Table 2 Model-fit results of confirmatory factor analysis (CFA) of extended item bank (51 items), final item bank (28 items) and short-form 8b (8 items) of the PROMIS Depression Item Bank using WLSMV^a,b

Unidimensional model with 51 items

5729.6

1224

<.001

0.070 [0.068; 0.072]

0.953

0.951

Unidimensional model with 28 items

1473.27

350

<.001

0.065 [0.062; 0.069]

0.983

0.982

Unidimensional model with 8 items

177.71

20

<.001

0.101 [0.088; 0.115]

0.995

0.992