Table 3.
PROMIS Global Health items descriptives, scalability, graded response model fit, range of item discrimination and difficulties, internal consistency, measurement invariance and cross-cultural validity in the total sample of the Dutch general population (N = 4370)
| Items description | Descriptives | Mokken scalability | GRM model fit | Range of item discrimination and difficulties* | Internal consistency | Measurement invariance | Cross cultural validity | |||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Mean (SD) | Range (Min–Max) | Skewness (SE) | Kurtosis (SE) | Hi (SE) | S-X2 | p | α | β1 | β2 | β3 | β4 | IIT | αIID | Sex | Age | Region | Educ. level | Ethnicity | ||
| Global Mental Health | ||||||||||||||||||||
| Global02: quality of life |
3.0 (0.9) |
1–5 |
0.08 (0.04) |
− 0.17 (0.07) |
0.633 (0.009) |
94.550 | < 0.001 | 3.507 | − 1.935 | − 0.603 | 0.710 | 1.893 | 0.72 | 0.76 | 0.0025 | 0.0065 | 0.0005 | 0.0014 | 0.0001 | 0.0041 |
| Global04: mental health, including mood and ability to think |
3.1 (1.0) |
1–5 | 0.01 (0.04) | − 0.32 (0.07) |
0.654 (0.009) |
160.820 | < 0.001 | 2.757 | − 2.047 | − 0.783 | 0.529 | 1.648 | 0.73 | 0.75 | 0.0007 | 0.0031 | 0.0001 | 0.0006 | 0.0011 | 0.0028 |
| Global05: satisfaction with social activities and relationships |
3.0 (0.9) |
1–5 | 0.03 (0.04) | − 0.15 (0.07) |
0.603 (0.010) |
87.731 | < 0.001 | 2.849 | − 1.855 | − 0.644 | 0.739 | 1.916 | 0.68 | 0.78 | 0.0017 | 0.0031 | 0.0003 | 0.0012 | 0.0018 | 0.0032 |
| Global10: bothered by emotional problems |
3.7 (1.0) |
1–5 | − 0.31 (0.04) | − 0.64 (0.07) |
0.518 (0.012) |
323.387 | < 0.001 | 1.321 | − 3.717 | − 1.779 | − 0.220 | 1.181 | 0.52 | 0.85 | 0.0070 | 0.0165 | 0.0017 | 0.0034 | 0.0020 | 0.0136 |
| Global physical health | ||||||||||||||||||||
| Global03: physical health |
2.7 (0.9) |
1–5 |
0.24 (0.04) |
− 0.23 (0.07) |
0.565 (0.010) |
145.562 | < 0.001 | 2.266 | − 1.792 | − 0.239 | 1.094 | 2.248 | 0.62 | 0.71 | 0.0010 | 0.0022 | 0.0019 | 0.0021 | 0.0041 | 0.0046 |
| Global06: carry out every day physical activities |
4.1 (1.2) |
1–5 | − 0.91 (0.04) | − 0.32 (0.07) |
0.525 (0.013) |
184.359 | < 0.001 | 1.943 | − 2.668 | − 1.619 | − 0.705 | − 0.055 | 0.55 | 0.74 | 0.0018 | 0.0013 | 0.0005 | 0.0030 | 0.0003 | 0.0006 |
| Global07: pain on average |
3.1 (2.7) |
1–5 | 0.41 (0.04) | − 1.16 (0.07) |
0.547 (0.010) |
82.367 | < 0.001 | 2.063 | − 3.641 | − 1.306 | − 0.279 | 0.916 | 0.62 | 0.71 | 0.0013 | 0.0047 | 0.0002 | 0.0013 | 0.0011 | 0.0048 |
| Global08: fatigue on average |
3.4 (1.0) |
1–5 | − 0.16 (0.04) | − 0.50 (0.07) |
0.513 (0.011) |
64.189 | < 0.001 | 1.705 | − 2.844 | − 1.291 | 0.144 | 1.548 | 0.56 | 0.74 | 0.0029 | 0.0458 | 0.0018 | 0.0049 | 0.0034 | 0.0002 |
| Items not contributing to the subscale scores | ||||||||||||||||||||
| Global01: general health |
2.8 (0.9) |
1–5 |
0.20 (0.04) |
− 0.16 (0.07) | – | – | – | – | – | – | – | – | – | – | – | – | – | – | – | – |
| Global09: usual social activities and roles |
3.0 (0.9) |
1–5 |
0.07 (0.04) |
− 0.12 (0.07) | – | – | – | – | – | – | – | – | – | – | – | – | – | – | – | – |
| Recommended values | N/A | N/A | N/A | N/A | > 0.30 | N/A | ≥ 0.001 | > 1.0 | N/A | N/A | N/A | N/A | ≥ 0.40 | < α | < 0.02 | < 0.02 | < 0.02 | < 0.02 | < 0.02 | < 0.02 |
α, Cronbach’s alpha; αIID, α if item deleted GRM, Graded Response Model; Hi, scalability coefficient for item; IIC, itam-to-total correlation; N/A, not applicable; p, p-value; S-X2, item fit statistics under the Graded Response Model; SD, standard deviation; SE, standard error
Statistics values beyond the recommended cut-offs presented in bold
For interpretation of the indexes, refer to Table 1
Global08 and Global10 have been recoded according the instruction in the PROMIS-GH Scoring Manual
Possible response range for each item varies from 1 to 5 points
Cross-cultural validity was studied using data from the US PROMIS Wave 1 sample, obtained from the Health Measures Dataverse [12, 18]
* Item parameters were estimated using the Dutch dataset in this paper; the official PROMIS item parameters used in CAT are available from help@healthmeasures.net