Qualitative Research with Patients and Physicians to Assess Content Validity and Meaningful Change on ESSDAI and ESSPRI in Sjögren's

Introduction: European Alliance of Associations for Rheumatology (EULAR) Sjögren's Syndrome Disease Activity Index (ESSDAI) is a clinician-reported outcome (ClinRO) instrument, assessing Sjögren's disease activity from the physician perspective. EULAR Sjögren's Syndrome Patient Reported Index (ESSPRI) is a patient-reported outcome (PRO) instrument, assessing patient-defined Sjögren's symptom severity. Both instruments are commonly used as clinical trial endpoints and have been psychometrically validated. However, qualitative evidence supporting content validity and what constitutes a meaningful change is limited. Qualitative evidence supporting Physician/Patient Global Assessment of disease activity and symptom severity (PhGA/PaGA) items used within anchor-based analyses for ESSDAI/ESSPRI is also lacking.

Methods: Qualitative, semi-structured, telephone/video interviews were conducted with patients with Sjögren's (n = 12) and physicians who specialise in Sjögren's (n = 10). Interviews explored: appropriateness of ESSDAI domain weights and meaningful improvements on domain/total scores from the physician perspective, appropriateness of ESSPRI's 2-week recall period from the patient/physician perspective, patients' perspectives on meaningful improvements in ESSPRI total scores, and patients'/physicians' interpretation of PhGA/PaGA items.

Results: Most ESSDAI domain weights were considered clinically appropriate. Generally, a one-category improvement in domain-level scores and a 3-point improvement in total ESSDAI scores were considered clinically meaningful. Most patients/physicians considered ESSPRI's 2-week recall period appropriate, and patients considered a 1-to-2-point ESSPRI total score improvement meaningful. PhGA/PaGA items developed for use as ESSDAI/ESSPRI anchors were consistently interpreted.

Conclusions: The findings support use of ESSDAI and ESSPRI as Sjögren's clinical trials endpoints, as well as in clinical practice and other research settings. Qualitative data exploring meaningful change supports existing minimal clinically important improvement (MCII) thresholds.