It is established that the current cost effectiveness health technology assessment (HTA) paradigm does not appropriately value rare disease technologies. Social willingness-to-pay (SWTP) has been suggested to be higher for rare disease technologies, it's inclusion into existing HTA framework could better reflect social preferences (SP) and enable a more equitable evaluation of rare disease technologies. Our study aims to estimate SP and SWTP for a rare disorder, CLN2 disease.

Relevant attributes for CLN2 disease were developed and validated by literature review and focus groups with patient's primary caregivers. An elicitation survey (discrete choice experiment (DCE) WTP and relative social willingness to pay (RS-WTP)) was developed using the selected attributes and levels of each attribute. The survey instruments and attributes/levels were tested and validated in a pre-pilot survey (n = 103) and a subsequent pilot survey (n = 286) of the United Kingdom (UK) general population. Information about CLN2 disease was provided to respondents and their understanding of the disease was tested including assessment of framing effects. The main survey with the general UK population (n = 4,009) is now complete.

Eight hundred and twenty-six people were contacted, of which 286 completed the DCE, 113 abandoned the survey before the DCE and 92 abandoned after the DCE. There were no significant differences in characteristics of respondents completing the DCE and those starting but not completing the DCE. Median survey completion time was 20 minutes with 90 percent of participants completing in a single sitting. Median score for the understanding test was 3 (Min = 0 and Max = 4). Incoherencies in WTP estimates were analyzed enabling us introduce relevant modifications and select the most appropriate attribute levels.

DCE and RS-WTP potentially are appropriate methods for assessment of social preferences. The selected attributes/levels for the experiment in CLN2 disease have been validated in this pilot.