Glottal Function Index: Validity and Reliability of the Persian Language Version in Patients With Voice Disorders

Published:November 26, 2020DOI:



      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.


      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.


      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.


      The GFIp is a valid and reliable self-administered instrument for use in Persian-speaking patients with voice disorders.

      Key words

      To read this article in full you will need to make a payment

      Purchase one-time access:

      Academic & Personal: 24 hour online accessCorporate R&D Professionals: 24 hour online access
      One-time access price info
      • For academic or personal research use, select 'Academic and Personal'
      • For corporate R&D use, select 'Corporate R&D Professionals'


      Subscribe to Journal of Voice
      Already a print subscriber? Claim online access
      Already an online subscriber? Sign in
      Institutional Access: Sign in to ScienceDirect


        • Branski RC
        • Cukier-Blaj S
        • Pusic A
        • et al.
        Measuring quality of life in dysphonic patients: a systematic review of content development in patient-reported outcomes measures.
        J Voice. 2010; 24: 193-198
        • Roy N
        • Merrill RM
        • Gray SD
        • et al.
        Voice disorders in the general population: prevalence, risk factors, and occupational impact.
        Laryngoscope. 2005; 115: 1988-1995
        • Verdolini K
        • Ramig LO.
        Occupational risks for voice problems.
        Logoped Phoniatr Vocol. 2001; 26: 37-46
        • Rubin JS
        • Sataloff RT
        • Korovin GS
        Diagnosis and Treatment of Voice Disorders.
        Plural Publishing, 2014
        • Mathieson L.
        Greene and Mathieson's the Voice and its Disorders.
        John Wiley & Sons, 2013
        • Stemple JC
        • Roy N
        • Klaben BK
        Clinical Voice Pathology: Theory and Management.
        Plural Publishing, 2018
        • Bach KK
        • Belafsky PC
        • Wasylik K
        • et al.
        Validity and reliability of the glottal function index.
        Arch Otolaryngol Head Neck Surg. 2005; 131: 961-964
        • Dumberger LD
        • Overton L
        • Buckmire RA
        • et al.
        Trial vocal fold injection predicts thyroplasty outcomes in nonparalytic glottic incompetence.
        Ann Otol Rhinol Laryngol. 2017; 126: 279-283
        • Buckmire RA
        • Bryson PC
        • Patel MR
        Type I Gore-Tex laryngoplasty for glottic incompetence in mobile vocal folds.
        J Voice. 2011; 25: 288-292
        • Pribuišienė R
        • Baceviciene M
        • Uloza V
        • et al.
        Validation of the Lithuanian version of the glottal function index.
        J Voice. 2012; 26: e73-e78
        • Howell R
        • Webster H
        • Kissela E
        • et al.
        Dysphagia in Parkinson's disease improves with vocal augmentation.
        Dysphagia. 2019; 34: 862-868
        • Papa EC
        • Samson ES
        • Victoria FA
        Glottal function index and GRBAS scale of patients undergoing vocal cord medialization: a series of five patients.
        PhiliPPine J Otolaryngol Head Neck Surg. 2013; 28: 14-17
        • Overton L
        • Adams K
        • Shah RN
        • et al.
        Longitudinal voice outcomes after type I Gore-Tex thyroplasty for nonparalytic glottic incompetence.
        Ann Otol Rhinol Laryngol. 2017; 126: 14-19
        • Upton DC
        • Johnson M
        • Zelazny SK
        • et al.
        Prospective evaluation of office-based injection laryngoplasty with hyaluronic acid gel.
        Ann Otol Rhinol Laryngol. 2013; 122: 541-546
        • Koufman JA
        • Rees CJ
        • Halum SL
        • et al.
        Treatment of adductor-type spasmodic dysphonia by surgical myectomy: a preliminary report.
        Ann Otol Rhinol Laryngol. 2006; 115: 97-102
        • Young WG
        • Hoffman MR
        • Koszewski IJ
        • et al.
        Voice outcomes following a single office-based steroid injection for vocal fold scar.
        Otolaryngol Head Neck Surg. 2016; 155: 820-828
        • Cohen JT
        • Oestreicher-Kedem Y
        • Fliss DM
        • et al.
        Glottal function index: a predictor of glottal disorders in children.
        Ann Otol Rhinol Laryngol. 2007; 116: 81-84
        • Beaton DE
        • Bombardier C
        • Guillemin F
        • et al.
        Guidelines for the process of cross-cultural adaptation of self-report measures.
        Spine. 2000; 25: 3186-3191
        • Terwee CB
        • Bot SD
        • de Boer MR
        • et al.
        Quality criteria were proposed for measurement properties of health status questionnaires.
        J Clin Epidemiol. 2007; 60: 34-42
        • Moradi N
        • Pourshahbaz A
        • Soltani M
        • et al.
        Cross-cultural equivalence and evaluation of psychometric properties of voice handicap index into Persian.
        J Voice. 2013; 27 (e215-258. e222): 258
        • Ansari NN
        • Feise RJ
        • Naghdi S
        • et al.
        The functional rating index: reliability and validity of the Persian language version in patients with low back pain.
        Spine. 2011; 36: E1573-E1577
        • Nakhostin Ansari N
        • Naghdi S
        • Habibzadeh F
        • et al.
        Persian translation and validation of the back pain functional scale.
        Physiother Theory Pract. 2018; 34: 223-230
        • Pribuisiene R
        • Pasvenskaite A
        • Pribuisis K
        • et al.
        Dysphonia screening in vocally trained and untrained children.
        Int J Pediatr Otorhinolaryngol. 2020; 129109776
        • Ulozaite-Staniene N
        • Petrauskas T
        • Šaferis V
        • et al.
        Exploring the feasibility of the combination of acoustic voice quality index and glottal function index for voice pathology screening.
        Eur Arch Otorhinolaryngol. 2019; 276: 1737-1745
        • Pribuisiene R
        • Pribuisis K
        • Liutkevicius V
        • et al.
        Glottal function index questionnaire for screening of pediatric dysphonia.
        Int J Pediatr Otorhinolaryngol. 2019; 123: 97-101
        • Ruel B
        • Thibeault S.
        Is there a relationship between vocal effort and VHI?.
        J Voice. 2020; 34 (809. e811–809. e818)
        • Acquadro C
        • Conway K
        • Hareendran A
        • et al.
        Literature review of methods to translate health‐related quality of life questionnaires for use in multinational clinical trials.
        Value Health. 2008; 11: 509-521
        • Jacobson BH.
        The voice handicap index (VHI): development and validation.
        Am J Speech-Lang Pathol. 1997; 6: 66-70
        • Gliklich RE
        • Glovsky RM
        • Montgomery WW
        Validation of a voice outcome survey for unilateral vocal cord paralysis.
        Otolaryngol Head Neck Surg. 1999; 120: 153-158
        • Hogikyan ND
        • Sethuraman G.
        Validation of an instrument to measure voice-related quality of life (V-RQOL).
        J Voice. 1999; 13: 557-569
        • Ma EP
        • Yiu EM
        Voice activity and participation profile.
        J Speech Lang Hear Res. 2001; 44: 511-524
        • Deary IJ
        • Wilson JA
        • Carding PN
        • et al.
        VoiSS: a patient-derived voice symptom scale.
        J Psychosom Res. 2003; 54: 483-489
        • Ansari NN
        • Naghdi S
        • Eskandari Z
        • et al.
        Reliability and validity of the Persian adaptation of the core outcome measure index in patients with chronic low back pain.
        J Orthop Sci. 2016; 21: 723-726
        • Ansari NN
        • Kashi M
        • Naghdi S
        The spinal cord injury spasticity evaluation tool: a Persian adaptation and validation study.
        J Spinal Cord Med. 2017; 40: 380-388
        • Bruton A
        • Conway JH
        • Holgate ST
        Reliability: what is it, and how is it measured.
        Physiotherapy. 2000; 86: 94-99