Sanfilippo syndrome (MPS III) is a pediatric-onset, fatal lysosomal storage disorder with no approved therapies. We conducted a mixed method study exploring parent perceptions of MPS III symptoms with greatest impact and meaningful benefits that could be obtained from a noncurative therapy. Using an innovative approach with 25 parents of children with MPS III, we conducted three focus groups comprising two activities: (#1) a moderated exploration of burden and meaningful treatment benefit and (#2) a best–worst scaling (BWS) preference elicitation to quantify the relative importance of benefits that arose during activity #1. BWS Case 1 is an approach to prioritization where respondents choose features that are most and least important to them (in this case, MPS symptoms that parents reported during the focus group) in a series of questions. The balanced, incomplete block design was preset for 12 prioritization sets, each with five features. Investigators entered features in real time and then participants selected the most and least important in each set. Quantitative BWS analysis yielded utility scores from most to least important. Though BWS items varied somewhat across focus groups, the domains and prioritization results were similar. The synergistic combination of moderated discussion and BWS facilitated additional discussion among participants. The BWS results then augmented thematic analysis of qualitative data. A combination of qualitative data and customized BWS conducted in “real time” during focus groups is a novel and effective way to elicit nuanced, actionable data—in this case, about meaningful outcomes in the treatment of rare disease.
