The Effect of False-Positive Results on Subsequent Participation in Chest X-ray Screening for Lung Cancer

Background: High attendance rates and regular participation in disease screening programs are important contributors to program effectiveness. The objective of this study was to examine the effects of an initial false-positive result in chest X-ray screening for lung cancer on subsequent screening participation. Methods: This historical cohort study analyzed individuals who first participated in a lung cancer screening program conducted by Yokohama City between April 2007 and March 2011, and these participants were retrospectively tracked until March 2013. Subsequent screening participation was compared between participants with false-positive results and those with negative results in evaluation periods between 365 (for the primary outcome) and 730 days. The association of screening results with subsequent participation was evaluated using a generalized linear regression model, with adjustment for characteristics of patients and screening. Results: The proportions of subsequent screening participation within 365 days were 12.9% in 3132 participants with false-positive results and 6.7% in 15 737 participants with negative results. Although the differences in attendance rates were reduced with longer cutoffs, participants with false-positive results were consistently more likely to attend subsequent screening than patients with negative results (P < 0.01). The predictors of subsequent screening participation were false-positive results (risk ratio [RR] 1.72; 95% confidence interval [CI], 1.54-1.92), older age (RR 1.17; 95% CI, 1.11-1.23), male sex (RR 1.46; 95% CI, 1.29-1.64), being a current smoker (RR 0.80; 95% CI, 0.69-0.93), current employment (RR 0.79; 95% CI, 0.70-0.90), and being screened at a hospital cancer center (vs public health centers; RR 1.36; 95% CI, 1.15-1.60). Conclusions: Our findings indicated that subsequent participation in lung cancer screening was more likely among participants with false-positive results in an initial screening than patients with negative results.