Background: In 2017, The Canadian Agency for Drugs and Technologies in Health (CADTH) made a large change in their Guidelines for the Economic Evaluation of Health Technologies, by decreasing the reference case discount rate from 5% to 1.5%. This change may substantially impact the incremental cost-effectiveness ratios (ICERs) submitted to Canadian funding authorities. Since it is not required to include the 5% discount rate in sensitivity analysis, decision makers may find comparing ICERS calculated at different time-points challenging.
Methods: This paper constructs look-up tables for making such comparisons under three scenarios that involve either constant costs and benefits and linear changes in costs and/or benefits over time.
Results: Cost-benefit projections that most closely emulate patterns observed with surgical interventions often combined with short-term prescription drug therapies can produce ICERs that are over 30% higher when a 5.0% discount rate is applied in comparison to one at 1.5%.
Conclusions: There are occasions when original data and methodologies are unavailable that can be leveraged for reanalysis when discount rates change. In the instance of the Canadian context, the recommended change in reference discount rate as of 2017 was substantial requiring methods for comparing cost-effectiveness analyses conducted both before and after the change in discount rate. This paper offers a method for making such comparisons.