What’s My Age Again? Exploring the Importance of Patient Age Assumptions in Calculating Severity Modifiers

OBJECTIVES: Severity modifiers were introduced by NICE in 2022 as a method to weight QALYs in technology appraisals (TAs) in which patients are estimated have a high quality-adjusted life expectancy (QALE) shortfall relative to the general population. Assigning modifier thresholds to absolute or relative QALE shortfalls means that baseline age can be a key driver of whether modifier criteria are met, which may not have been an important determinant of eligibility for end-of-life criteria used previously by NICE for QALY weighting. This study examines the sensitivity of modifier decisions to baseline age assumptions, drawing on evidence from NICE technology appraisals published since 2022.

METHODS: General population norms were examined to identify how the maximum comparator QALE levels at which modifiers apply varies by baseline age and gender. A search of NICE TAs published between June 2022 and June 2024 was conducted to identify appraisals in which a severity modifier had been considered, and the data used to determine modifier level (including age and gender, comparator and general population QALE) extracted. Modifier calculations were replicated and a threshold analysis was conducted to identify the approximate baseline age range within which each modifier decision would remain valid.

RESULTS: The analysis of general population QALE demonstrated that in cancers and other disease areas predominantly affecting older populations, absolute shortfall thresholds often cannot be met and relative shortfalls can be highly sensitive to baseline age, meaning that modifiers may be particularly difficult to achieve in certain populations. Results of threshold analyses across NICE TAs indicate the age ranges across which the modifiers applied in final NICE guidance are likely to be valid.

CONCLUSIONS: Results highlight the importance of appropriate baseline age assumptions to severity modifier calculations, as well as identifying age ranges at which absolute or relative shortfalls may be challenging to demonstrate.