Summary
Objective
To translate and cross-culturally adapt the Glottal Function Index into the Persian
language (GFIp) and validate it in patients with voice disorders.
Study design
A cross-sectional and prospective validation design was adopted.
Method
The GFI was translated and culturally adapted into Persian language according to the
methodology of standard forward-backward translations to obtain semantic, idiomatic,
and conceptual equivalence. One hundred patients with voice disorders (53 men; mean
age: 41.4 ± 13.6 years) and 40 healthy volunteers (21 women; mean age: 36.7 ± 10.0
years) completed the GFIp. Patients with voice disorders also completed the Persian
Voice Handicap Index (VHIp) to assess the construct validity.
Results
There were no floor and ceiling effects. Evidence for construct validity was found
with a significant very good correlation between the GFIp and the VHIp total scores
(r = 0.70; P < 0.001). Differences of GFIp scores between the patients and healthy participants
were statistically significant (P < 0.001) confirming discriminant validity. The internal consistency reliability was
acceptable for GFIp (Cronbach's α = 0.74). Absolute reliability measures of Standard
Error of Measurement and the Smallest Detectable Change for GFIp were 2.5 (confidence
interval 95% = ±4.9) and 6.93, respectively. Factor analysis revealed the GFIp as
a single factor instrument.
Conclusion
The GFIp is a valid and reliable self-administered instrument for use in Persian-speaking
patients with voice disorders.
Key words
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Article info
Publication history
Published online: November 26, 2020
Accepted:
October 19,
2020
Footnotes
Funding/Support: This study was supported by School of Rehabilitation, Arak University of Medical Sciences as a part of the research project (Grant Number: 2966).
Identification
Copyright
© 2020 The Voice Foundation. Published by Elsevier Inc. All rights reserved.
