Skip to main content

Table 3 Internal consistency reliability, concurrent validity, and construct validity at baseline

From: Psychometric validation of the visual function questionnaire-25 in patients with diabetic macular edema

  Internal-consistency reliability Concurrent validity Construct validity
   EQ-5D VAS Study eye: ETDRS total letters Fellow eye: ETDRS Total letters Study eye: ETDRS 73–64 letters Study eye: ETDRS 52–35 letters  
VFQ-25 domain Cronbach’s alpha* Pearson correlation Mean ± SD P value from student’s t-test
1. General Health N/A 0.43 0.19 0.10 41.0 ± 24.17 33.5 ± 22.07 .078
2. General Vision N/A 0.30 0.31 0.29 60.3 ± 15.27 46.4 ± 15.95 <.001
3. Ocular Pain 0.70 0.20 0.10 0.01 78.9 ± 23.67 76.1 ± 24.49 .52
4. Near Activities 0.73 0.36 0.35 0.36 65.8 ± 21.93 45.1 ± 21.55 <.001
5. Distance Activities 0.58 0.33 0.34 0.36 70.9 ± 23.44 51.2 ± 23.99 <.001
6. Social Functioning 0.64 0.33 0.31 0.34 84.8 ± 19.51 69.1 ± 27.40 <.001
7. Mental Health 0.78 0.35 0.33 0.30 65.3 ± 24.96 44.8 ± 27.62 <.001
8. Role Difficulties 0.77 0.16 0.27 0.23 59.4 ± 30.67 44.1 ± 26.40 .004
9. Dependency 0.85 0.37 0.34 0.34 78.0 ± 26.40 55.6 ± 33.39 <.001
10. Driving 0.75 0.34 0.41 0.51 65.5 ± 32.09 31.8 ± 33.52 <.001
11. Colour Vision N/A 0.19 0.18 0.14 87.7 ± 19.16 81.8 ± 24.49 .14
12. Peripheral Vision N/A 0.19 0.26 0.36 75.4 ± 25.83 61.4 ± 25.14 .003
VFQ-25 Composite 0.92 0.38 0.39 0.40 72.1 ± 17.91 56.1 ± 18.00 <.001
  1. * Cronbach’s alpha is only applicable for multi-item scales.