Results of two-way sensitivity analysis.

<p><a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0047473#pone-0047473-g003" target="_blank">Figure 3</a> illustrate the different ICERs (cost/QALY) for each combination of values tested for the two parameters (annual rate of intracranial hemorrhage on warfarin and annual rate of stroke on warfarin). Shaded squares represent combinations resulting in positive ICERs and less than $50,000 per QALY gained. ICER  =  incremental cost-effectiveness ratio; QALY  =  quality-adjusted life-years.</p

Results of one-way sensitivity analyses comparing apixaban to adjusted-dose warfarin: parameters for which variations result in positive incremental cost-effectiveness ratios.

<p>ICH  =  intracranial hemorrhage; INR  =  international normalized ratio.</p>*<p>Value of variable at which apixaban was no longer found to be a dominant economic strategy.</p

Base-Case Model Variables and Ranges Used in Sensitivity Analysis.

<p>ECH  =  extracranial hemorrhage; HR  =  hazard ratio; ICH  =  intracranial hemorrhage; INR  =  international normalized ratio; MI  =  myocardial infarction; NA  =  not applicable; NVAF  =  nonvalvular atrial fibrillation; RIND  =  reversible ischemic neurologic event; RR  =  relative risk.</p

Incremental cost-effectiveness plane.

<p>Incremental cost-effectiveness plane showing Monte Carlo estimates of incremental costs and benefits of using apixaban for stroke prevention versus adjusted-dose warfarin. For each one of the 10,000 iterations, values for parameters are randomly selected from their distributions and an ICER is calculated. Points falling above the dotted line have an ICER of >$50,000 per QALY and those falling below the line have an ICER of <$50,000 per QALY. Apixaban was found to be a dominant strategy (less costly, more effective) in 57% of the simulations and cost-effective in 98% of simulations at willingness-to-pay thresholds of $50,000 per QALY. Four thousand of the 10,000 iterations, selected at random, are depicted. ICER  =  incremental cost-effectiveness ratio; QALYs  =  quality-adjusted life-years.</p

One-way sensitivity analysis of baseline rate of ICH on warfarin.

<p>This figure depicts the effect of varying baseline intracranial hemorrhage rates on the ICER. Vertical dotted line demarcates the lower limit of the plausible range (i.e., 0.63% per year).</p

Simple schematic representation of the Markov model.

<p>All patients started at age 65 in the “well” with atrial fibrillation health state and then cycled between health states until death occurred or lifetime follow-up period ended (whichever came first). Only certain transitions were allowed and patients could never transition to a more favorable health state. The length of each cycle was 2 weeks and patients could only experience one event of any kind per cycle. Any health state could lead directly to death (not depicted). A second minor ischemic stroke resulted in a major ischemic stroke and that a second major ischemic stroke resulted in death. Temporary health states (e.g., minor bleed and non-fatal extracranial bleed) are not depicted in the figure. The health states were equivalent for apixaban and warfarin, but the probabilities, costs and utilities (quality-of-life) varied with treatment.</p