Presentation (CTI)

OBJECTIVES: Traditional cost-effectiveness analysis does not incorporate the total value of medical intervention since the approach ignores important value elements such as severity, risk preferences, and caregiver burden. The objective of this study was to estimate the total value of disease-and treatment-related attributes associated with X-linked hypophosphatemia (XLH).
METHODS: A web-based survey was performed among a sample of the Swedish, general population (n=1,565) using time-trade off (TTO) and ex ante willingness to pay (WTP) from a parental perspective. Hypothetical descriptions of XLH, varying in symptom severity and type of treatment, were developed in collaboration with medical expertise and presented to respondents. The result of the TTO was translated to number of quality-adjusted life-years (QALYs) lost and the result of the WTP was translated to the value of a statistical case (VSC).
RESULTS: The TTO utility for XLH was 0.46-0.48, corresponding to 41-43 undiscounted QALYs lost for an entire lifetime with XLH. Moving from severe to moderate or mild symptoms in adult age was associated with a significant utility gain of 0.203 (p<0.01) and 0.232 (p<0.01), or 16 to 18 QALYs gained. The WTP to eliminate risk of XLH in a hypothetical unborn child was also significantly higher (indicating more burden) when symptoms were severe compared to when they were moderate (€732 vs. €539, p=0.03) or mild (€732 vs €385, p<0.001), translating to a VSC gain of €3.8 and 6.9 million.
CONCLUSIONS: The results show that XLH is considered to impose a substantial burden on the child and caregiver. Improvements in symptom severity in adult age were associated with a significant WTP value which is 2-4 times higher than the traditional QALY approach when applying a commonly used value of €100,000 per QALY, suggesting a significant underestimation of total value when using conventional approaches.