B40-05 Longitudinal Adherence to Annual Lung Cancer Screening With Low-dose Computed Tomography Among Medicare Beneficiaries: A Population-based Study

Rationale Annual lung cancer screening (LCS) with low-dose computed tomography (LDCT) reduces lung cancer mortality among high-risk individuals, but its effectiveness partly depends upon adherence to annual screening and ability to undergo treatment. We evaluated longitudinal adherence to annual LCS among older Medicare beneficiaries who underwent baseline screening, overall and stratified by a claims-based frailty measure. Methods We conducted a retrospective cohort study of individuals, aged ≥66 years, who received a first LCS between 2015 and 2019, with no prior history of lung cancer, using Medicare fee-for-service claims. Annual adherence was defined as receipt of a subsequent LDCT screening within 11 to 15 months from the first screen, as this represents a reasonable window for determining adherence to annual LCS. We estimated cumulative incidence functions (CIFs) over months since baseline LDCT using Aalen-Johansen estimator, treating lung cancer diagnosis and death as competing events. Cumulative incidence plots were estimated overall and stratified by frailty. Frailty was assessed using the Medicare claims-based Faurot frailty index (FFI), categorized as low (FFI<0.05), low-medium (0.05≤ FFI<0.10), medium (0.10≤FFI<0.20), medium-high (0.20≤FFI< 0.40), and high (FFI≥0.40). Results Among 54,978 Medicare beneficiaries who received an initial LDCT, the mean age was 70.8 years (standard deviation [SD] 3.26) and 50.5% were female. Most individuals had low frailty (81.0%); 11.3% were low-medium, 4.7% medium, 1.9% medium-high, and 1.0% high. The cumulative incidence of subsequent LCS with LDCT was 4.3% (95% CI: 4.1-4.5%) at 11 months, 31.1% (95% CI: 30.7-31.6%) at 15 months, with an annual adherence of 26.8% (95% CI: 26.3-27.3%) between 11 and 15 months. Adherence to LCS decreased with increasing FFI: 27.6% (95% CI: 27.0-28.1%) in low, 23.6% (95% CI: 22.3-25.0%) in low-medium, 21.9% (95% CI: 20.0-24.0%) in medium, 18.9% (95% CI: 15.7-22.0%) in medium-high, and 16.6% (95% CI: 13.0-20.3%) in high frailty groups. The cumulative incidences of lung cancer and death at 15 months were 2.1% (95% CI: 2.0-2.2%) and 2.9% (95% CI: 2.7-3.0%), respectively. Conclusion Longitudinal adherence to annual LCS with LDCT remains suboptimal among Medicare beneficiaries, with fewer than one-third undergoing subsequent screening within 15 months. Adherence was lower for those with higher FFI and highlights a need to align screening practices with health status and clinical context among older adults, to optimize benefits and minimize harms among frail populations. This abstract is funded by: NATIONAL CANCER INSTITUTE