Discordance Between Perceived Health Information Competence and Cancer Prevention Knowledge in U.S. Adults: A Cross-Sectional Study

Background: Self-reported confidence in health information seeking does not reliably predict accurate health knowledge, yet the population-level distribution of this discordance and its demographic predictors have received limited direct study. This study aimed to identify and characterize a Confident-Incorrect phenotype among U.S. adults: individuals with high perceived health information competence who simultaneously hold inaccurate or fatalistic beliefs about cancer. Methods: Cross-sectional analysis of HINTS 7 (N = 7,278). A Confidence Index (3-item digital literacy composite (Cronbach's = 0.674) and an Evidence-Consistent Knowledge Score (factual cancer knowledge minus a cancer fatalism composite; fatalism subscale = 0.563) were computed and combined into a discordance framework. Median-split classification produced four phenotypes. Gaussian Mixture Model clustering with four components provided moderate independent validation (inter-method agreement = 65.2%). Survey-weighted multinomial logistic regression (n = 5,771; McFadden pseudo-R2 = 0.129) examined phenotype predictors. Results: An estimated 20.3% of U.S. adults were classified as Confident-Incorrect. They reported confidence levels similar to Well-Informed adults (z = 0.72 vs. 0.82) but scored 2.8-fold lower on objective cancer knowledge (0.74 vs. 2.06 out of 4) and exhibited the highest cancer fatalism of any phenotype (3.17 vs. 1.65 out of 4). Only 14.3% correctly identified alcohol as a cancer risk factor (vs. 58.8% of Well-Informed adults). Cancer screening rates did not differ meaningfully across phenotypes. Lower education (OR = 0.754), Hispanic ethnicity (OR = 1.788), non-Hispanic Black race (OR = 1.893), higher social media use (OR = 1.097), and lower trust in scientists (OR = 0.749) independently predicted Confident-Incorrect membership. Conclusions: An estimated one in five U.S. adults is overconfident in health information competence while holding substantially inaccurate beliefs about cancer prevention. Cancer screening rates did not follow the expected gradient across phenotypes, a null finding that cautions against inferring immediate behavioral impact from observed belief gaps. Interventions targeting specific factual errors and cancer fatalism are more likely to reach this group than general health literacy programs.