Table 1.
Sample Calculation of Expected Value of Perfect Information Using a Simulated Output of Costs, Effectiveness, and Net‐Monetary Benefit for 10 Iterations
| Treatment Strategy | Optimal Choice | Maximum Net Benefit ($) | Opportunity Loss (EVPI) | ||||||
|---|---|---|---|---|---|---|---|---|---|
| Warfarin | LAA Occlusion Device | ||||||||
| Cost ($) | Effectiveness (QALY) | NMB (WTP=$100 000) | Cost ($) | Effectiveness (QALY) | NMB (WTP=$100 000) | ||||
| Iteration 1 | 19 688.00 | 4.58 | 438 601.60 | 32 138.60 | 4.52 | 419 543.20 | Warfarin | 438 601.60 | 19 058.40 |
| Iteration 2 | 19 881.70 | 4.58 | 437 745.50 | 20 514.90 | 4.84 | 463 363.40 | LAA occlusion | 463 363.40 | 0 |
| Iteration 3 | 20 766.80 | 4.54 | 433 453.80 | 19 104.70 | 4.86 | 467 280.00 | LAA occlusion | 467 280.00 | 0 |
| Iteration 4 | 20 168.70 | 4.55 | 435 035.00 | 26 638.20 | 4.67 | 440 207.70 | LAA occlusion | 440 207.70 | 0 |
| Iteration 5 | 20 220.20 | 4.58 | 437 617.40 | 24 538.20 | 4.75 | 449 992.30 | LAA occlusion | 449 992.30 | 0 |
| Iteration 6 | 20 343.20 | 4.56 | 435 430.20 | 25 111.00 | 4.71 | 445 595.70 | LAA occlusion | 445 595.70 | 0 |
| Iteration 7 | 20 780.00 | 4.55 | 434 030.50 | 31 271.00 | 4.55 | 424 200.50 | Warfarin | 434 030.50 | 9830.0 |
| Iteration 8 | 20 961.10 | 4.55 | 433 893.70 | 28 563.70 | 4.64 | 435 406.70 | LAA occlusion | 435 406.70 | 0 |
| Iteration 9 | 20 019.80 | 4.55 | 435 033.60 | 27 927.60 | 4.62 | 434 547.60 | Warfarin | 435 033.60 | 486.0 |
| Iteration 10 | 19 700.80 | 4.57 | 437 555.70 | 21 898.90 | 4.79 | 457 368.10 | LAA occlusion | 457 368.10 | 0 |
| Overall expectation | 20 253.00 | 4.56 | 435 839.70 | 25 770.70 | 4.70 | 443 750.50 | LAA occlusion** | 446 688.00 | 2937.40 |
Example of EVPI calculation: Each row of Table 1 represents the costs, effectiveness, and NMB for each treatment strategy for 10 sample outer‐loop iterations. With current information, we would choose the treatment strategy with the highest overall expected net benefit, which in this case is LAA occlusion with an expected net benefit of $443 750.50 (shown with **). With perfect information, we would choose the treatment strategy with the greatest net benefit for each iteration, that is, we would choose warfarin for iteration 1, an LAA occlusion device for iteration 2 to 6, warfarin for iteration 7, and so forth. If the preferred strategy for the iteration is different from the overall optimal strategy (ie, LAA occlusion device), then an opportunity cost is associated with that iteration. The opportunity cost for the iteration is the difference in NMB for the treatment strategies. In iteration 1, for example, warfarin is the preferred option; therefore, an opportunity cost exists for this iteration and is equal to the NMB of warfarin ($438 601.60)—NMB of LAA occlusion ($419 543.20). The average opportunity cost across all of the outer‐loop iterations represents the EVPI, which, in this example of 10 iterations, is $2937.40. The higher the EVPI, the larger the opportunity cost of an incorrect decision. EVPI indicates expected value of perfect information; LAA, left atrial appendage; NMB, net monetary benefit; QALY, quality‐adjusted life year; WTP, willingness to pay.