Risk factors for immune checkpoint inhibitor-related interstitial lung disease: a retrospective cohort study

Immune checkpoint inhibitors (ICIs) for cancer treatment show a high incidence of immune-related adverse events (irAEs), among which severe interstitial lung disease (ILD) can be fatal, requiring prompt identification and management. This study aimed to identify pre-treatment risk factors associated with ICI-induced ILD. Medical records of patients who received ICIs were retrospectively reviewed. Age, sex, body weight, primary tumor type, ICI agent, PD-L1 status, disease stage, line of treatment, and laboratory parameters measured before treatment initiation were collected. Smoking history and prior diagnoses of chronic obstructive pulmonary disease and ILD were recorded. Patients who developed ILD were compared with those who did not. Elevated pre-treatment C-reactive protein (CRP) levels (odds ratio [OR] = 1.877; 95% confidence interval [CI] = 1.238-2.845; p = 0.003) and increased monocyte counts (OR = 23.509; 95% CI = 1.375-4.020 × 10²; p = 0.029) were potential risk factors for ILD development following ICI therapy. A multivariable logistic regression model incorporating pre-ICI CRP levels and monocyte counts was constructed to predict ILD risk. The receiver operating characteristic analysis of this model yielded an area under the curve of 0.808 with a sensitivity of 92.0% and a specificity of 63.9%. Elevated pre-treatment levels of CRP and monocytes were significantly associated with the subsequent ILD development in patients treated with ICIs. These findings underscore the importance of close monitoring for pulmonary toxicity in patients with elevated CRP and monocyte counts before initiating ICI therapy.