Estimating health state utilities associated with a rare disease: familial chylomicronemia syndrome (FCS)

Aims: Familial chylomicronemia syndrome (FCS) is a rare genetic disorder with no currently approved therapies. Treatments are in development, and cost-utility analyses will be needed to examine their value. These models will require health state utilities representing FCS. Therefore, the purpose of this study was to estimate utilities for FCS and an associated episode of acute pancreatitis (AP). Methods: Because it is not feasible to gather a large enough sample of patients with this extremely rare condition to complete standardized preference-based measures, vignette-based methods were used to estimate utilities. In time trade-off interviews, general population participants in the UK and Canada valued health state vignettes drafted based on literature review, clinician input, and interviews with patients. Four health states described variations of FCS. A fifth health state, describing AP, was added to one of the other health states to evaluate its impact on utility. Results: A total of 308 participants provided utility data (208 UK; 100 Canada). Mean utilities for FCS health states ranged from 0.46 to 0.83, with higher triglycerides, more severe symptoms, and a history of AP associated with lower utility values. The disutility (i.e. utility decrease) of AP ranged from –0.17 to –0.25, with variations depending on the health state to which it was added. Utility means were similar in the UK and Canada. Conclusions: The vignette-based approach is useful for estimating utilities of a rare disease. The health state utilities derived in this study would be useful in models examining cost-effectiveness of treatments for FCS.