Risk factors for immune checkpoint inhibitor–related adverse events in the geriatric lung cancer population.

e20579 Background: Immune checkpoint inhibitors (ICIs) have revolutionized the management of lung cancer, especially for the elderly, who may prefer avoiding chemotherapy-associated toxicities. However, ICIs can lead to immune related adverse events (irAEs). Predicting irAEs in the elderly is crucial to prevent a decline in quality of life and treatment discontinuation. We aim to identify risk factors that may be associated with the incidence of irAEs in geriatric lung cancer patients. Methods: This is a retrospective single-institution cohort study of patients, aged 65 and older, with lung cancer treated with ICIs between 2014-2024. Clinicodemographic variables were collected from the EMR. Systemic immune-inflammation index (SII) was calculated using the formula: platelets x neutrophils/lymphocytes. A univariate and multivariate analysis was conducted to assess risk factors for irAEs. Results: 326 patients were included with a 29.8% incidence of irAE. The most common irAEs were pneumonitis (34%) and thyroiditis (28%). 24% of irAE cases led to hospitalization, and 4% to death. In a univariate and multivariate analysis of biopsychosocial risk factors, the only significant association with irAE incidence was African American (AA) race, which was protective, with OR of 0.27 (95% CI 0.12, 0.69) p=0.001 and OR of 0.21 (CI: 0.06, 0.73) p=0.014, respectively. Other protective factors included: Hispanic ethnicity (OR: 0.65, p= 0.38) and male sex (OR: 0.76, p= 0.26). Factors with an increased risk of irAE included: widowed (OR: 1.84, p= 0.09), single/divorced (OR: 1.26, p= 0.80), > 20 PY smoking history (OR: 1.80, p= 0.14), BMI 25-29.9 (OR: 1.72, p = 0.06), and living alone (OR: 2.10, p= 0.04). Among comorbidities that were univariably assessed as risk factors, GERD was found to be the only significant risk factor with OR of 3.11(CI 1.66, 5.82) p= 0.004 and this was maintained with multivariate analysis OR 3.04 (CI: 1.59, 5.82) p=0.001. Type 2 diabetes was found to be a protective factor for irAE with OR of 0.41 (CI 0.21, 0.78) p= 0.007. Other risk factors evaluated included thyroid disease (OR: 1.25, p= 0.55), hypertension (OR: 1.19, p= 0.55), CAD (OR: 0.74, p= 0.35), and psychiatric disease (OR: 1.48, p= 0.31). Lastly, mean SII at diagnosis showed no significant difference between those who had irAE (1514, std 1304) and those who did not (1895, std 2032) (p = 0.237). Conclusions: Our study suggests that AA race may be protective against irAE and GERD may be a risk factor. SII was not a reliable predictor of irAE incidence. There was a trend towards increased irAE risk in the widowed/single/divorced, >20 PY smoking history, overweight, living alone, and underlying psychiatric disease population. Further research is needed, to inform ICI treatment decisions in older patients. Supportive interventions for patients with psychosocial risk factors should be prioritized.