Inappropriate use of anticoagulant drugs in older adults.

I or inappropriate drug use in older adults is a common and serious problem that can increase mortality and morbidity as a result of deterioration of bodily functions (Fu, Liu, & Christensen, 2004). Inappropriate use of anticoagulant drugs has recently gained interest due to the potential risk of hemorrhage. Warfarin (Coumadin®), which is used for atrial fibrillation, mechanical heart valves, and ischemic attacks, is the most commonly implicated drug of emergency hospitalizations for adverse drug reactions in older adults. Approximately 50% of these hospitalizations involve adults older than 80, with hemorrhage being the primary adverse event (Budnitz, Lovegrove, Shehab, & Richards, 2011). Inappropriate use of warfarin can cause serious hemorrhage in the intracranial area and gastrointestinal system, as well as in the respiratory and genitourinary systems, with risk for fatality. Interestingly, anticoagulant-related major hemorrhage is observed more frequently in older patients (age >75) than in younger patients (Levine, Raskob, Beyth, Kearon, & Schulman, 2004). The mechanism of how aging causes hemorrhage is unknown, but increasing evidence supports that age is an independent factor for major hemorrhage (Levine et al., 2004). Although novel anticoagulant agents (e.g., dabigatran [Pradaxa®], rivaroxaban [Xarelto®], and apixaban [Eliquis®]) have long been anticipated as alternatives to warfarin, the lack of reversal agents, increased risk of gastrointestinal bleeding, and limited evidence in the older adult population are serious concerns (Ogbonna & Clifford, 2013). Inappropriate drug use has also been observed among hospitalized patients and can affect length of stay (Onder et al., 2003). We present one such case from our hospital. An 82-year-old man was hospitalized to undergo total knee arthroplasty. His medical history revealed atrial fibrillation, with irregular use of metoprolol succinate 50 mg and warfarin sodium 5 mg; however, the patient stated he had not used either medication in the previous 5 days. Preoperative tests, including international normalized ratio (INR), were within normal limits. The chosen anesthetic plan was combined spinal/ epidural anesthesia. The operation was completed uneventfully. A continuous epidural infusion of bupivacaine 0.25% was administered for postoperative analgesia. The epidural catheter was scheduled to be removed on the third postoperative day; however, catheter removal was delayed due to an INR of 4.2. The patient was closely monitored for signs of spinal hematoma. Repeated, detailed, and insistent questioning by nurses revealed that he had taken warfarin sodium 5 mg tablets for 3 days during the postoperative period, assuming it to be an analgesic. His cognitive functions were normal, but he was resistant to cooperate. He did not realize the importance of the potential complications due © 20 14 Sh ut te rst oc k.c om /B len d I m ag es Inappropriate Use of Anticoagulant Drugs in Older Adults