BACKGROUND: Budget impact models (BIMs) can be highly sensitive to their assumptions, particularly market share uptake of the new product. Therefore, it is important to select the appropriate method for estimating changes in market share, given that future values can be difficult to predict. In addition, a BIM with several comparators and a multiple-year time horizon may require a large market share table with many inputs, which can be cumbersome for users to modify if the table is not at least partially automated. We compare multiple methods for forecasting market share uptake for use in BIMs, and present an approach to automating market share table adjustments to simplify and improve the user experience.

CONCEPT: Various distribution methods for estimating market share uptake can be applied, including linear, exponential, logarithmic, and sigmoidal growth curves. For example, logarithmic distribution represents rapid initial uptake before tapering off. In contrast, sigmoidal growth correlates to slow initial uptake, followed by accelerated uptake and ending with a plateau, resembling an S-curve on a graph. When considering how the market share values for other comparator products are adjusted in the model, an automated approach can be developed in Microsoft Excel using calculations instead of direct input cells. The approach assumes future market share for comparators are reduced in proportion to their current market share values.

CONCLUSIONS: Selecting the most appropriate distribution method for market share uptake depends on the assumptions for how the new product would be adopted in the market. For BIMs, we recommend including multiple options to accommodate for different uptake scenarios. It is also important to balance the user’s ability to customize the model and ease of use when considering either a manual input or automated approach for modeling BIM market share scenarios.