Adherence to CT screening and follow-up by Lung-RADS category: A multicenter cohort study

Background: Timely screening and follow-up care are critical for reducing lung cancer mortality. However, adherence to low-dose computed tomography (LDCT) or any CT screening and guideline-recommended follow-up remains poor in real-world practice after the baseline scan. The objective of this study is to identify factors associated with adherence across Lung-RADS negative and positive categories. Methods: We conducted a retrospective, multi-site cohort study of adults aged 55-74 who underwent LDCT between 2016 and 2020, had ≥1 primary care visit before baseline, and had no lung cancer diagnosis in the prior 5 years. Adherence definitions followed Lung-RADS management guidelines. We fit mixed-effects logistic regression models with a random intercept for site, estimated using adaptive Gauss-Hermite quadrature (QPOINTS=7). Results: Of 31,795 patients, 6279 were excluded, leaving 21,275 Lung-RADS negative (1-2) and 4,241 Lung-RADS positive (3-4X) patients. Adherence was low in both groups: 21.3% for Lung-RADS 1-2 and 28.6% for Lung-RADS 3-4X. Among Lung-RADS 1-2 patients, adherence was higher among those aged ≥65 (OR 1.19; 95% CI 1.10-1.28) compared with <65 years, and those with COPD (OR 1.15; 95% CI 1.06-1.24), but lower among Black patients compared with White patients (OR 0.87; 95% CI 0.78-0.96) and never smokers compared with current smokers (OR 0.65; 95% CI 0.53-0.79). Among Lung-RADS 3-4X patients, COPD remained positively associated with adherence (OR 1.19; 95% CI 1.03-1.39), while pre-frailty was associated with lower adherence compared with non-frail status (OR 0.80; 95% CI 0.66-0.98). Most other sociodemographic and contextual factors were not statistically significant in adjusted models. Conclusions: Adherence to any CT screening after negative results and recommended follow-up after positive findings remains poor. Age, race, smoking behavior, COPD, and frailty-related vulnerability contribute to adherence patterns, highlighting the need for targeted, patient-centered strategies to improve retention and follow-up in real-world screening programs. Keywords: Lung-RADS, adherence, follow-up, lung cancer