OBJECTIVES:

Rare diseases can have a considerable impact on patients’ health-related quality of life (HRQoL). The National Institute for Health and Care Excellence’s (NICE) Highly Specialised Technologies (HST) process evaluates treatments indicated for very rare diseases. For interventions that have the potential to restore normal physiology in rare disease sufferers, capturing long-term impact on HRQoL in economic evaluations may be particularly challenging, due to sparsity of data. The aim of this study is to explore how long-term HRQoL benefit was modelled in NICE HSTs of treatments that could restore patient health to near that of the general population.

METHODS:

A targeted literature review was conducted of NICE HSTs evaluating gene therapies, enzyme replacement therapies (ERTs) and alternatives to ERTs for very rare diseases. These therapies were selected as they have the potential to restore or maintain normal physiology in treated patients. Information extracted included modelling approach, modelled outcomes, health states used, and derivation of utilities.

RESULTS:

Nine NICE HSTs were identified for data extraction and critical analysis, four assessing gene therapies, and five assessing ERTs or alternatives to ERTs. Four evaluations included a health state equivalent to general population health, in which general population utility values were used. This approach to modelling utilities was accepted by NICE in two submissions where the treatment was generally accepted to restore normal physiology, criticised but not modified in one submission, and altered by the NICE Evidence Review Group in one case where the disease was judged to have an impact on HRQoL despite treatment.

CONCLUSIONS:

In NICE HST appraisals of treatments which have the potential to restore normal physiology, there is a precedent for use of utilities equivalent to the general population. The acceptance of this assumption by NICE in more than one case demonstrates that this approach can be acceptable to healthcare payers under appropriate circumstances.