Burden of illness among subgroups of patients with primary Sjögren's syndrome and systemic involvement.

OBJECTIVES: To describe how patients with primary SS (pSS) and systemic organ involvement are classified and clustered in routine practice. METHODS: This multinational, cross-sectional survey of real-world quantitative data was conducted across Europe and the US. Rheumatologists who treated seven or more adult patients per month with pSS and current/past systemic manifestations undertook a survey before completing a patient record form capturing demographic, clinical and treatment information for their next six eligible patients. Patients with a completed patient record form were invited to complete a patient self-completion questionnaire capturing insights into their disease and treatment. Subgroups were defined by physicians' assessment of disease severity; clusters were derived based on key clinical characteristics using latent class analysis. RESULTS: Rheumatologists completed 316 physician surveys and 1879 patient record forms; 888 patients completed the patient self-completion questionnaire. pSS severity reflected organ involvement and symptomatology. Latent class analysis produced five clusters distinguished by the organ systems involved and the presence of pain and fatigue symptoms at the time of the survey. A minority of patients [n = 67 (4%)] were categorized with multiple organ involvement and the highest frequency of pain and fatigue. A total of 324 patients (17%) were categorized as 'low burden'. The remaining three clusters exhibited high frequencies of articular involvement but were distinguished by the extent of other organ system involvement. CONCLUSION: Cluster analysis using a real-world cohort of patients with pSS and systemic organ involvement highlights the heterogeneous presentation of patients with pSS and confirms the importance of pain and fatigue as well as organ involvement when determining disease burden.