This document discusses how epidemiology and forecasting in the pharmaceutical industry are changing. Traditionally, forecasts were based on prevalence data and static patient models. However, the industry is shifting towards prevention and earlier treatment, requiring forecasts based on incidence and dynamic patient models that account for factors like disease progression, treatment switching, and market uptake rates. Dynamic models provide more accurate forecasts by considering how patient populations and treatment paradigms evolve over time. They also help demonstrate cost-benefits to regulators and payers, as the industry faces increasing pressure for cost containment. Going forward, epidemiology and forecasting will need to move from static to dynamic approaches to keep up with these changes.