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Table 7 Differential item functioning tested for gender

From: Psychometric properties of the Danish Hospital Anxiety and Depression Scale in patients with cardiac disease: results from the DenHeart survey

  OR (95% CI)a
for item responses
1, 2 and 3
Overall
p-value
Significant interaction between gender and sub scale Nagelkerke’s R2
Step 1
Nagelkerke’s R2
Step 2
Nagelkerke’s R2
Step 3
DIF R2 b
HADS-A
 Item 1. I feel tense or ‘wound up’    X 0.6712 0.6714 0.6717 0.0005
 Item 3. I get a sort of frightened feeling as if something awful is about to happen 1: 0.948 (0.782;1.149)
2: 0.801 (0.719;0.892)
3: 0.916 (0.820;1.023)
0.0007   0.6287 0.6293 0.6295 0.0008
 Item 5. Worrying thoughts go through my mind    X 0.6924 0.6930 0.6932 0.0008
 Item 7. I can sit at ease and feel relaxed    X 0.6008 0.6011 0.6018 0.0010
 Item 9. I get a sort of frightened feeling like ‘butterflies’ in the stomach    X 0.6718 0.6726 0.6730 0.0012
 Item 11. I feel restless as I have to be on the move 1:1.670 (1.315;2.122)
2: 1.385 (1.240;1.545)
3: 1.423 (1.289;1.571)
<.0001   0.4746 0.4785 0.4788 0.0042
 Item 13. I get sudden feelings of panic 1: 0.667 (0.462;0.963)
2: 0.712 (0.600;0.845)
3: 0.781 (0.703;0.868)
<.0001   0.6291 0.6307 0.6308 0.0017
HADS-D
 Item 2. I still enjoy the things I used to enjoy    X 0.6107 0.6112 0.6116 0.0009
 Item 4. I can laugh and see the funny side of things 1: 0.865 (0.587;1.274)
2: 0.917 (0.765;1.099)
3: 0.805 (0.719;0.902)
0.0025   0.5739 0.5747 0.5747 0.0008
Item 6. I feel cheerful 1: 1.079 (0.750;1.551)
2: 1.089 (0.937;1.266)
3: 1.071 (0.956;1.200)
0.5055   0.6381 0.6381 0.6385 0.0004
Item 8. I feel as if I am slowed down    X 0.5660 0.5676 0.5684 0.0024
Item 10. I have lost interest in my appearance 1: 0.813 (0.561;1.177)
2: 1.050 (0.905;1.218)
3: 0.956 (0.866;1.054)
0.3345   0.4235 0.4237 0.4239 0.0003
Item 12. I look forward with enjoyment to things    X 0.6136 0.6142 0.6143 0.0007
Item 14. I can enjoy a good book or radio or TV program 1: 2.132 (1.558;2.918)
2: 1.612 (1.361;1.909)
3: 1.431 (1.289;1.587)
<.0001   0.3805 0.3853 0.3855 0.0050
  1. a Partial proportional odds model with item response as dependent variable and gender and subscale as independent variable. Men are reference
  2. Step 1: Partial proportional odds model with item response as dependent variable including subscale
  3. Step 2: Partial proportional odds model with item response as dependent variable including subscale and gender
  4. Step 2: Partial proportional odds model with item response as dependent variable including subscale, gender and an interaction between the two
  5. b Indication of both uniform and non-uniform DIF