Responsiveness and minimal clinically important changes of the Persian version of the back pain functional scale and spine functional index in patients with non-specific chronic low back pain.

INTRODUCTION

Chronic low back pain is a common condition that often results in long-term disability and reduced quality of life.

PURPOSE: To assess the responsiveness and determine the Minimal Clinically Important Change (MCIC) of the Persian version of the Back Pain Functional Scale (BPFS) and Spine Functional Index (SFI) in patients with nonspecific chronic low back pain (LBP) following physiotherapy intervention.

METHODS

Patients with nonspecific chronic LBP, recruited from outpatient clinics, completed the BPFS, SFI, Roland-Morris Disability Questionnaire (RMDQ), and Functional Rating Index (FRI) at pre-treatment. At post-treatment, these four questionnaires, along with the Global Rating of Change Scale (GRS), were administered. Responsiveness was evaluated using a criterion approach with the area under the receiver operating characteristic curve (AUC) and a construct approach by testing eight a priori hypotheses. The MCIC was determined as the optimal cutoff point on the ROC curve using GRS as an external anchor.

RESULTS

A total of 100 patients with nonspecific chronic LBP participated in the study. The AUC was acceptable for both the BPFS (0.83) and the SFI (0.75). All predefined hypotheses were supported by both the BPFS and the SFI. The MCIC values were 9.5 for the BPFS and 13.5 for the SFI.

CONCLUSION

The Persian versions of the BPFS and SFI are responsive and clinically useful tools for evaluating functional changes in patients with nonspecific chronic LBP following physiotherapy. These tools can be effectively utilized in both clinical and research settings to monitor treatment outcomes.