Table 1.
The nine selected questionnaire items.
A short name (in bold) has been assigned to each item. Response options have been rearranged in the order from most to least favorable outcome
Fig 1.
NA indicates missing responses. Refer to Table 1 for item response descriptions of the digits for each item.
Table 2.
Summary statistics across demographics.
Table 3.
Loevinger’s H coefficients and automated item selection procedure results.
H coefficient standard errors are shown in parentheses. Scalable items are denoted by 1 at a given threshold, while 0 indicates the item was unscalable.
Table 4.
Factor loadings (F1 and F2), Communalities (h2), Uniquenesses (u2), and Complexity (com) from EFA with Oblimin Rotation.
Loadings < 0.20 are omitted for clarity.
Table 5.
Model fit statistics for IRT models.
Table 6.
Bifactor GRM item parameters (intercept parameterization) and general–axis thresholds.
Values are estimates with SE in parentheses. ajg = general factor slope; ajs1 = Physical Functioning specific slope; ajs2 = Well-being/Mental Health specific slope. General–axis thresholds are computed with specific factors fixed at 0.
Fig 2.
Expected item scores vs. frailty score () by age group, sex and education.
The expected item score reflects a weighted average of possible responses based on their estimated probabilities.
Table 7.
ESSD for each item across grouping variables.
Table 8.
Estimated latent means and variances (±95% CI) for all groups.
Fig 3.
Kaplan–Meier survival curves stratified by quartile.
Quartiles Q1–Q4 correspond to increasing (worse recovery); shaded bands are 95% CIs and vertical lines are events (death).
Table 9.
Cox regression modeling hazard of death utilizing frailty (θ) scores from unidimensional and bifactor (general-factor θ scores) IRT models are shown in their respective columns.
Age and θ scores were centered before fitting the Cox models for easier main effect interpretation.