Creating a common scale for the conversion of qDASH and PRWHE scores

Area of Science:

• Orthopedics
• Hand Surgery
• Health Outcomes Research
• Psychometrics

Background:

• The Quick Disabilities of the Arm, Shoulder and Hand Questionnaire (DASH) and Patient Rated Wrist and Hand Evaluation (PRWHE) are widely used patient-reported outcome measures (PROMs) in hand surgery.
• Assessing the structural validity and comparability of these instruments is crucial for robust clinical research and practice.
• Current limitations exist in directly comparing scores between the DASH and PRWHE.

Purpose of the Study:

• To evaluate the structural validity of the DASH and PRWHE using item response theory.
• To develop a common, unified scale for mapping scores from both the DASH and PRWHE.
• To facilitate direct comparison of patient outcomes between these two frequently used instruments.

Main Methods:

• Item response theory (IRT) and factor analysis were employed to assess the underlying structure of the DASH and PRWHE.
• Common scales were developed for the identified health constructs: 'Pain' and 'Motor Function'.
• Frequency density plots and Bland-Altman analysis were used to evaluate the comparability of scores between the two measures.

Main Results:

• Factor analysis confirmed that both the DASH and PRWHE measure the same two primary health constructs: 'Pain' and 'Motor Function'.
• Two distinct common scales were successfully developed, one for 'Pain' and one for 'Motor Function'.
• Statistical analyses indicated that the developed scales allow for reliable comparison of scores between the DASH and PRWHE.

Conclusions:

• The DASH and PRWHE demonstrate shared structural validity concerning 'Pain' and 'Motor Function'.
• The newly developed common scales and accompanying lookup table provide a valuable tool for comparing outcomes measured by these instruments.
• This facilitates more consistent and comparable reporting of results in hand surgery research and clinical practice.