Figure 1. Mortality in Randomized Controlled Trials of Lung Cancer Screening with Chest Radiography with or without Sputum Cytology (Text Description)

Figure 1 represents the relative risks and 95% confidence intervals for mortality outcomes in randomized controlled trials of lung cancer screening with chest radiography with or without sputum cytology. A footnote to the title further explains that followup ranged from 3 to 20 years among the 6 studies. The top of the figure has the text, "Relative risk," with "95% confidence interval" written below it. (Confidence interval has been described as the range of two values within which it is probable that the true value lies for the whole population of participants from whom the study participants were selected. Relative risk has been described as the ratio of the risk of an event among an exposed population to the risk among the unexposed.)

Six studies are listed down the left side of the diagram. Each has a corresponding relative risk rate data point represented by a variably sized black box, on a horizontal line, directly across from the name of the study. The solid black square size represents Mantel-Haenszel weight (represented in a footnote at the bottom of the figure). The data point is representative of the relative risk rate, listed on a horizontal line at the bottom of the figure (y axis), ranging from .5 on the far left, to 2.0 on the far right. A vertical line cuts down the middle of the figure ending at the 1.0 on the relative risk line. Data points fall either to the left or the right of the vertical 1.0 relative risk rate line. (A data point on the left side, or lower than 1.0, represents a decreased risk, while a data point on the right side, or greater than 1.0, represents an increased risk.)

The 6 studies, and their black box size compared to each other (e.g., 1-6, 1=largest, 6=smallest) and orientation related to the vertical 1.0 relative risk line, are as follows:

Study 1. Northwest London Mass Radiography Service Study, 1968, 4 for black box, left side of line.
Study 2. Kaiser Permanente Study, 1979 with data point, 6 for black box, right side of line.
Study 3. Memorial Sloan-Kettering, 1984 with data point, 3 for black box, left side of line.
Study 4. Johns Hopkins Study, 1982 with data point, 5 for black box, left side of line.
Study 5. Mayo Lung Project, 2000 with data point, 1 for black box, right side of line.
Study 6. Czech Study, 2000 with data point, 2 for black box, right side of line.

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