AbstractBackgroundThe programmed cell death protein 1 (PD‐1) inhibitor, as one of the immune checkpoint inhibitors (ICIs), is the standard treatment for advanced lung cancer. However, immune‐related adverse events (irAEs) remain poorly understood toxicities. It is unclear whether frailty plays a role in the occurrence of irAEs. Thus, we assess whether irAEs occur more often in frail patients than in non‐frail patients according to the Frailty Index (FI).MethodsA retrospective study was conducted. Medical records from lung cancer patients treated with PD‐1 inhibitors (Sintilimab, Camrelizumab, Tislelizumab, and Pembrolizumab) at Peking University First Hospital (May 2018–June 2022). Patients were categorized into non‐frail and frail groups according to a cut‐point of 0.25 by FI. The FI calculation included 28 baseline variables, all of which were health deficits measured by questionnaires and body measurements.ResultsThe statistical analysis included 114 advanced lung cancer patients. The median age was 66 years, and the male/female ratio was 4.7:1 (94/20). Approximately 39 (34%) were classified as frail. PD‐1 inhibitor‐related adverse events occurred in 17.5% of patients, and 6.1% experienced irAEs of grade ≥3. There was no significant difference in the occurrence of irAEs (14.7% vs. 23.1%,p= 0.26), grade ≥ 3 irAEs (5.3% vs. 7.7%,p= 0.93), and treatment discontinuation due to irAEs (12.0% vs. 17.9%,p= 0.39) between non‐frail and frail patients. However, frail patients are more likely to have more than one type of irAEs and are more possibly to have checkpoint inhibitor pneumonitis (CIP) than non‐frail patients when they use PD‐1 inhibitors (p< 0.05). Frail patients had a longer hospital stay (6 vs. 3 days,p= 0.01).ConclusionsFrailty is not associated with severe irAEs, but is related to CIP. Meanwhile, it predicts more than one type of irAEs and a longer hospital stay. Frailty screening has added value to the decision‐making process for frail patients eligible for PD‐1 inhibitors.