Vertical Integration and Oncologists' Adoption of Immune Checkpoint Inhibitors in Non-Small Cell Lung Cancer.

[OBJECTIVE] To examine the trend in Immune Checkpoint Inhibitor (ICI) use before and after FDA approval in 2015 for patients with metastatic non-small cell lung cancer (NSCLC), and whether vertical integration of oncologists affected ICI use.

[STUDY SETTING AND DESIGN] We conducted a retrospective cohort study of patients with metastatic NSCLC from 21 population-based cancer registries in the United States. We measured whether patients' treating oncologists were vertically integrated based on ≥ 10% of total services billed through hospital outpatient departments. We described the percentage of ICI recipients annually in 2010-2019, stratified by oncologists' integration status each year. In the post-FDA approval period (2015-2019), we used difference-in-differences (DID) modeling to compare the probability of patients' receiving ICI before and after oncologists became integrated relative to those whose oncologists remained non-integrated.

[DATA SOURCES AND ANALYTIC SAMPLE] Using the SEER-Medicare linkage, we identified Medicare Fee-For-Service beneficiaries aged ≥ 65.5 years diagnosed with metastatic NSCLC in 2010-2019 and followed them from diagnosis until ICI receipt, death, or end of 2019.

[PRINCIPAL FINDINGS] The overall percentage of patients receiving ICI increased from 0% before 2015 to 4.0% in 2015, and further increased to 29.2% in 2019. The percent of ICI recipients was higher among integrated (6.9%) than non-integrated oncologists (2.0%, p < 0.001) in 2015, but by 2017 adoption rates converged (19.8% vs. 19.8%, p = 0.91). DID analysis showed non-significant changes in the probability of ICI use after oncologists became integrated (1.7 percentage points, 95% CI = -1.0 to 4.4) relative to oncologists who remained non-integrated.

[CONCLUSIONS] Integrated oncologists were quicker to adopt ICIs in the first year after FDA approval, but this lead was not sustained over time. Vertically integrating into health systems was not associated with significant changes in ICI use. Further research is needed on the factors influencing equitable dissemination of novel cancer therapies across practice settings.