Convergence and divergence between PROMIS® global health and EQ-5D-3L in a national population sample

To compare correlation, agreement, and residual patterns between Patient-Reported Outcomes Measurement Information System (PROMIS) Global Health (GH) and EQ-5D-3 L and to identify areas of convergence and divergence across health domains in a nationally representative Korean population. A total of 2,699 adults completed PROMIS GH and EQ-5D-3 L between December 2021 and January 2022. A linear regression model was used to predict EQ-5D-3 L index values from PROMIS physical and mental health T-score. Agreement between predicted and observed EQ-5D values was assessed using intraclass correlation coefficients (ICC) and root mean squared error (RMSE). Residuals between observed and predicted EQ-5D values were examined to detect systematic discrepancies across demographic, clinical subgroups, and EQ-5D domain severity levels. The relationship between PROMIS GH and EQ-5D showed consistent agreement (RMSE = 0.079). Approximately 9.8% of participants showed large discrepancies (absolute residual > 0.1) between observed and PROMIS-predicted EQ-5D values. Divergence was most pronounced in those with mobility, self-care, or usual activities problems, and poor PROMIS Physical Health was the strongest predictor of large discrepancies (Odds ratio = 3.68). PROMIS GH and EQ-5D-3 L showed overall agreement but also systematic discrepancies across subgroups. Larger differences were observed in individuals with functional limitations, particularly in mobility, self-care, and usual activities domains. These patterns suggest that the two instruments may capture related but not identical aspects of health.