 22.5 dosage adjustments; 64.3% INRs in the therapeutic range; 16.5% INRs < 2.0; 13.2% INRs between 3.1 and 3.9; 4.8% of INRs between 4.0 and 6.0; and 1.2% INRs > 6.0. Twenty-eight warfarin drug interactions were documented in 11 patients (91.7%), including acetaminophen (75.0%) and antibiotics (66.1%). Fifty adverse events in 10 patients was reported, including 49 minor bleeds (e.g., nose bleed, bruise); and 1 major bleed (nose bleed requiring the emergency department and oral vitamin K despite a therapeutic INR). Conclusion LTC octogenarians on warfarin require close monitoring by qualified personnel to maintain therapeutic INRs, manage drug interactions and minimize adverse events. …