Development of a Conceptual Model for the Patient Experience of Focal Segmental Glomerulosclerosis (FSGS): A Qualitative Targeted Literature Review

**Background:** Focal segmental glomerulosclerosis (FSGS) is a leading cause of kidney disease that can progress to end stage kidney disease (ESKD). There are no FDA-approved disease-modifying treatments for FSGS, and treatment often involves immunosuppressive therapy with significant side effects. Understanding the patient experience of FSGS is crucial for selecting or developing fit-for-purpose clinical outcome assessments (COAs) for clinical trials. This study aimed to develop a conceptual model (CM) of the adult and pediatric patient experience of FSGS, including disease signs/symptoms, treatment side-effects, and impact on functioning and wellbeing.

**Methods:** This study comprised a systematic review and thematic analysis of qualitative studies with adults and pediatric patients diagnosed with FSGS. Data sources were identified through an electronic database search of journal articles (Medline, Embase, PsycINFO; June 2021) and hand-searching of conference proceedings, patient advocacy group websites, and gray literature. Non-English articles were excluded. Identified data (patient/caregiver quotes, author summaries, and interpretations of patient experiences) were extracted from the articles. Extracted data were qualitatively analyzed aided by ATLAS.ti v7. Codes were applied to data and concepts (symptoms/impacts) were identified, named, and refined. A CM was developed by grouping related concepts into domains.

**Key Results:** In total, 12 sources were identified for analysis: 6 journal articles and 6 series of patient testimonials. Salient sign/symptom/side-effect domains included swelling/puffiness (edema), pain/aches/discomfort, fatigue, weight changes, skin problems, respiratory problems, and sleep problems. Salient impact domains included emotional/psychological wellbeing, physical functioning/activities of daily living, social functioning, and work/school. The most salient symptoms were swelling/puffiness (edema) and fatigue. Other salient symptoms included bloating, weight gain, sleep problems, dry/itchy skin, appetite loss, shortness of breath, and pain. Impacts reported to be of greatest concern included emotional impact of the unknown and unpredictable nature of FSGS, impacts on work/school, and impacts on social wellbeing.

**Clinical Implications:** The conceptual model provides a useful tool to inform the selection and/or development of clinical outcome assessments for use in future FSGS clinical trials. Concept elicitation interviews are recommended to refine the CM, confirm the salient/most bothersome concepts, and confirm the extent of impact on daily life. The refined CM will help ensure that future clinical trials measure outcomes that matter most to patients, including both adult and pediatric populations.