Country-specific reference values for PROMIS(R) pain, physical function and participation measures compared to US reference values

Introduction Patient-Reported Outcomes Measurement Information System (PROMIS(R)) is commonly used across medical conditions. To facilitate interpretation of scores across countries, we calculated Dutch reference values for PROMIS Physical Function (PROMIS-PF), Pain Interference (PROMIS-PI), Pain Behavior (PROMIS-PB), Ability to Participate in Social Roles and Activities (PROMIS-APSRA), and Satisfaction with Social Roles and Activities (PROMIS-SSRA), as compared to US reference values. Patients and methods A panel completed full PROMIS-PF (n=1310), PROMIS-PI and PROMIS-PB (n=1052), and PROMIS-APSRA and PROMIS-SSRA (n=1002) item banks and reported their level of health per domain (no, mild, moderate, severe limitations). T-scores were calculated by sample and subgroups (age, gender, self-reported level of domain). Distribution-based and anchor-based thresholds for mild, moderate, and severe scores were determined. Results Mean T-scores were close to the US mean of 50 for PROMIS-PF (49.8) and PROMIS-APSRA (50.6), lower for PROMIS-SSRA (47.5) and higher for PROMIS-PI (54.9) and PROMIS-PB (52.0). Distribution-based thresholds for mild, moderate, and severe scores were comparable to US recommended cut-off values (except for PROMIS-PI) but participants reported limitations 'earlier' than suggested thresholds. Conclusion Dutch reference values were close to US reference values for some PROMIS domains but not all. We recommend country-specific reference values to facilitate worldwide PROMIS use. KEY MESSAGES PROMIS offers universally applicable IRT-based efficient and patient-friendly measures to assess commonly relevant patient-reported outcomes across medical conditions. To support the use of PROMIS in daily clinical practice and research across the world, country-specific general population reference values should be obtained. More research is necessary to obtain reliable and valid cut-off values for what constitutes mild, moderate and severe scores from the patients' perspective.