Expected Value of Perfect Information (EVPI)

The expected value of perfect information (EVPI) is a metric used in health economics to estimate the maximum amount a healthcare decision-maker would be willing to pay to eliminate all uncertainty in a cost-effectiveness analysis. Essentially, EVPI represents the monetary value of having perfect information regarding all factors that influence the choice between treatment alternatives.

EVPI is calculated by comparing the monetary value of health gains under two scenarios:

1. Current Information: The decision is made based on the current, imperfect information, which includes uncertainty about all relevant factors.

2. Perfect Information: The decision is made with perfect information, eliminating any uncertainty about all factors.

The difference between these two values represents the EVPI, quantifying the benefit of removing all uncertainty from the analysis. By doing so, EVPI provides a measure of the potential value of further research and data collection, guiding decisions on whether the cost of obtaining additional information is justified by the potential health gains and cost savings.

EVPI helps prioritize research investments by highlighting areas where reducing uncertainty would have the greatest impact on decision-making, thereby improving the efficiency and effectiveness of healthcare resource allocation.