Table 3. PROMIS anxiety and depression T-scoresa based on different sets of item parameters for different versions of the instruments.
| Version | Mean population T-score (SD) original approachb | Mean population T-score (SD) hybrid approachc | Mean absolute T-score difference (SD), [range] |
|---|---|---|---|
| Anxiety | |||
| Full item bank | 49.9 (10.1) | 49.5 (10.3) | 0.40 (0.29) [0.00–1.67] |
| Short form 7a | 50.3 (9.2) | 49.8 (9.6) | 0.59 (0.48) [0.00–1.88] |
| Depression | |||
| Full item bank | 49.6 (10.0) | 49.7 (9.9) | 0.15 (0.09) [0.00–0.73] |
| Short form 4a | 50.9 (8.5) | 49.9 (8.7) | 1.02 (0.52) [0.00–2.57] |
| Short form 6a | 49.7 (9.3) | 49.8 (9.0) | 0.52 (0.29) [0.00–1.24] |
| Short form 8a | 50.3 (9.2) | 50.4 (8.9) | 0.42 (0.25) [0.01–1.10] |
| Short form 8b | 50.2 (9.3) | 50.2 (9.1) | 0.38 (0.22) [0.00–1.15] |
SD: standard deviation
a T-scores, higher scores represent more anxiety/depression
b All items have the US item parameters
c Non-DIF items have the US item parameters, DIF items have the Dutch item parameters rescaled to the US metric