Reference values for the PROMIS^® physical function item bank version 2.0 in the general population: a multinational...

We aimed to obtain general population-based Korean reference values for the Patient-Reported Outcomes Measurement Information System (PROMIS) Physical Function (PF) item bank v2.0 and to compare them with US and Netherlands reference values.

In April 2021, we surveyed Korean representative participants (N = 2,124) using the PROMIS PF item bank. We compared the mean T-scores of the Netherlands (N = 1,310) and US populations (N = 1,646) using ANOVA by age group, sex, presence of comorbidities, and general health. We also performed Differential item functioning (DIF) analyses between the US and Korea populations.

In Korean, the PF T-score was 55.3 (SD = 9.1), ranging from 28.7 to 77.6. This score was higher compared to the mean score of 50.0 in the US and 49.8 in the Netherlands general populations. Differences in PF were generally observed in all age and sex groups. In the PF item bank, 57 of 131 items were flagged for uniform or nonuniform DIF. Among the general population in Korea, older adults, women, those with lower levels of education, and those with comorbidities had lower levels of PF compared to their counterparts in the general Korean population.

Considering the cultural differences between Western and Asian countries, we recommend establishing country-specific reference values on a global scale.