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Table 3 Discriminative validity of the Insomnia Severity Index Danish version (ISI-DK)

From: Preliminary validation of the insomnia severity index in Danish outpatients with a medical condition

Hypotheses Mean ISI-DK score (SD)
Gender: Female responders have significantly higher ISI-DK mean scores compared to male responders
 Male, n = 91 9.36 (6.03)
 Female, n = 158 10.74 (6.02)
  Effect size (Cohen’s d) 0.23
  p-value 0.083
  Confirmed hypothesis No
Age: Responders ≥ 70 years old have significantly lower ISI-DK mean scores compared to younger responders
 ≥ 70, n = 60 8.85 (6.55)
 ≤ 69, n = 188 10.65 (5.83)
  Effect size (Cohen’s d) 0.40
  p-value 0.044
  Confirmed hypothesis Yes
EQ VAS: Responders with EQ VAS score < 83.7 have significantly higher ISI-DK mean scores compared to responders with higher EQ VAS scores
 VAS score ≤ 83.6, n = 189 11.21 (6.00)
 VAS score ≥ 83.7, n = 60 7.18 (5.13)
  Effect size (Cohen’s d) 0.69
  p-value < 0.001
  Confirmed hypothesis Yes
EQ-5D anxiety/depression: Responders with any EQ-5D anxiety/depression problem have significantly higher ISI-DK mean scores compared to responders with no problem
 Anxiety/depression no problems, n = 132 8.23 (5.66)
 Anxiety/depression problems, n = 117 12.50 (5.68)
  Effect size (Cohen’s d) 0.75
  p-value < 0.001
  Confirmed hypothesis Yes
EQ-5D pain/discomfort: Responders with any EQ-5D pain/discomfort problem have significantly higher ISI-DK mean scores compared to responders with no problem
 Pain/discomfort no problems, n = 64 7.44 (5.28)
 Pain/discomfort problems, n = 185 11.21 (6.01)
  Effect size (Cohen’s d) 0.65
  p-value < 0.001
  Confirmed hypothesis Yes
  1. Cut-off for effect size: 0.2 (small), 0.5 (medium) and 0.8 (large)