Factors Associated With the Use of Immune Checkpoint Inhibitors in Older Adults With Metastatic Non-Small Cell Lung Cancer and Pre-Existing Autoimmune Disease: A SEER-Medicare Study

OBJECTIVES: The presence of pre-existing autoimmune disease (PAD) with metastatic non-small cell lung cancer (mNSCLC) poses challenges in the use of immune checkpoint inhibitors (ICIs). This study investigates factors influencing ICI utilization in older adults with mNSCLC and PAD.

METHODS: A retrospective cohort study with a 12-month baseline prior to treatment initiation was conducted using the SEER-Medicare data. Patients aged 66 years and above diagnosed with mNSCLC from January 2015 to December 2017, who initiated immunotherapy only/chemoimmunotherapy (IT/CIT) or chemotherapy only (CIT) were included. Multiple factors, guided by the Model of Health Services Utilization proposed by Andersen and Newman, were analyzed using multivariable logistic regression. Adjusted odds ratios (aORs) and 95% CIs were reported. Statistical significance was set at p<0.05, and SAS 9.4 was used for all analyses.

RESULTS: Among 1,319 patients initiating first-line (1L) systemic treatment, 22.28% received IT/CIT, and 77.71% received CT. Patients initiating IT/CIT were more likely to be 76-80 years old (aOR=1.695, 95%CI=1.023-2.808) and >80 years old (aOR=2.491, 95%CI=1.459-4.253), residing in South (aOR=2.324, 95%CI=1.363-3.964) and West (aOR=2.272, 95%CI=1.436-3.595) SEER regions, diagnosed in 2016 (aOR=6.360, 95%CI=3.060-13.220) and 2017 (aOR=40.454, 95%CI=19.702-83.065), having longer time to treatment initiation (aOR=1.136, 95%CI=1.081-1.194), having non-squamous tumor histology (aOR=1.511, 95%CI=1.048-2.179), and having a prior hospitalization (aOR=1.625, 95%CI=1.136-2.325). These patients were less likely to have recent immunosuppressant (IS) use (aOR=0.062, 95%CI=0.037-0.103).

CONCLUSIONS: Several factors, such as age, region, cancer diagnosis year, time to treatment initiation, and recent IS use, intricately shape treatment decisions. Further in-depth research on each of these factors is imperative to optimize strategies for this distinctive patient population.