The influence of mental illness on adherence among patients who should be taking warfarin is not well understood.
Nearly one-third of Americans have been diagnosed with a mental health condition (MHC).1 Research suggests these patients may be receiving suboptimal care for a range of conditions.2-4 The influence of mental illness on patients who should be taking warfarin is not well understood.
Warfarin is an oral anticoagulant with a very narrow therapeutic index. Warfarin carries the burden of increasing patients’ risk of hemorrhage, often involves a complex dosing schedule, and requires frequent monitoring of the international normalized ratio (INR). When patients with MHCs are placed on this therapy, clinicians may be concerned about whether patients can safely take the medication as prescribed and adhere to the necessary monitoring.
Current practice guidelines don’t address whether mental illness should be considered when deciding on appropriate anticoagulant therapy. This is alarming, as potential adverse events for a patient who cannot safely take warfarin include major bleeding and thromboembolic events.
A 2003 chart review looked at patients with atrial fibrillation (AF) at a Veterans Health Administration (VHA) facility. Patients with a diagnosis of substance use disorder, depressive disorder, anxiety disorder, psychotic disorder, dysfunctional personality disorder, and bipolar disorder were included in the group of patients with MHCs. Patients with MHCs were less likely to be prescribed warfarin compared with patients without MHCs (48.5% vs 28.9%, respectively; P = .004).5
Among patients placed on warfarin and monitored by the VHA anticoagulation clinic, patients with MHCs were more likely to have high INR values. There was also a trend toward higher rates of subtherapeutic INRs. Patients with MHCs spent less time in the therapeutic INR range of 2.0 to 3.0 (56.8% [standard deviation (SD): ± 16.9] vs 65.9% [SD: ± 18.2] of days spent in the therapeutic INR range; P = .04) and more time at supratherapeutic levels greater than 5.0 than patients without MHCs (9.0% [SD: ± 9.8] vs 3.4% [SD: ± 7.1] of days spent outside the therapeutic INR range; P = .01).5
Warfarin therapy in patients with MHCs has proved to be a concern. Although patients with MHCs often have greater comorbidity, including stroke risk factors, the percentage of warfarin-eligible patients who receive treatment remains low. For patients placed on warfarin therapy, having higher INR values may increase the risk of hemorrhage. Pharmacists addressing warfarin nonadherence in patients with MHCs will help keep patients within therapeutic INR ranges and improve outcomes.
In a separate review of patients with AF and heart failure, the need for patient-centered approaches to address adherence issues with thromboprophylaxis was examined. The presence of an MHC was identified as a condition-related factor impacting adherence. Cognitive and functional impairment, stress, and depression may all lead to failure to comply with appropriate INR monitoring or to reduced adherence due to cognitive or physical inability to self-administer medications. Therefore, including a mental health clinician in the multidisciplinary team may be beneficial.6
When patients with MHCs are placed on warfarin therapy, it is important that they receive education and understand not only why they are taking the medication but also the implications of nonadherence. If a patient is not directly involved with this process, it is important for the patient’s caregiver to receive this information. A patient-centered care plan should also consider where and when patients will have INR testing; what medication, lifestyle, and dietary changes can influence INR; who to contact for a refill; what adverse events to expect; and what to do in case of an emergency. Also, depending on the MHC, particular patients may benefit from novel anticoagulants. Pharmacists may be able to intervene to help promote these options to prescribers.
Nonadherence to warfarin is a major problem in patients with MHCs and can have severe consequences. Patient-centered treatment and care should focus around patients’ individual needs and preferences. Most importantly for patients with MHCs, consideration for treatment with warfarin should be based on individual stroke risk, ability to tolerate anticoagulation without bleeding, and access to adequate anticoagulation monitoring.6
Dr. Resseguie is an advanced practice anticoagulation pharmacist for the Brigham & Women’s Hospital Anticoagulation Management Service in Boston, Massachusetts.Steven Lacey is a PharmD Candidate at Massachusetts College of Pharmacy and Health Sciences.