Health Insurance Type and Lung Cancer Stage Shift Following Coverage of Screening

OBJECTIVE: To examine the role of insurance coverage of lung cancer screening in driving shifts in lung cancer stage at diagnosis. STUDY SETTING AND DESIGN: We performed difference-in-differences (DID) analyses to compare changes in the proportion of early-stage lung cancer diagnosis between pre-coverage (2007-2014) and post-coverage (2015-2019) periods across insurance groups. DATA SOURCES AND ANALYTIC SAMPLE: Using the National Cancer Institute's Surveillance, Epidemiology, and End Results database, we identified patients with non-small cell lung cancer aged 55-77 years and diagnosed between 2007 and 2019. Health insurance at diagnosis was categorized as private, Medicare (fee-for-service [FFS], FFS with supplemental private coverage, FFS with Medicaid, and Medicare Advantage with and without Medicaid), Medicaid (FFS and managed care), military health plans, and uninsured. PRINCIPAL FINDINGS: Among 227,112 patients, 63,676 (28.04%) had private insurance, 130,770 (57.58%) Medicare, 14,982 (6.60%) Medicaid, 5941 (2.62%) military health insurance, and 11,743 (5.17%) were uninsured. Compared with uninsured patients, a significantly greater increase in the proportion of early-stage lung cancer diagnosis between pre-coverage and post-coverage periods was observed among Medicaid patients (DID = 2.88 percentage points [ppt], 95% CI 0.73-5.02 ppt), but not patients with private insurance, Medicare, or military health insurance. Among Medicaid beneficiaries, those in managed care showed a significantly greater shift compared with those in FFS during 4-5 years post-coverage (DID = 8.22 ppt, 95% CI 4.51-11.93 ppt). Among Medicare FFS beneficiaries, dual enrollment in Medicaid was associated with a significantly smaller increase in the proportion of early-stage diagnosis compared with FFS-only enrollment during 4-5 years post-coverage (DID = -4.40 ppt, 95% CI [-6.40]-[-2.40] ppt). CONCLUSIONS: The results suggest that beneficial stage shifts following the recommendation for lung cancer screening varied by health insurance status and type. Addressing patient, provider, and system-level barriers to lung cancer screening and downstream care is essential to translate lung cancer screening coverage into earlier-stage diagnosis.