Do patient preferences for core outcome domains for chronic gout studies support the validity of composite response criteria?

Abstract

To determine patient-derived weights or prioritization for core outcome domains in chronic gout clinical studies. Three patient groups participated in a conjoint decision-making exercise using 1000Minds software, which asked participants to make repeated judgments regarding which of 2 hypothetical patients with gout represented the best response to treatment. Each scenario compared 2 patients on the basis of change in 2 of 5 core outcome domains at a time. Agreement of 80% of the group was required to answer each scenario. Re-voting was performed once after discussion in instances of disagreement. The relative importance accorded to each outcome domain was different across the 3 groups of patients. There was some consistency that tophi was the least or second to least important outcome domain for every group and pain between attacks was ranked in the bottom third of priority for all groups. Gout attacks were ranked as the second or third most important domain in each group. However, the relative importance of serum urate (SUA) and activity limitations was quite different among the 3 groups, with 1 group ranking SUA as the most important outcome and 1 group ranking it as the second to least important outcome. Despite some consistency in the relative value of some outcome domains for chronic gout studies, there is sufficient disagreement in the relative importance of other domains of outcome to challenge the validity of constructing a composite index of response that would be applicable to most gout patients.