Psychometric properties and reference values of the Patient-Reported Outcomes Measurement Information System (PROMIS) sleep item banks in the Dutch general population

Psychometric properties of the v1.0 Patient-Reported Outcomes Measurement Information System (PROMIS (R)) sleep disturbance (27 items) and sleep-related impairment (SRI; 16 items) item banks, short forms derived from the item bank, and simulated computerised adaptive test (CAT), were assessed in a representative sample of 1,006 adults from the Dutch general population. For sleep disturbance all items fitted the item response theory model. Four items showed differential item functioning (i.e., lack of measurement invariance) for age and two for language but the impact on scores (expressed as T-scores) was small. Reliable scores (r > 0.90) were found for 92.2%-96.3% of respondents with the full bank, short forms with six and eight items, and CAT, but for only 25.6% with the four-item short form. For SRI two items did not fit the item response theory model. Four items showed differential item functioning for language but the impact on T-scores was small. Reliable scores were found for 82.1% with the full bank, for 47.8%-69.5% with short forms and CAT. T-scores of 49.7 and 49.3 represent the average score of the Dutch general population for sleep disturbance and SRI, respectively. In conclusion, sufficient structural validity, reliability, and cross-cultural validity was found for the full banks but short forms of four items are not reliable enough for clinical practice. For SRI we recommend the full item bank if this is the primary outcome.