Association between phase angle and self-rated health among Korean adults: a cross-sectional analysis from the 2022–2023 KNHANES

Self-rated health (SRH) is a well-established predictor of morbidity and mortality, whereas phase angle (PA) reflects physiological health. This study examined the association between PA and SRH in Korean adults. The specific objectives were to: (1) estimate the relationship between PA and SRH in a nationally representative dataset; (2) determine whether this association differs by sex; and (3) assess whether age modifies the PA–SRH association.

This cross-sectional study used data from 8470 adults aged  ≥ 19 years participating in the 2022–2023 Korea National Health and Nutrition Examination Survey. SRH was assessed using a single global health question, and PA was measured under standardized conditions. Generalized linear models with a logit link were used to estimate odds ratios (ORs) for poorer SRH per 1° increase in PA, adjusting for sociodemographic, clinical, and lifestyle factors. Interaction terms were tested for sex and age group. Sensitivity analyses using multiple imputation addressed missing data.

Higher PA was associated with lower odds of reporting poorer SRH (OR per 1° increase, 0.78; 95% CI: 0.72–0.84). No significant PA × sex interaction was observed (p = 0.735). Age significantly modified the association (p for interaction < 0.001), with the strongest association in adults aged ≥ 60 years (OR, 0.71; 95% CI: 0.63–0.80).

Higher PA was associated with better SRH in Korean adults, with stronger associations observed in older individuals. These exploratory findings suggest that combining subjective and objective indicators, such as SRH and PA, may be informative for future research on population health.