Figure 1. Efficacy of Low-Dose CT Screening, According to Risk Quintile.

Panel A shows the lung-cancer mortality ratio for the low-dose CT group versus the radiography group among risk quintiles 1 through 5 (Q1 through Q5, each 20% of the screening group) for the prescreening 5-year risk of lung-cancer death. Panel B shows the number of lung-cancer deaths prevented by low-dose CT (i.e., the between-group difference) among the risk quintiles. The exact boundaries for the risk of 5-year lung-cancer death for each quintile, as percentages, are shown on the x axis. Bars denote 95% confidence intervals. The horizontal gray lines indicate the overall efficacy of low-dose CT screening. The gray symbols indicate the efficacy outcomes in risk quintiles as defined by four published prediction models of lung-cancer incidence: Bach et al.,²³ Spitz et al.,²⁴ Cassidy et al. (for the Liverpool Lung Project [LLP]),²⁵ and Tammemagi et al.²⁶