Introduction: The Profile of Fatigue and Discomfort-Sicca Symptoms Inventory-Short Form (PROFAD-SSI-SF) is a 19-item patient-reported outcome (PRO) measure to assess pain, fatigue, and dryness in patients with primary Sjögren's syndrome (pSS). This analysis identified concepts important to measure, and evaluated the content validity and measurement properties of the PROFAD-SSI-SF, in patients with pSS.
Methods: Qualitative analyses (GSK Study 208396) used transcripts from an online concept elicitation (CE) discussion forum with patients with pSS and interviews with key opinion leaders (KOLs) to finalize a disease model depicting important concepts for patients with pSS. Cognitive debriefing (CD) interviews with patients with pSS were conducted to further evaluate the content validity of the PROFAD-SSI-SF. Quantitative analyses (GSK Study 213253) used post hoc analyses of blinded data from a phase 2 trial to assess PROFAD-SSI-SF measurement properties.
Results: The CE discussion forum (N = 46) revealed dryness (oral 87.0%, ocular 73.9%, cutaneous 37.0%, vaginal 23.9%, nasal 15.2%, otic 6.5%), pain (89.1%), and fatigue (87.0%) as the most reported symptoms. KOLs (N = 5) found the concepts identified in the disease model accurate and understandable, and confirmed that PROs used in pSS studies should focus on dryness, joint pain, and fatigue. In the CD interviews (N = 20), of the 19 participants asked, all found the PROFAD-SSI-SF easy to understand, and 14/19 items were considered relevant by ≥ 18/20 participants. The quantitative analyses found an acceptable fit of the PROFAD-SSI-SF factor structure, with adequate internal consistency, test-retest reliability, convergent validity with other PRO measures, known-groups validity with Patient Global Assessment, and ability to detect change in patients with pSS.
Conclusion: The final disease model confirmed that the PROFAD-SSI-SF assesses concepts that are relevant and important to patients with pSS. Our findings support the content validity and measurement properties of the PROFAD-SSI-SF as a fit-for-purpose PRO measure appropriate for use in clinical trials in patients with pSS. CLINICAL TRIAL REGISTRATION NUMBER FOR THE PHASE 2 TRIAL: Clinicaltrials.gov NCT02631538.
Keywords: Autoimmune disease; Content validity; Instrument validation; PROFAD-SSI-SF; Patient-reported outcomes; Primary Sjogren’s syndrome; Psychometric properties; Qualitative research.
Primary Sjögren’s syndrome (pSS) is a disease where the immune system attacks the body, causing a number of symptoms, most notably dryness (sicca) of the eyes and mouth. The Profile of Fatigue and Discomfort–Sicca Symptoms Inventory–Short Form (PROFAD-SSI-SF) is a questionnaire for patients with pSS that asks about their symptoms. This paper evaluates how relevant the PROFAD-SSI-SF questions are to patients with pSS, and how consistently and accurately the questionnaire can measure changes in their symptoms. We reviewed information about the symptoms and impacts of pSS from an online discussion forum for patients with pSS. Patients said that dryness, fatigue, and pain were the symptoms that most affected their day-to-day lives and well-being. We combined this information with previous research on pSS to design a diagram explaining the key symptoms and day-to-day impacts of pSS, which was reviewed by five experts in pSS. In doing so, we aimed to confirm whether the most important things to patients about living with pSS are asked in the PROFAD-SSI-SF questionnaire. Next, we asked 20 patients with pSS how easy they found the PROFAD-SSI-SF to complete and if any important concepts were missing; they reported that the PROFAD-SSI-SF was easy to fill in and that the important questions were included. Finally, we looked at data from a clinical trial that used the PROFAD-SSI-SF and found it accurately measures changes in symptoms of patients with pSS. This means that the PROFAD-SSI-SF could be used in clinical trials to help assess new medicines for pSS.
© 2022. The Author(s).