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Table 5 Uncertainty Domain (5 items) - Overview of final SF-HDQ item level and domain model fit statistics

From: Developing a short-form version of the HIV Disability Questionnaire (SF-HDQ) for use in clinical practice: a Rasch analysis

Item #

Final SF-HDQ items

Item level statistics

Uncertainty domain

Location

SE

Residual

ChiSq χ2

p value

35

Worry about future health living with HIV

− 0.114

0.041

− 1.295

25.455

0.002a

36

Worry about lab test results such as my CD4 count and viral load

0.701

0.041

0.084

13.146

0.156

39

Worry about the side effects of HIV treatments

0.069

0.038

0.793

5.110

0.825

40

Worry about income or financial security living with HIV

− 0.608

0.035

0.900

6.796

0.658

41

Worry what might happen to my family and friends if have an episode of illness

− 0.048

0.037

0.618

7.220

0.614

Final model: uncertainty domain—5 items (raw score range: 0–20)

 Mean

− 0.366

 Standard deviation

1.190

 Sample size

930

 Chi-square statistic (df) p value

58.7265 (df: 45) p = 0.0965b

 Cronbach’s alpha

0.82314

 Person Separation Index

0.78006

 Unidimensionality t-test (% significant)

1.72%

Differential Item Functioning (DIF) 

None

  1. aSignificant residual (p < 0.004; Bonferroni: 0.05/14) but fit residual F value <  ± 2.5
  2. bChi-square statistic not significant (ideal outcome). HDQ43—removed as this item considered to be captured by HDQ35 worry about future health