The Patient Specific Functional Scale - Brazil as an instrument for the functional assessment of patients with chronic non-specific low back pain: Construct validity (hypothesis testing and structural validity) and test-retest reliability.

The objective was to assess the validity and reliability of the Patient-Specific Functional Scale-Brazil (PSFS-B) in patients with non-specific chronic low back pain. A methodological study was conducted, and 101 volunteers with chronic non-specific low back pain were interviewed and asked to complete the PSFS-B questionnaire and the Oswestry Disability Index-Brazil 2.0 reference questionnaire.