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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 scaleNagelkerke’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’  X0.67120.67140.67170.0005
 Item 3. I get a sort of frightened feeling as if something awful is about to happen1: 0.948 (0.782;1.149)
2: 0.801 (0.719;0.892)
3: 0.916 (0.820;1.023)
0.0007 0.62870.62930.62950.0008
 Item 5. Worrying thoughts go through my mind  X0.69240.69300.69320.0008
 Item 7. I can sit at ease and feel relaxed  X0.60080.60110.60180.0010
 Item 9. I get a sort of frightened feeling like ‘butterflies’ in the stomach  X0.67180.67260.67300.0012
 Item 11. I feel restless as I have to be on the move1:1.670 (1.315;2.122)
2: 1.385 (1.240;1.545)
3: 1.423 (1.289;1.571)
<.0001 0.47460.47850.47880.0042
 Item 13. I get sudden feelings of panic1: 0.667 (0.462;0.963)
2: 0.712 (0.600;0.845)
3: 0.781 (0.703;0.868)
<.0001 0.62910.63070.63080.0017
HADS-D
 Item 2. I still enjoy the things I used to enjoy  X0.61070.61120.61160.0009
 Item 4. I can laugh and see the funny side of things1: 0.865 (0.587;1.274)
2: 0.917 (0.765;1.099)
3: 0.805 (0.719;0.902)
0.0025 0.57390.57470.57470.0008
Item 6. I feel cheerful1: 1.079 (0.750;1.551)
2: 1.089 (0.937;1.266)
3: 1.071 (0.956;1.200)
0.5055 0.63810.63810.63850.0004
Item 8. I feel as if I am slowed down  X0.56600.56760.56840.0024
Item 10. I have lost interest in my appearance1: 0.813 (0.561;1.177)
2: 1.050 (0.905;1.218)
3: 0.956 (0.866;1.054)
0.3345 0.42350.42370.42390.0003
Item 12. I look forward with enjoyment to things  X0.61360.61420.61430.0007
Item 14. I can enjoy a good book or radio or TV program1: 2.132 (1.558;2.918)
2: 1.612 (1.361;1.909)
3: 1.431 (1.289;1.587)
<.0001 0.38050.38530.38550.0050
  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