Persian translation and validation of the Back Pain Functional Scale
Noureddin Nakhostin Ansari1,2, Soofia Naghdi1,2, Fatemeh Habibzadeh1
1a Department of Physiotherapy, School of Rehabilitation , Tehran University of Medical Sciences , Tehran , Iran.
Background:
Patient-reported questionnaires provide important tools that can be utilized for the assessment of treatment efficacy in clinic and research. This study aimed to translate, cross-culturally adapt, and validate the Back Pain Functional Scale into Persian (BPFSp).
Methods:
In this cross-sectional and prospective cohort of adult patients with low back pain (LBP), the translation and adaptation was performed according to standardized guidelines and pretested (n = 30). Psychometric testing was conducted with 100 patients with LBP and 50 healthy subjects. Fifty patients with LBP recompleted the BPFSp at least 7 days later for test-retest reliability.
Results:
The Persian adapted version of the BPFS was produced and validated. No floor and ceiling effects were revealed. The Cronbach'α coefficient for internal consistency was 0.895. The test-retest reliability was excellent (ICCagreement = 0.88, CI 95%: 0.80-0.93). The standard error of measurement and smallest detectable change were 9.9% and 27.5%, respectively. Construct convergent validity was demonstrated with the Persian Functional Rating Index (r = -0.77). Criterion validity was established with the Numerical Pain Rating Scale (r = -0.67). Total BPFSp scores discriminated between patients with LBP and healthy subjects. Factor structure showed two latent factors explaining a total variance of 60.1%.
Conclusion:
The BPFSp presented excellent reliability and validity for assessing the functional status in Persian speaking patients with LBP.
