Reasons for Warfarin Discontinuation in ORBIT-AF
Background Warfarin reduces thromboembolic risks in atrial fibrillation (AF), but therapeutic durability remains a concern.
Methods We used clinical data from ORBIT-AF, a nationwide outpatient AF registry conducted at 176 sites with follow-up data at 6 and 12 months, to examine longitudinal patterns of warfarin discontinuation. We estimated associations between patient and provider characteristics and report of any warfarin discontinuation using discrete time proportional odds models.
Results Of 10,132 AF patients enrolled in ORBIT-AF from June 2010 to August 2011, 6,110 (60.3%) were prescribed warfarin, had follow-up data, and were not switched to an alternative oral anticoagulant enrolled from June 2010 to August 2011. Over 1 year, 617 patients (10.1% of baseline warfarin users) discontinued warfarin therapy. Among incident warfarin users (starting therapy within 1 year of baseline survey), warfarin discontinuation rates rose to 17.1%. The most commonly reported reasons for warfarin discontinuation were physician preference (47.7%), patient refusal/preference (21.1%), bleeding event (20.2%), frequent falls/frailty (10.8%), high bleeding risk (9.8%), and patient inability to adhere to/monitor therapy (4.7%). In multivariable analysis, the factors most strongly associated with warfarin discontinuation were bleeding hospitalization during follow-up (odds ratio 10.91, 95% CI 7.91–15.03), prior catheter ablation (1.83, 1.37–2.45), noncardiovascular/nonbleeding hospitalization (1.77, 1.40–2.24), cardiovascular hospitalization (1.64, 1.33–2.03), and permanent AF (0.25, 0.17–0.36).
Conclusions Discontinuation of warfarin is common among patients with AF, particularly among incident users. Warfarin is most commonly discontinued because of physician preference, patient refusal, and bleeding events.
Atrial fibrillation (AF) is the most common cardiac rhythm disorder and an important independent risk factor for stroke. Oral anticoagulation (OAC) with vitamin K antagonists such as warfarin reduces the risk of thromboembolic events associated with AF. However, warfarin management of high-risk AF is inherently challenging because of the need for ongoing international normalized ratio monitoring and dose adjustments. Furthermore, patient and provider concerns about bleeding risk associated with warfarin use may decrease long-term adherence to recommended OAC regimens. As a result, a substantial proportion of AF patients starting anticoagulation will discontinue therapy within 1 year, resulting in increased risk for embolic stroke. Recent studies have suggested that warfarin discontinuation rates in community practice are much higher than those observed in clinical trials.
Unfortunately, many of these data were limited to a single geographic region and did not have information available on specific reasons for discontinuation. Additionally, the major demographic and clinical factors associated with stopping therapy have not been well-defined. Finally, whether discontinuation patterns are similar among prevalent warfarin users compared with newly treated patients has not been fully explored. Therefore, we examined (1) patterns of discontinuation among warfarin-treated patients in an outpatient AF setting, both overall and among those in their first year of therapy; (2) baseline clinical and demographic factors associated with discontinuation; and (3) clinical and demographic factors associated with event-related and patient-related warfarin discontinuation.
Abstract and Introduction
Abstract
Background Warfarin reduces thromboembolic risks in atrial fibrillation (AF), but therapeutic durability remains a concern.
Methods We used clinical data from ORBIT-AF, a nationwide outpatient AF registry conducted at 176 sites with follow-up data at 6 and 12 months, to examine longitudinal patterns of warfarin discontinuation. We estimated associations between patient and provider characteristics and report of any warfarin discontinuation using discrete time proportional odds models.
Results Of 10,132 AF patients enrolled in ORBIT-AF from June 2010 to August 2011, 6,110 (60.3%) were prescribed warfarin, had follow-up data, and were not switched to an alternative oral anticoagulant enrolled from June 2010 to August 2011. Over 1 year, 617 patients (10.1% of baseline warfarin users) discontinued warfarin therapy. Among incident warfarin users (starting therapy within 1 year of baseline survey), warfarin discontinuation rates rose to 17.1%. The most commonly reported reasons for warfarin discontinuation were physician preference (47.7%), patient refusal/preference (21.1%), bleeding event (20.2%), frequent falls/frailty (10.8%), high bleeding risk (9.8%), and patient inability to adhere to/monitor therapy (4.7%). In multivariable analysis, the factors most strongly associated with warfarin discontinuation were bleeding hospitalization during follow-up (odds ratio 10.91, 95% CI 7.91–15.03), prior catheter ablation (1.83, 1.37–2.45), noncardiovascular/nonbleeding hospitalization (1.77, 1.40–2.24), cardiovascular hospitalization (1.64, 1.33–2.03), and permanent AF (0.25, 0.17–0.36).
Conclusions Discontinuation of warfarin is common among patients with AF, particularly among incident users. Warfarin is most commonly discontinued because of physician preference, patient refusal, and bleeding events.
Introduction
Atrial fibrillation (AF) is the most common cardiac rhythm disorder and an important independent risk factor for stroke. Oral anticoagulation (OAC) with vitamin K antagonists such as warfarin reduces the risk of thromboembolic events associated with AF. However, warfarin management of high-risk AF is inherently challenging because of the need for ongoing international normalized ratio monitoring and dose adjustments. Furthermore, patient and provider concerns about bleeding risk associated with warfarin use may decrease long-term adherence to recommended OAC regimens. As a result, a substantial proportion of AF patients starting anticoagulation will discontinue therapy within 1 year, resulting in increased risk for embolic stroke. Recent studies have suggested that warfarin discontinuation rates in community practice are much higher than those observed in clinical trials.
Unfortunately, many of these data were limited to a single geographic region and did not have information available on specific reasons for discontinuation. Additionally, the major demographic and clinical factors associated with stopping therapy have not been well-defined. Finally, whether discontinuation patterns are similar among prevalent warfarin users compared with newly treated patients has not been fully explored. Therefore, we examined (1) patterns of discontinuation among warfarin-treated patients in an outpatient AF setting, both overall and among those in their first year of therapy; (2) baseline clinical and demographic factors associated with discontinuation; and (3) clinical and demographic factors associated with event-related and patient-related warfarin discontinuation.
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