Patient-Reported Outcomes Measurement Information System (PROMIS) measures are used increasingly in clinical care. However, for juvenile idiopathic arthritis (JIA), scores lack a framework for interpretation of clinical severity, and minimally important differences (MID) have not been established, which are necessary to evaluate the importance of change.
We identified clinical severity thresholds for pediatric PROMIS measures of mobility, upper extremity function (UE), fatigue, and pain interference working with adolescents with JIA, parents of JIA patients, and clinicians, using a standard setting methodology modified from educational testing. Item parameters were used to develop clinical vignettes across a range of symptom severity. Vignettes were ordered by severity, and panelists identified adjacent vignettes considered to represent upper and lower boundaries separating category cut-points (i.e., from none/mild problems to moderate/severe). To define MIDs, panelists reviewed a full score report for the vignettes and indicated which items would need to change and by how much to represent "just enough improvement to make a difference."
For fatigue and UE, cut-points among panels were within 0.5 SD of each other. For mobility and pain interference, cut-scores among panels were more divergent, with parents setting the lowest cut-scores for increasing severity. The size of MIDs varied by stakeholders (parents estimated largest, followed by patients, then clinicians). MIDs also varied by severity classification of the symptom.
We estimated clinically relevant severity cut-points and MIDs for PROMIS measures for JIA from the perspectives of multiple stakeholders and found notable differences in perspectives.