ICI-aOA (total=36)
| Gender | |
| Female | 17 (47.2%) |
| Male | 19 (52.8%) |
| Race/ethnicity | |
| Caucasian | 34 (94.4%) |
| African–American | 1 (2.8%) |
| American–Indian | 1 (2.8%) |
| Age | |
| Mean age at ICI-aOA diagnosis (range) | 66 (51–81) |
| Mean age at cancer diagnosis (range) | 63 (43–79) |
| Cancer type | |
| Melanoma | 10 (27.8%) |
| NSCLC | 5 (13.9%) |
| RCC | 6 (16.7%) |
| Urothelial cancer | 6 (16.7%) |
| Gynecological malignancy | 3 (8.3%) |
| Head and neck | 2 (5.6%) |
| Others | 4 (11.1%) |
| ICI type | |
| CTLA-4i | 0 (0.0%) |
| PD-1/PD-L1i | 31 (86.1%) |
| Combination | 5 (13.9%) |
| Size of joints involved | |
| Large (knees and hips) | 19 (52.8%) |
| Small (first CMCs, DIPs and PIPs) | 9 (25.0%) |
| Spine | 5 (13.9%) |
| Small and large | 3 (8.3%) |
| Number of joints involved | |
| Single | 7 (19.4%) |
| Multiple | 24 (66.7%) |
| Spine | 5 (13.9%) |
| Severity of arthritis (CTCAE) | |
| Grade 1 | 19 (52.8%) |
| Grade 2 | 14 (38.9%) |
| Grade 3 | 3 (8.3%) |
| Presence of other irAEs | |
| Yes | 21 (58.3%) |
| No | 15 (39.5%) |
| Any serological positivity (serology checked in 27 of 36 total patients) | |
| Yes | 11 (40.7%) |
| Antinuclear antibody (7/22) | |
| RF (3/27) | |
| CCP (3/24) | |
| RF and/or CCP (5/27) | |
| No | 16 (59.3%) |
| Cancer outcome | |
| Complete response | 16 (44.4%) |
| Partial response | 5 (13.9%) |
| Stable disease | 11 (30.6%) |
| Progressive disease | 4 (11.1%) |
| ICI-aOA treatment | |
| Local CSI only | 16 (44.4%) |
| NSAIDs only | 7 (20.0%) |
| Physical therapy only | 7 (20.0%) |
| Systemic corticosteroids | 1 (11.4%) |
| Systemic and local corticosteroids | 3 (8.6%) |
| Other agents (acetaminophen, duloxetine and muscle relaxant) | 3 (8.6%) |
| Viscosupplementation | 2 (5.7%) |
| Steroid-sparing agent (HCQ) | 1 (2.9%) |
| ICI-aOA outcome | |
| Improved or stabilized | 32 (88.9%) |
| Worsened | 4 (11.1%) |
| Time of symptom onset and clinical follow-up | |
| Median time of symptom onset after ICI start | 5.2 months (IQR 2–11.4, range 0–33.8) |
| Median length in rheumatology clinic follow-up | 1.6 months (IQR 0–7, range 0–27) |
CCP, cyclic citrullinated peptide; CMC, carpometacarpal joint; CSI, corticosteroid injection; CTCAE, Common Terminology Criteria for Adverse Events; CTLA-4i, cytotoxic T lymphocyte-associated protein 4 inhibitor; DIP, distal interphalangeal joint; HCQ, hydroxychloroquine; ICI, immune checkpoint inhibitor; ICI-aOA, ICI-activated osteoarthritis; irAE, immune-related adverse event; NSAID, non-steroidal anti-inflammatory drug; NSCLC, non-small cell lung carcinoma; PD-1/PD-L1i, programmed cell death protein 1 or programmed cell death protein ligand 1 inhibitor; PIP, proximal interphalangeal joint; RCC, renal cell carcinoma; RF, rheumatoid factor.