NEW evidence suggests that pre-existing hip osteoarthritis does not increase the risk of developing immune checkpoint inhibitor–induced inflammatory arthritis (ICI-IA), offering reassurance for clinicians managing patients with cancer and coexisting degenerative joint disease.
Immune checkpoint inhibitors (ICIs) have transformed outcomes in many cancers but are frequently associated with immune-related adverse events, including inflammatory arthritis. Whether underlying joint disease predisposes patients to ICI-IA has remained unclear. To address this question, researchers evaluated the role of hip osteoarthritis as a potential risk factor in patients receiving ICI therapy.
Assessing Hip OA Before ICI Treatment
The study included 309 patients treated with ICIs for thoracic cancers who had undergone CT imaging of the abdomen and pelvis within one month of starting immunotherapy. Hip osteoarthritis was assessed directly from CT scans by a radiologist and defined as a Kellgren–Lawrence grade of 2 or higher in either hip. Clinical records were reviewed to identify cases of ICI-IA and other immune-related adverse events.
Of the cohort, 103 patients had radiographic evidence of hip osteoarthritis at baseline. The overall cumulative incidence of ICI-IA was 54.8 cases per 1,000 person-years.
No Increased Risk Linked to Hip Osteoarthritis
Rates of ICI-IA did not differ significantly between patients with and without hip osteoarthritis. In time-to-event analyses, hip OA was not associated with the development of ICI-IA, and this finding remained consistent after adjustment in Cox proportional hazards models.
Interestingly, higher body mass index was associated with a modest but statistically significant reduction in the risk of developing ICI-IA. These findings suggest that degenerative joint changes seen on imaging do not predispose patients to immune-mediated inflammatory arthritis once ICI therapy is initiated.
Survival Signals in ICI-Associated Arthritis
Survival analyses revealed additional clinically relevant insights. Overall survival did not differ by hip osteoarthritis status. However, patients who developed ICI-IA had significantly improved survival compared with those who did not. Higher BMI was also associated with improved survival, while more advanced cancer stage predicted worse outcomes.
The association between ICI-IA and reduced mortality aligns with prior observations linking immune-related adverse events to enhanced antitumour immune activity.
Clinical Implications
The authors conclude that CT-derived hip osteoarthritis should not be considered a risk factor for ICI-IA in patients with thoracic malignancies. These findings may help clinicians counsel patients with pre-existing osteoarthritis who are starting immunotherapy and avoid unnecessary concern about arthritis risk.
Importantly, the observed survival benefit among patients who develop ICI-IA adds to growing evidence that immune-mediated toxicity may be a marker of favourable treatment response. Further studies are needed to clarify the mechanisms underlying these associations and to refine risk stratification for immune-related adverse events in cancer immunotherapy.
Reference
Fitzpatrick R et al. Hip osteoarthritis is not a risk factor for immune checkpoint inhibitor-induced inflammatory arthritis. J Rheumatol. 2026;DOI: 10.3899/jrheum.2025-0808.
