Minimal Important Differences (MID) of the Patient Reported Outcomes Measurement Information System (PROMIS) Computerized Adaptive Test (CAT) Measures in a Single Canadian Lupus Cohort

Objectives The Patient Reported Outcomes Measurement Information System (PROMIS) has been recognized as a potential tool to harmonize research across diseases in the assessment of physical, mental, and social health. Previous studies have demonstrated reliability, validity and responsiveness evidence for PROMIS CAT in systemic lupus erythematosus (SLE).[1] This study extends this evidence by examining minimal important difference (MID) of PROMIS CAT domains. Methods In this longitudinal study, consecutive adult English-speaking SLE patients were invited to participate. Patients completed an assessment using PROMIS CAT’s 13 domains (physical function, mobility, pain behavior, pain interference, ability to participate in social roles, satisfaction with social roles and activities, fatigue, sleep disturbance, sleep-related impairment, applied cognition-abilities, anger, anxiety, and depression) and corresponding legacy instruments at baseline and at 3 and 6 months. The generic anchor question was asked to identify those with symptom severity change. Domain-specific anchor questions were asked at 6 months with responses graded from −7 (greatest worsening) to +7 (greatest improvement), and 0 representing no change. For domain-specific anchors, improvement was defined as >1 and worsening as < −1. Area Under the Curve (AUC) and 95% confidence intervals for each of the 13 domains were calculated and minimal important differences (MID) were derived from the above AUC analysis, also called Anchor-based approach. Results 108 patients (90.7% female) were included. MIDs for PROMIS Physical Function were calculated to be −1.84 in patients that improved and −6.17 in patients who worsened over 6 months (Figure 1). MID for Satisfaction with Social Roles and Activities was −4.40 in patients that improved over 6 months (Figure 1). AUC was considered significant (> 0.7) in PROMIS Physical Function (improved), Satisfaction with Social Roles and Activities (improved), Pain Interference (worsened), fatigue (worsened) and sleep disturbance (worsened). Figure 1: AUC and Anchor-based MID in patients reported worsening and improvement in anchor Q1 (at 6 months) Conclusion In summary, MID for PROMIS CAT in SLE cohort varied significantly among categories. Given patients did not demonstrate very significant change over 6 months as expected in the absence of intervention or change in therapy, MID is to be interpreted cautiously in this setting. Physical function and Satisfaction with Social Roles and Activities were domains in which MID could be derived. References [1.] Moazzami M. Lupus 2021;30:2102-13.