United Kingdom value set for the Functional Assessment of Cancer Therapy Eight Dimension (FACT-8D) preference-based quality of life instrument

Objectives: To develop a value set reflecting the United Kingdom (UK) general population’s preferences for health states described by the Functional Assessment of Cancer Therapy (FACT) eight-Dimension preference-based multi-attribute utility instrument (FACT-8D), derived from the FACT-General (FACT-G) cancer-specific health-related quality-of-life (HRQL) questionnaire.

Methods: A UK online panel was quota-sampled to achieve a general population sample representative by sex and age (18y). A discrete choice experiment (DCE) was used to value health states. The valuation task involved choosing between pairs of health states (choice-sets) described by varying levels of the FACT-8D HRQL dimensions and survival (life-years). The DCE included 800 choice-sets; each respondent was randomly allocated 16 choice-sets. Data were analyzed using conditional logistic regression parameterized to fit the quality-adjusted life-year framework, weighted for sociodemographic variables that were non-representative of the UK general population. Preference weights were calculated as the ratio of HRQL-level coefficients to the survival coefficient.

Results: 2239 panel members opted in, 2125 (95%) completed at least one choice-set, and 2054 (92%) completed 16 choice-sets. Pain and nausea were associated with the largest utility weights, followed by problems with work and sadness. Within dimensions, more severe HRQL levels were generally associated with larger decrements. A preference-weighting algorithm to estimate UK utilities from responses to the FACT-General questionnaire was generated. The worst health state’s value was -0.402, worse than dead.

Conclusions: This value set provides UK population utilities for health states defined by the FACT-8D for use in evaluating oncology treatments.