Table 4 Comparison of psychometric properties and diagnostic accuracy of the GFI-C with previously published results

Reliability

 Internal consistency

Cronbach's α = 0.87

Cronbach's α = 0.68

 Stability

ICC = 0.87, p < 0.001 (95% CI = 0.78–0.92)

r = 0.939 (p < 0.001)^b

Validity

 Face validity

100% acceptable

84% of older persons had no difficulty completing the GFI

 Content validity

CVI = 0.98

I-CVI = 0.83–1.0; S-CVI = 0.98 (S-CVI/UA = 0.66)^c

 Criterion-related validity

r = 0.76, p < 0.001

–

 Construct validity

 1. Known-groups method

t = 8.71, p < 0.001 (95% CI = 2.95–4.52)

Statistically significant

 2. Hypothesis testing

  Correlation with GFI-C and AMT score

r = −0.77, p < 0.001

The correlations for the convergent (0.45–0.61) and discriminant validity (0.08–0.50) were also as hypothesised.

  Correlation with GFI-C and SBI score

r = − 0.67, p < 0.001

 3. Factor analysis

χ²/df = 2.87, TLI = 0.92,

CFI = 0.93, GFI = 0.92,

RMR = 0.014, RMSEA = 0.073

χ² = 235.02, df = 84, (p < 0.00001), GFI = 0.98, RMR = 0.0063, RMSEA = 0.074^b

Diagnostic accuracy

 Sensitivity for frailty

Cut-off value ≥3

Sensitivity = 88.2%

(95% CI: 81.8–93.0%)

Cutoff value ≥4, Sensitivity = 66%

(95% CI: 56–75%)^d

 Sensitivity for pre-frailty

Cut-off value ≥2

Sensitivity = 71.5%

(95% CI: 65.9–76.6%)

Nil

 Specificity for frailty

Cut-off value ≥3

Specificity = 79.6%

(95% CI: 73.5–84.9%)

Cutoff value ≥4, Specificity = 87%

(95% CI: 76–94%)^d

 Specificity for pre-frailty

Cut-off value ≥2

Sensitivity = 84.7%

(95% CI: 73.0–92.8%)

Nil