Varying Willingness to Pay Based on Severity of Illness: Impact on Health Technology Assessment Outcomes of Inpatient and Outpatient Drug Therapies in The Netherlands

Since 2015, Zorginstituut Nederland (ZIN) has linked disease severity ranges of 0.10 to 0.40, 0.41 to 0.70, and 0.71 to 1.00 with willingness-to-pay (WTP) reference values of €20 000, €50 000, and €80 000 per quality-adjusted life year gained, respectively. We sought to review whether these changes have affected ZIN health technology assessment (HTA) outcomes for specialist and outpatient drugs. ZIN recommendations for specialist and outpatient drugs published between January 1, 2012, and December 31, 2020, that included a pharmacoeconomic report were reviewed. Data were extracted on disease severity, proportional shortfall calculation, reported WTP reference value, outcomes related to the cost-effectiveness of the product, budget impact, and ZIN’s recommendation including rationale for their advice. A total of 51 HTAs were included. Of the 20 HTAs published before June 2015, a total of 9 received positive recommendations, 7 were conditionally reimbursed, and 4 received negative recommendations. None reported WTP reference values. Of the 31 evaluations published after June 2015, a total of 4 products received positive recommendations, 1 was conditionally approved, and 26 received negative recommendations initially. Most products (65%) reported disease severity to be >0.70. Since 2015, most products have fallen within the highest category of disease severity. Although pre-2015 outcomes were varied, post-2015 products overwhelmingly received negative recommendations, and the proportion of products for which price negotiations were recommended has increased. These differences in outcomes may result from the introduction of an explicit WTP reference value, whether or not in combination with the severity-adjusted ranges, but may also reflect other national policy changes in 2015. •Since 2015, The Netherlands has been one of the few countries to introduce explicit willingness-to-pay reference values based on disease severity in health technology assessment (HTA) decision making.•In the same year, a “sluice” was introduced for specialist (hospital) products. Before 2015, specialist products were reimbursed immediately after marketing authorization. Nevertheless, with the introduction of the sluice, the automatic inflow of specialist products with an expected high budget impact is put on hold until assessment by Zorginstituut Nederland and price negotiations are in place. We aimed to describe observed trends in HTA outcomes before and after all (policy) changes in