Occurrence of Possible Rheumatologic Immune-Related Adverse Events (rh-irAEs) Associated with Immune Checkpoint...

Area of Science:

• Oncology
• Immunology
• Rheumatology

Background:

• Limited epidemiologic data exists for rheumatologic immune-related adverse events (rh-irAEs).
• Previous studies relied on clinical trials, case reports, or small, single-center series.
• This study analyzes rh-irAEs during immune checkpoint inhibitor (ICI) therapy using US commercial claims data.

Purpose of the Study:

• To evaluate the occurrence of rh-irAEs in patients receiving ICI therapy.
• To compare rh-irAE incidence between patients with and without pre-existing rheumatic disease.
• To identify the types of rh-irAEs and the role of rheumatologist involvement.

Main Methods:

• Retrospective analysis of US commercial claims data for patients initiating ICI therapy.
• Identification of rh-irAEs using ICD-9 or ICD-10-CM codes for specific rheumatologic conditions and symptoms.
• Comparison of rh-irAE rates based on prior rheumatic disease history and rheumatologist claims.

Main Results:

• Among 5521 patients without prior rheumatic disease, 29.6% experienced rh-irAEs.
• In patients with pre-existing rheumatic disease (n=201), 71.6% experienced rh-irAEs.
• Claims with a rheumatologist provider showed a significantly lower incidence (0.9%) of rh-irAEs.

Conclusions:

• Patients with pre-existing rheumatic disease have a higher incidence of rh-irAEs during ICI therapy.
• Many reported events were symptoms (e.g., joint pain) rather than confirmed rheumatic diseases.
• The low rate of rh-irAEs associated with rheumatologist providers suggests potential issues with referral or diagnostic confirmation.