Why are longer time horizons important in economic evaluations?

• A. They reduce the overall cost by limiting follow-up.
• B. They capture downstream costs and long-term effects.
• C. They focus only on immediate outcomes.
• D. They standardize the measurement period across interventions.

Answer: (B)

Longer time horizons matter because they let the analysis include all costs and health outcomes that can occur over the full course of a condition or treatment. Some benefits, harms, and costs don’t appear right away but emerge years later—long-term survival gains, chronic side effects, ongoing care needs, maintenance treatments, and broader economic impacts like lost productivity or caregiver time. If you use too short a horizon, you miss these downstream effects and the estimated cost-effectiveness can be biased, typically underestimating benefits or costs. Extending the horizon (with appropriate discounting) provides a more complete view of value and supports decisions that reflect real-world outcomes over time. The remaining options don’t capture this idea: limiting follow-up reduces information about long-term outcomes; focusing only on immediate outcomes ignores later effects; standardizing the measurement period is about comparability, not about ensuring you capture long-term consequences.