Objectives The USPSTF recommends shared decision making to help patients understand the benefits and harms of lung cancer screening (LCS), and Medicare requires a decision aid, including information on over-diagnosis, to facilitate this discussion. Whether LCS decision aids improve knowledge of benefits and harms, particularly over-diagnosis, is not well known. We examined the effect of a LCS decision aid on knowledge in a screen-eligible population (current or former smokers who quit less than 15 years ago, aged 55–80 with >30 pack-years of smoking) and whether knowledge scores differ across demographic groups.

Method We conducted a web-based survey of screen-eligible participants recruited though US online panels, and performed a single group pre-post experiment using a previously developed and validated, brief (3 minute) multi-media LCS decision aid. Participants answered 10 previously validated questions about key potential benefits and harms of screening, focusing on over-diagnosis.

Result Among 269 USPSTF-eligible respondents who began the survey, 185 (62.5%) completed it. Respondents were 56.2% female, 80.5% white, 60.5% current smokers, 30.3% high school degree or less, 62.2% annual income <$50,000, and 73.0% Medicare, Medicaid or military insurance. Baseline overall knowledge scores (0–10 scale) were low and increased following decision aid viewing: (mean pre-decision aid knowledge score 2.8 vs 5.4 post-decision aid, diff 2.5, 95%CI 2.1, 2.9, p<0.001). Proportions of respondents able to correctly identify the likelihood of benefiting from screening increased after decision aid viewing (pre 16.2% vs. post 39.5%, p<0.001). Respondents correct on the over-diagnosis specific question, ‘Screening leads some people with a harmless cancer to get treatment they do not need (True/False/Don’t Know)’ improved significantly (pre 22.2% vs post 70.8%, p<0.001). The proportion of respondents able to more accurately estimate the likelihood of being overdiagnosed with screening also increased (25.4% vs 46.0%, p<0.001). Mean post-decision aid scores did not differ by sex, age (<65yo vs ≥65yo), annual income (<$25,000 vs ≥$25,000) or smoking status (former vs current). Participants with at least some college had higher knowledge scores post decision aid as those with no college (mean post knowledge score: some college 5.7 vs no college 4.7, diff 0.8 95%CI 0.8, 1.6, p=0.030. However, both groups demonstrated similar pre-post gains in knowledge (mean pre-post difference: college +2.5 vs no college +2.6, diff 0.02 95%CI -0.8, 0.8, p=0.501).

Conclusions A brief decision aid substantially increased knowledge about benefits and harms of LCS, including over-diagnosis. Although participants with greater education demonstrated greater overall knowledge after decision aid viewing, both higher and lower education groups experienced similar gains in knowledge. The decision aid was otherwise similarly effective across demographic groups.