Are Discount Rates Too High? Population Health and Intergenerational Equity

Empirical Development of a Behavioral Intervention for African American/Black and Latino Persons with Unsuppressed HIV Viral Load Levels: An Application of the Multiphase Optimization Strategy (MOST) Using Cost-Effectiveness as an Optimization Objective

We used results from an optimization randomized controlled trial which tested five behavioral intervention components to support HIV antiretroviral adherence/HIV viral suppression, grounded in the multiphase optimization strategy and using a fractional factorial design to identify intervention components with cost-effectiveness sufficiently favorable for scalability. Results were incorporated into a validated HIV computer simulation to simulate longer-term effects of combinations of components on health and costs. We simulated the 32 corresponding long-term trajectories for viral load suppression, health related quality of life (HRQoL), and costs. The components were designed to be culturally and structurally salient. They were: motivational interviewing counseling sessions (MI), pre-adherence skill building (SB), peer mentorship (PM), focused support groups (SG), and patient navigation (short version [NS], long version [NL]. All participants also received health education on HIV treatment. We examined four scenarios: one-time intervention with and without discounting and continuous interventions with and without discounting. In all four scenarios, interventions that comprise or include SB and NL (and including health education) were cost effective (< $100,000/quality-adjusted life year). Further, with consideration of HRQoL impact, maximal intervention became cost-effective enough to be scalable. Thus, a fractional factorial experiment coupled with cost-effectiveness analysis is a promising approach to optimize multi-component interventions for scalability. The present study can guide service planning efforts for HIV care settings and health departments.

Trends in Author-Reported Cost-Effectiveness Thresholds in the United States from 1995 to 2018: Implications for Discount Rates

Background

Decisions based on cost-effectiveness analyses (CEAs) using equal discount rates for health and cost outcomes are consistent with using a constant cost-effectiveness threshold over time. We sought to analyze trends in author-reported cost per quality-adjusted life-year (QALY) thresholds from CEAs published for the US setting over 24 y to retrospectively assess whether the recommended equal discount rates for costs and health were consistent with trends in the CEA literature.

Methods

We used the Tufts CEA Registry to assess whether author-reported cost-effectiveness thresholds changed in CEAs published for the US setting between 1995 and 2018 and back-calculated the implied discount rate for health based on these trends for inflation-adjusted cost-effectiveness thresholds and an annual discount rate for costs of 3%.

Results

We found 1995 CEAs published for the US setting and found that average nominal and inflation-adjusted cost-effectiveness thresholds increased over that time period. The discount rate for health would need to equal 2.43% to 2.48% (depending on the subset of CEAs analyzed) to be consistent with the observed trends in inflation-adjusted author-reported cost-effectiveness thresholds. We also found that restricting our analysis to currency years between 1995 and 2014 would result in a back-calculated discount rate for health of 2.99% to 3.28%.

Conclusions

We found that CEA researchers have implicitly assumed that inflation-adjusted cost-effectiveness thresholds in the United States have been increasing over time (1995–2018), which is inconsistent with the recommended and prevailing choice of equal discount rates for health and cost outcomes. Our results are sensitive to the cutoff year used in the analysis.

Highlights

We show visually and through equations that the recommended and prevailing practice of using equal discount rates for cost and health outcomes in cost-effectiveness analyses (CEAs) logically implies a constant inflation-adjusted cost-effectiveness threshold over time. Using data from the Tufts CEA Registry, we found that author-reported cost-effectiveness thresholds used in CEAs published for the US setting with currency years between 1995 and 2018 increased over time (both with and without adjustment for inflation). Assuming an annual discount rate for costs equal to 3%, the discount rate for health would need to equal approximately 2.5% to preserve consistency across decisions taken at different dates given the observed trends in inflation-adjusted author-reported cost-effectiveness thresholds. This finding depends on the cutoff year used in the analysis (data from currency years 1995–2014 would support use of equal discount rates, whereas data after 2014 would suggest a sharper trend toward increasing cost-effectiveness thresholds).