Many questionnaires are available that measure the same health-related construct such as physical functioning. In this project we developed a crosswalk for converting scores on two of the most frequently used measures of physical functioning. The crosswalk was developed using a novel approach of item response theory (IRT) based methods in Dutch patient with rheumatoid arthritis. More recently, the generalizability and accuracy of the crosswalk was demonstrated in patients with different rheumatic diseases in the United States as well. The methodology and crosswalk developed in this study provide an important step in achieving better interpretation and comparability of results across different studies and populations.
- Martijn Oude-Voshaar