Quality of Life Research

, Volume 24, Issue 3, pp 769–780 | Cite as

Cross-cultural validity of the thyroid-specific quality-of-life patient-reported outcome measure, ThyPRO

  • Torquil WattEmail author
  • Giuseppe Barbesino
  • Jakob Bue Bjorner
  • Steen Joop Bonnema
  • Branka Bukvic
  • Russell Drummond
  • Mogens Groenvold
  • Laszlo Hegedüs
  • Valeska Kantzer
  • Kathryn E. Lasch
  • Claudio Marcocci
  • Anjali Mishra
  • Romana Netea-Maier
  • Merel Ekker
  • Ivan Paunovic
  • Terence J. Quinn
  • Åse Krogh Rasmussen
  • Audrey Russell
  • Mayilvaganan Sabaretnam
  • Johannes Smit
  • Ove Törring
  • Vladan Zivaljevic
  • Ulla Feldt-Rasmussen


Background and purpose

Thyroid diseases are common and often affect quality of life (QoL). No cross-culturally validated patient-reported outcome measuring thyroid-related QoL is available. The purpose of the present study was to test the cross-cultural validity of the newly developed thyroid-related patient-reported outcome ThyPRO, using tests for differential item functioning (DIF) according to language version.


The ThyPRO consists of 85 items summarized in 13 multi-item scales and one single item. Scales cover physical and mental symptoms, well-being and function as well as social and daily function and cosmetic concerns. Translation applied standard forward–backward methodology with subsequent cognitive interviews and reviews. Responses (N = 1,810) to the ThyPRO were collected in seven countries: UK (n = 166), The Netherlands (n = 147), Serbia (n = 150), Italy (n = 110), India (n = 148), Denmark (n = 902) and Sweden (n = 187). Translated versions were compared pairwise to the English version by examining uniform and nonuniform DIF, i.e., whether patients from different countries respond differently to a particular item, although they have identical level of the concept measured by the item. Analyses were controlled for thyroid diagnosis. DIF was investigated by ordinal logistic regression, testing for both statistical significance and magnitude (ΔR 2 > 0.02). Scale level was estimated by the sum score, after purification.


For twelve of the 84 tested items, DIF was identified in more than one language. Eight of these were small, but four were indicative of possible low translatability. Twenty-one instances of DIF in single languages were identified, indicating potential problems with the particular translation. However, only seven were of a magnitude which could affect scale scores, most of which could be explained by sample differences not controlled for.


The ThyPRO has good cross-cultural validity with only minor cross-cultural invariance and is recommended for use in international multicenter studies.


Thyroid diseases Quality of life Patient-reported outcome measure Cross-cultural validity Differential item functioning 



This study has been supported by grants from the Danish Agency for Science, Technology and Innovation: Council for Strategic Research and Council for Independent Research and by Genzyme Corporation by an unrestricted research grant. Special thanks to Sabrina Sereni, Supriya Mathur, Kajsa Bergman, Gitte Karina Geil, Kim Æbelø, Selma Flora Watt and Laura Siim Magnussen for assistance with data entry and logistics.

Conflict of interest

None of the authors have any financial conflict of interest to declare. The ThyPRO was developed by TW, UFR, ÅKR, JBB, MG, SB and LH.

Supplementary material

11136_2014_798_MOESM1_ESM.pdf (104 kb)
Supplementary material 1 (PDF 104 kb)
11136_2014_798_MOESM2_ESM.pdf (16 kb)
Supplementary material 2 (PDF 16 kb)


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Copyright information

© Springer International Publishing Switzerland 2014

Authors and Affiliations

  • Torquil Watt
    • 1
    Email author
  • Giuseppe Barbesino
    • 2
  • Jakob Bue Bjorner
    • 3
  • Steen Joop Bonnema
    • 4
  • Branka Bukvic
    • 5
  • Russell Drummond
    • 6
  • Mogens Groenvold
    • 7
  • Laszlo Hegedüs
    • 4
  • Valeska Kantzer
    • 8
  • Kathryn E. Lasch
    • 9
  • Claudio Marcocci
    • 10
  • Anjali Mishra
    • 11
  • Romana Netea-Maier
    • 12
  • Merel Ekker
    • 12
  • Ivan Paunovic
    • 5
  • Terence J. Quinn
    • 6
  • Åse Krogh Rasmussen
    • 1
  • Audrey Russell
    • 13
  • Mayilvaganan Sabaretnam
    • 14
  • Johannes Smit
    • 12
  • Ove Törring
    • 15
  • Vladan Zivaljevic
    • 5
  • Ulla Feldt-Rasmussen
    • 1
  1. 1.Department of EndocrinologyCopenhagen University Hospital RigshospitaletCopenhagen ØDenmark
  2. 2.Massachusetts General HospitalBostonUSA
  3. 3.QualityMetricLincolnUSA
  4. 4.Department of Endocrinology and MetabolismOdense University HospitalOdenseDenmark
  5. 5.Clinical Centre of SerbiaBelgradeSerbia
  6. 6.Institute of Cardiovascular and Medical SciencesUniversity of GlasgowGlasgowScotland, UK
  7. 7.Research Unit, Department of Palliative Medicine, Bispebjerg Hospital and Department of Health Service Research, University of CopenhagenCopenhagenDenmark
  8. 8.Health Research Associates Inc.Mountlake TerraceUSA
  9. 9.Pharmerit InternationalBethesdaUSA
  10. 10.University Department of Clinical and Experimental Medicine, University of Pisa, and Endocrine Unit 2, University Hospital of PisaPisaItaly
  11. 11.Sanjay Gandhi Postgraduate Institute of Medical SciencesLucknowIndia
  12. 12.Department of Internal MedicineRadboud University Medical Center NijmegenNijmegenNetherlands
  13. 13.University College CorkCorkIreland
  14. 14.Christian Medical CollegeVelloreIndia
  15. 15.Institution for Clinical Science and EducationKarolinska Institutet SödersjukhusetStockholmSweden

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