Severity Weights in NICE Technology Appraisals

NICE replaced the modifier for “End of Life” with “severity” in the latest version of its methods guidance in January 2022.

Committees are now instructed to consider the severity of a condition, defined as the future health lost by people living with the condition with standard care in the NHS. It is measured in terms of Absolute and Proportional Shortfall (AS and PS). Both measure the difference between the number of discounted Quality Adjusted Life Years (QALYs) patients would be expected to experience over the remainder of their lives under current care compared to the general population of the same age and sex.

Data from the first year of implementation of the 2022 methods manual (57 topics with at least 1 committee meeting) shows that fewer topics met the 1.2 and 1.7 severity modifier than had been anticipated during the methods manual consultation. This is an unexpected finding and therefore, work is required to explore what explains the difference between what NICE anticipated the use of 1.2 and 1.7 severity modifiers would be in technology appraisals, and what has been observed so far.

The outcomes of this work will inform what next steps NICE might take to address this issue.

The DSU report:

Examines differences between severity weights in the set of appraisals used to determine how severity would be defined and weighted (pre 2022 appraisals) and those appraisals where these were implemented (post 2022).

Demonstrates how severity and its constituent components (AS and PS) are related to age and end of life.

Provides empirical evidence and interpretation to assist NICE in determining future development of severity weights.   

DSU Report

Wailoo, A. Severity Weights in NICE Technology Appraisals. 2024