Methods: We review amendments to NICE’s methods guidelines to show how the recommended discount rates have changed three times since 2004. In particular, we consider the most recent amendment made in April 2013, which states that certain highly effective, non-preventative interventions with health effects lasting more than 30 years can be subject to lower discount rates than others. We discuss how this amendment should be interpreted. We then explore some of the possible consequences of selectively applying lower discounting using examples of cost-effectiveness analyses of alternative interventions.
Results: We show that selectively applying lower discount rates can lead to the health benefits of otherwise similar interventions being valued very differently. This can lead to large differences in cost-effectiveness ratios, which in turn can lead to marked differences in the probability of adoption. We demonstrate the paradoxical result that NICE may prefer to allocate resources to interventions that yield lower health gains than alternative treatments of the same cost. We also show the particular example in which the 30 years criterion means that individuals with shorter remaining life expectancy may not be eligible for treatment, whereas younger individuals with longer remaining life expectancy are.
Conclusions: There seems to be no valid reason to apply favourable discount rates selectively. Consequently, the differences in the valuation of health effects, cost-effectiveness ratios and the probability of adoption all appear to be unjustifiable inconsistencies. Not only is the selective application of favourable discount rates not justified on theoretical grounds, but it leads to real concerns regarding equitable resource allocation between patients, especially regarding the eligibility of older people. While there are good arguments for NICE to reduce their reference case discount rate from the current 3.5%, any reduction should be applied to all interventions and be accompanied by a review of the cost-effectiveness threshold. NICE should take to care to uphold high standards in its methods guidance when revising its discounting recommendations.