Background/Purpose: Lupus nephritis (LN) is an autoimmune disease characterized by inflammation of the kidneys, a severe manifestation of systemic lupus erythematosus (SLE) that occurs in approximately 50% of SLE patients. To evaluate treatment benefit effectively, it is critical that patient-reported outcome (PRO) measures are fit-for-purpose and have strong evidence of content validity in the specific context of use, to serve as trial endpoints and support product label claims. SF-36, Lupus-QoL, and FACIT-Fatigue are commonly used clinical trial endpoints in SLE populations, with demonstrated evidence of content validity in this population. Similar evidence of their content validity in an LN population is lacking. A prior qualitative literature and online blog review and concept elicitation interviews with LN patients identified key symptoms (i.e., skin rash, joint pain, joint stiffness, and swelling of the legs/feet) and symptom properties (i.e., severity) not adequately assessed by these three PRO measures. Novel PRO symptom severity items were developed to address conceptual gaps. This study aimed to evaluate the content validity of SF-36, Lupus-QoL, FACIT-Fatigue, and novel PRO items in a sample of LN patients.

Methods: Qualitative, semi-structured, telephone cognitive interviews were conducted with 20 US adult patients with a diagnosis of LN. To evaluate the content validity of the existing PRO measures, participants’ understanding and relevance of the concepts to their experience of LN was assessed. Participants completed the novel PRO items using a ‘think aloud’ process. Questioning explored understanding and relevance of item wording, instructions, different recall periods (24-hour vs 7-day), and response scales (numeric rating scale (NRS) vs verbal response scale). Interviews were conducted in two rounds to allow for modifications to novel PRO items and subsequent re-testing. Qualitative analysis of verbatim interview transcripts was performed.

Results: Symptom and impact concepts assessed by SF-36, Lupus-QoL, and FACIT-Fatigue were well understood, with most considered relevant by the majority of participants asked. Symptoms assessed by the novel PRO items were considered relevant to most participants. Participant feedback informed modifications to the novel PRO items and instructions to improve clarity and understanding between rounds. Each iteration of the item wording and instructions were understood and interpreted consistently by all participants asked. The selected 7-day recall period and NRS in the final iteration of the PRO items were understood, relevant, and appropriately endorsed.

Conclusion: Findings support the content validity of the symptom and impact concepts assessed by SF-36, Lupus-QoL, FACIT-Fatigue in LN patients, providing evidence of their suitability as supportive efficacy endpoints in LN randomized controlled trials. Content validity evidence was also generated for the novel PRO items in LN patients, supporting their suitability to address conceptual gaps in existing PRO measures. Further research is required to establish the psychometric validity of the novel PRO items in a LN population.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/generation-of-evidence-supporting-the-content-validity-of-sf-36-lupus-qol-and-facit-fatigue-and-newly-developed-patient-reported-outcome-pro-symptom-items-to-address-conceptual-gaps-for-use-in-pa/