Cost-effectiveness of warfarin: trial versus "real-world" stroke prevention in atrial fibrillation.
OBJECTIVE
Previous cost-effectiveness analyses analyzed warfarin for stroke prevention in randomized trial settings. Given the complexities of warfarin treatment, cost-effectiveness should be examined within a real-world setting.


METHODS
Our model followed patients with atrial fibrillation at moderate to high risk of stroke through primary and recurrent ischemic stroke, hemorrhages--intracranial and extracranial, and the resulting disability. Four scenarios were examined: (1) all patients start on warfarin with perfect control, that is, international normalized ratio (INR) values always within range; (2) all patients start on warfarin with trial-like control, where INR can fall outside the recommended range; (3) all patients start on warfarin with real-world INR control; and (4) real-world prescription (and control) of warfarin, aspirin, or neither for warfarin-eligible patients. Reported warfarin discontinuation rates were used. Main outcomes were total number of events, quality adjusted life years, and costs in a US setting.


RESULTS
The total number of primary and recurrent ischemic strokes in a 1,000-patient cohort (age 70 years, lifetime analysis) was 626, 832, 984, and 1,171 in scenarios 1 to 4, respectively. The corresponding mean quality adjusted life years per patient were 7.21, 6.92, 6.75, and 6.67 for scenarios 1 to 4, respectively. Costs per patient were $68,039, $77,764, $84,518, and $87,248 in scenarios 1 to 4, respectively. If "perfect" adherence to warfarin was assumed, except for discontinuations for clinical reasons, strokes would decrease to 503, 737, 909, and 1,120 in scenarios 1 to 4, respectively.


CONCLUSIONS
Clinical and cost outcomes are strongly dependent on the quality of anticoagulation and rates of warfarin discontinuation. Clinicians should work to improve both. Policy makers should use real-world INR control and warfarin discontinuation rates when assessing cost-effectiveness.
Sorensen
Sonja V
SV
United BioSource Corporation, Bethesda, MD, USA. sonja.sorensen@unitedbiosource.com
Dewilde
Sarah
S
Singer
Daniel E
DE
Goldhaber
Samuel Z
SZ
Monz
Brigitta U
BU
Plumb
Jonathan M
JM
D000368:Aged; D000925:Anticoagulants / Q000191:economics* / Q000627:therapeutic use; D001241:Aspirin / Q000627:therapeutic use; D001281:Atrial Fibrillation / Q000150:complications*; D003362:Cost-Benefit Analysis; D006331:Heart Diseases / Q000188:drug therapy* / Q000209:etiology; D006801:Humans; D008955:Models, Cardiovascular; D010975:Platelet Aggregation Inhibitors / Q000627:therapeutic use; D020521:Stroke / Q000209:etiology / Q000517:prevention & control*; D013927:Thrombosis / Q000188:drug therapy* / Q000209:etiology; D014859:Warfarin / Q000191:economics* / Q000627:therapeutic use
D000925:Anticoagulants; D010975:Platelet Aggregation Inhibitors; D014859:Warfarin; D001241:Aspirin