[A Comparative Study of Results Based on Changes in the Health Survey Method of the Korea National Health and Nutrition Examination Survey].

Objectives: To improve survey efficiency and reduce the burden on respondents, the Korea National Health and Nutrition Examination Survey (KNHANES) transitioned selected Health Interview Survey items from face-to-face interviews to a self-administered format by 2022 for respondents aged 19 to 60 years. This study evaluates the impact of this methodological change by analyzing data from 2021 and 2022, focusing on seven health indicators among the 24 items affected by the transition. Methods: Survey participants were divided into two groups: those under 60 years of age, who completed self-administered online surveys, and those aged 60 years and older, who participated in face-to-face interviews. We performed comparative analyses using the Rao-Scott chi-square test and t-test to assess differences across survey years. Results: Findings showed that the monthly sickbed experience and annual hospitalization rates remained stable over the years, while activity limitation rates increased in both age groups. In the group under 60, outpatient utilization and influenza vaccination rates declined, whereas unmet medical needs and monthly absence rates increased. These changes were not observed in the group aged 60 and over. Notably, similar trends emerged in health screening rates, despite no changes in survey methodology, indicating that some differences may stem from external factors rather than the survey mode alone. Conclusions: Differences in the 2022 survey results for respondents under 60 years of age reflect both methodological changes and socio-environmental factors compared to 2021. The self-administered method resulted in lower non-response rates, indicating greater efficiency, but also posing potential risks of misinterpretation. Structural improvements to the questionnaire and ongoing monitoring are essential to maintaining the validity, reliability, and consistency of KNHANES data.