Frailty characterization and patient-reported outcomes in patients with ICI-related inflammatory arthritis and polymyalgia rheumatica

Abstract Objectives Immune checkpoint inhibitors (ICIs) have been associated with immune related adverse events (irAEs), including inflammatory arthritis (IA) and polymyalgia rheumatica (PMR). We aimed to (1) characterize frailty status in patients who develop ICI-IA and ICI-PMR and (2) describe patient-reported outcomes (PROs) across key domains of the disease experience, stratified by frailty status. Methods Consecutive new referrals to our Rheumatology-irAE clinic between April 2024 and April 2025 for evaluation of ICI-IA or ICI-PMR were recruited to this cross-sectional study. Frailty and PROs were measured using validated surveys. PROMIS-29 domain scores were summarized descriptively for patients classified as robust/pre-frail versus frail. Given the small sample size, no inferential statistical testing was performed and no p-values are reported. Results A total of 14 patients (eight males and six females) were included, of whom 10 were characterized as robust or pre-frail and four as frail. The mean ages were similar between those robust/prefrail and frail patients. 2 patients in each group had ICI-PMR. 2 patients in the frail group were diagnosed with ICI-IA, compared to 8 patients in the pre-frail group. Frail patients reported higher median scores in the fatigue and pain interference domains (median T-score fatigue 67.9 [IQR 65.5 to 70.6] versus 53.0 [IQR 48.6 to 57.1]; median T-score pain interference 66.7 [IQR 66.4 to 68.9] versus 58.2 [IQR 57.5 to 62.3]). Median social roles and activities and physical function scores were also lower in the frail group. Conclusion In this small cross-sectional cohort, (1) frailty was present in approximately one-third of patients with ICI-related rheumatic irAEs, and (2) patients classified as frail reported higher fatigue and pain interference scores on PROMIS-29. These observations are descriptive and hypothesis-generating, and are intended to inform the design of larger prospective studies of frailty assessment and geriatric-informed care in this population.