Are doctors familiar with the test characteristics of lung cancer screening?

BACKGROUND: Screening with low-dose CT scan can prevent three deaths due to lung cancer among 1000 high-risk individuals. However, false-positive results and radiation exposure are relevant disadvantages deserving accurate consideration. Candidates for screening can only make an autonomous decision if doctors inform them correctly about the pros and cons of the method. Therefore, this study aims to evaluate, whether doctors understand the test characteristics of lung cancer screening. METHODS: In a randomized trial, 556 doctors (members of the Austrian Respiratory Society) were invited to answer questions regarding lung cancer screening based on online case vignettes. Half of the participants were randomized to the group 'with solutions' and received the correct solutions in advance. The group 'without solutions' had to rely on prior knowledge or estimate. Primary endpoint was the between-groups difference in the estimated number of deaths preventable by screening. Secondary endpoints were the between-groups differences in prevalence of lung cancer, prevalence of suspicious results, sensitivity, specificity, positive-predictive value, and false negative rate. Estimations were also compared to actual values from the literature. RESULTS: The response rate was 29 % in both groups (80 'without solutions', 81, 'with solutions', respectively). Reduction of number of deaths due to screening was overestimated six-fold (95%CI: 4-8) with no effect of group allocation. Providing the correct solutions to doctors had no systematic effect on their answers. Compared to actual values from the literature the prevalence of lung cancer was overestimated three-fold, while the prevalence of suspicious results, specificity, positive-predictive value, and false-negative rate were underestimated. CONCLUSIONS: Doctors poorly understand the test characteristics of lung cancer screening. Offering the correct solutions in advance did not improve the answers. Continuing education about lung cancer screening as well as interpretation of test characteristics might be simple remedies.