PD-1 Immune Checkpoint Inhibitors and Immune-Related Adverse Events: a Cohort Study

This observational, retrospective cohort study will evaluate the risk of immune-related adverse events associated with PD-1 inhibitors use compared to standard chemotherapy use in patients with non small cell lung cancer, using nationwide healthcare database. PD-1 inhibitors will be defined as nivolumab, pembrolizumab, and atezolizumab. Standard chemotherapy will be defined as cytotoxic chemotherapy or tyrosine kinase inhibitors (epidermal growth cell receptor (EGFR) and anaplastic lymphoma kinase (ALK) inhibitors). The investigators will assess exposure on the cohort entry using the intention-to-treat approach with the 6-month exposure risk window from the first PD-1 inhibitor prescription to avoid bias from informative censoring. Immune-related adverse events will be defined by using pre-specified algorithms using diagnosis and corticosteroid prescription records (high dose of oral corticosteroids, defined as ≥ 30 mg/day, or systemic corticosteroid injection) to reduce outcome misclassification. The investigators will use a multivariable Cox proportional hazard model to estimate hazard ratio (HR) and 95% confidence intervals (CI). The model will be adjusted for pre-existing autoimmunity, history of lung cancer surgery, radiation therapy, tyrosine kinase inhibitor use, and previous systemic corticosteroid use. All analyses will be undertaken using SAS 9.4 (SAS Institute Inc., Cary, NC, USA).