Content validity and responsiveness of the Patient-Specific Functional Scale in patients with Dupuytren's disease.

INTRODUCTION

Patient-reported outcome measures have become the standard tool for reflecting the patient's perspective on their treatment outcome for a wide variety of hand conditions. The Patient-Specific Functional Scale (PSFS), is an individualized questionnaire that enables patients to specify those activities with which they have difficulty in daily life.

PURPOSE OF THE STUDY

This study aims to determine the content validity and responsiveness of the PSFS compared with the Michigan Hand Questionnaire (MHQ) in patients with Dupuytren's disease.

STUDY DESIGN

Multicentre inception cohort.

METHODS

Patients with Dupuytren's disease being treated with percutaneous needle aponeurotomy, limited fasciectomy, or skin graft were selected from a database with routine outcome measurements in usual care. To assess content validity of the PSFS, the activities specified by patients were classified into the International Classification of Function core set for hand conditions. The standardized response mean is calculated for the pre- and post-change scores of the PSFS to evaluate responsiveness.

RESULTS

Three hundred and eight patients were analyzed before and three months after treatment. Content validity of the PSFS was appropriate because 95% of all items could be classified into the International Classification of Function activities and participation domain. The standardized response mean of the PSFS was 1.0 (95% confidence interval, 0.86-1.2), which was substantially larger than the standardized response mean of the MHQ score 0.58 (95% confidence interval, 0.42-0.74).

DISCUSSION

The PSFS is a content-valid questionnaire which may be more responsive to change than a fixed-item instrument such as the MHQ in patients with Dupuytren's disease.

CONCLUSIONS

The PSFS is a valuable tool to set therapy goals and evaluate the progress over time in patients with Dupuytren's disease.