Smoking status and adherence to diagnostic follow-up after community-based low-dose CT screening

Background Low-dose computed tomography (CT) screening reduces lung cancer–specific mortality; however, its effectiveness depends on adherence to recommended diagnostic follow-up after abnormal findings. Factors associated with follow-up nonattendance in real-world screening settings remain insufficiently characterized. Methods We conducted a retrospective cohort study using a community-based low-dose CT screening program in Japan (2010–2025). Examinations requiring further evaluation were included (n = 3507). The primary outcome was nonattendance for diagnostic follow-up within 365 days. Multivariable logistic regression models were used to estimate adjusted odds ratios (ORs). In a subcohort with documented follow-up dates (2021–2025; n = 1122), time to follow-up attendance was analyzed using Kaplan–Meier methods and multivariable Cox proportional hazards models. Results Among 3507 examinations requiring further evaluation (mean [SD] age, 67.4 [9.5] years; 73.9% male), 678 (19.3%) had no documented follow-up within 365 days. Current smoking was strongly associated with higher odds of nonattendance compared with former smoking (adjusted OR, 2.15; 95% CI, 1.71–2.70). Respiratory symptoms were associated with lower odds of nonattendance (OR, 0.66; 95% CI, 0.55–0.79). In time-to-event analyses, current smoking was associated with delayed follow-up attendance (adjusted HR, 0.63; 95% CI, 0.52–0.75; P < .001). Suspected disease category was not associated with follow-up nonattendance in the multivariable logistic regression analysis. Conclusions These findings suggest that smoking status may be an important determinant of successful linkage to diagnostic care, highlighting the need for targeted strategies to improve follow-up adherence among participants with current smoking in CT screening programs.