Moderating effect of health literacy on the association between household income and nonparticipation in oral health examinations among adults: a comparison between urban and rural areas

Objectives: This study examined the association between household income and nonparticipation in oral health examinations among adults and investigated whether the moderating effect of health literacy differed in urban and rural areas. Methods: Data from 230,684 adults aged 19 years or older who participated in the 2025 Korea Community Health Survey were analyzed. We performed complex-sample cross-tabulation and logistic regression analyses using kstrata as the stratification variable, SPOT_NO as the primary sampling unit, and wt_p as the individual sampling weight. A sensitivity analysis was conducted after excluding respondents who reported not seeking health information or not paying attention to written health information. Results: The weighted prevalence of nonparticipation in oral health examinations was 41.4%. Lower household income, limited health literacy, and rural residence were associated with higher odds of nonparticipation. Although the three-way interaction among household income, health literacy, and residential area was significant in the primary analysis (χ²=10.810, p=0.013), it was not significant in the sensitivity analysis (χ²=6.248, p=0.100). Conclusions: Lower household income, limited health literacy, and rural residence were associated with higher odds of nonparticipation in oral health examinations. The difference in this moderating effect between urban and rural areas did not remain significant in the sensitivity analysis and should therefore be interpreted cautiously.