Table 4.

Risk of irAE after immune checkpoint inhibition, comparing pre-existing RA cases (n=87) to matched non-RA comparators (n=203).

	irAE cases	Person- months	Incidence rate (95%CI) per 1000 person- months	Unadjusted Cox HR (95%CI)	Adjusted Cox HR (95%CI)	Unadjusted competing risk sdHR (95%CI)	Adjusted competing risk sdHR (95%CI)
Outcome: all-grade irAE (co-primary analysis for irAE)
Pre-existing RA cases	53	583	90.9 (66.4, 115.3)	1.63 (1.15, 2.31)	1.72 (1.20, 2.47)	1.85 (1.30, 2.62)	2.02 (1.41, 2.89)
Matched comparators	99	2,475	40.0 (32.1, 47.9)	1.0 (Ref)	1.0 (Ref)	1.0 (Ref)	1.0 (Ref)
Outcome: grade 3+ irAE
Pre-existing RA cases	12	1,394	8.6 (3.7, 13.5)	0.96 (0.49, 1.88)	1.06 (0.53, 2.12)	1.03 (0.52, 2.03)	1.24 (0.60, 2.53)
Matched comparators	30	4,041	7.4 (4.8, 10.1)	1.0 (Ref)	1.0 (Ref)	1.0 (Ref)	1.0 (Ref)
Outcome: all-grade irAE, excluding RA flare and IA
Pre-existing RA cases	26	1,042	25.0 (15.4, 34.5)	0.56 (0.36, 0.87)	0.59 (0.38, 0.92)	0.58 (0.37, 0.92)	0.62 (0.39, 0.98)
Matched comparators	99	2,484	39.9 (32.0, 47.7)	1.0 (Ref)	1.0 (Ref)	1.0 (Ref)	1.0 (Ref)
Outcome: grade 3+ irAE, excluding RA flare and IA
Pre-existing RA cases	11	1,406	7.8 (3.2, 12.5)	0.87 (0.43, 1.74)	0.96 (0.47, 1.96)	0.93 (0.46, 1.87)	1.11 (0.53, 2.32)
Matched comparators	30	4,041	7.4 (4.8, 10.1)	1.0 (Ref)	1.0 (Ref)	1.0 (Ref)	1.0 (Ref)

^*In addition to matching factors of age, calendar year, cancer type, target of ICI, adjusted for smoking pack-years, cancer duration, previous chemotherapy or hormonal therapy, previous radiation, previous stem cell transplant/CAR-T, and continuous Charlson comorbidity index.

CAR-T, chimeric antigen receptor T cells; CI, confidence interval; HR, hazard ratio; IA, inflammatory arthritis; ICI, immune checkpoint inhibitor; irAE, immune-related adverse event; RA, rheumatoid arthritis; sdHR, subdistribution hazard ratio.