Psychosocial consequences of false positives in the Danish Lung Cancer CT Screening Trial: a nested matched cohort study

Objectives Lung cancer CT screening can reduce lung cancer mortality, but high false-positive rates may cause adverse psychosocial consequences. The aim was to analyse the psychosocial consequences of false-positive lung cancer CT screening using the lung cancer screening-specific questionnaire, Consequences of Screening in Lung Cancer (COS-LC). Design and setting This study was a matched cohort study, nested in the randomised Danish Lung Cancer Screening Trial (DLCST). Participants Our study included all 130 participants in the DLCST with positive CT results in screening rounds 2-5, who had completed the COS-LC questionnaire. Participants were split into a true-positive and a false-positive group and were then matched 1:2 with a control group (n=248) on sex, age (+/- 3 years) and the time of screening for the positive CT groups or clinic visit for the control group. The true positives and false positives were also matched 1:2 with participants with negative CT screening results (n=252). Primary outcomes Primary outcomes were psychosocial consequences measured at five time points. Results False positives experienced significantly more negative psychosocial consequences in seven outcomes at 1 week and in three outcomes at 1 month compared with the control group and the true-negative group (mean Delta score >0 and p<0.001). True positives experienced significantly more negative psychosocial consequences in one outcome at 1 week (mean Delta score 2.86 (95% CI 1.01 to 4.70), p=0.0024) and in five outcomes at 1 month (mean Delta score >0 and p<0.004) compared with the true-negative group and the control group. No long-term psychosocial consequences were identified either in false positives or true positives. Conclusions Receiving a false-positive result in lung cancer screening was associated with negative short-term psychosocial consequences. These findings contribute to the evidence on harms of screening and should be taken into account when considering implementation of lung cancer screening programmes.