Cross-cultural validity of the thyroid-specific quality-of-life patient-reported outcome measure, ThyPRO
- 554 Downloads
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.
KeywordsThyroid 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.
- 4.Abraham-Nordling, M., Torring, O., Hamberger, B., Lundell, G., Tallstedt, L., Calissendorff, J., et al. (2005). Graves’ disease: A long-term quality-of-life follow up of patients randomized to treatment with antithyroid drugs, radioiodine, or surgery. Thyroid, 15(11), 1279–1286.CrossRefPubMedGoogle Scholar
- 12.Wild, D., Grove, A., Martin, M., Eremenco, S., McElroy, S., Verjee-Lorenz, A., et al. (2005). Principles of good practice for the translation and cultural adaptation process for patient-reported outcomes (PRO) measures: report of the ISPOR task force for translation and cultural adaptation. Value Health, 8(2), 94–104.CrossRefPubMedGoogle Scholar
- 13.Reeve, B. B., Wyrwich, K. W., Wu, A. W., Velikova, G., Terwee, C. B., Snyder, C. F., et al. (2013). ISOQOL recommends minimum standards for patient-reported outcome measures used in patient-centered outcomes and comparative effectiveness research. Quality of Life Research, 22(8), 1889–1905.CrossRefPubMedGoogle Scholar
- 14.US Food and Drug administration. (2009). Guidance for Industry. Patient-reported outcome measures: Use in medical product development to support labeling claims. Health and Quality of Life Outcomes 4(79). doi: 10.1186/1477-7525-4-79.
- 16.Marquis, P., Keininger, D. L., Acquadro, C., et al. (2005). Translating and evaluating questionnaires: Cultural issues for international research. In P. Fayers & R. D. Hays (Eds.), Assessing quality of life in clinical trials (2nd ed.). Oxford: Oxford University Press.Google Scholar
- 20.Scott, N. W., Fayers, P. M., Aaronson, N. K., Bottomley, A., de Graeff, A., Groenvold, M., et al. (2010). Differential item functioning (DIF) analyses of health-related quality of life instruments using logistic regression. Health Quality Life Outcomes, 8, 81.Google Scholar
- 21.Groenvold, M., & Petersen, M. A. (2005). The role and use of differential item functioning (DIF) analysis of quality of life data from clinical trials. In R. D. Hays & P. Fayers (Eds.), Assessing quality of life in clinical trials (2nd ed.). Oxford: Oxford University Press.Google Scholar
- 22.Mellenberg, G. J. (1982). Contingency table models for assessing item bias. Journal of Educational Statistics, 7(2), 105–118.Google Scholar
- 26.Reeve, B. B., Hays, R. D., Bjorner, J. B., Cook, K. F., Crane, P. K., Teresi, J. A., et al. (2007). Psychometric evaluation and calibration of health-related quality of life item banks: Plans for the patient-reported outcomes measurement information system (PROMIS). Medical Care, 45(5 Suppl 1), S22–S31.CrossRefPubMedGoogle Scholar
- 32.Watt, T., Groenvold, M., Deng, N., Gandek, B., Feldt-Rasmussen, U., Rasmussen, A. K., Hegedüs, L., Bonnema, S.J., Bjorner, J.B. (2014). Confirmatory factor analysis of the thyroid-related quality of life questionnaire ThyPRO. Health and Quality of Life Outcomes (in press).Google Scholar
- 33.Zumbo, B. D. (1999). A handbook on the theory and methods of differential item functioning (DIF). Logistic regression modeling as a unitary framework for binary and Likert-type (ordinal) item scores (1st ed.). Ottawa, ON: Directorate of Human Resources Research and Evaluation, Department of National Defense.Google Scholar
- 38.Bjorner, J. B., & Pejtersen, J. H. (2010). Evaluating construct validity of the second version of the Copenhagen Psychosocial Questionnaire through analysis of differential item functioning and differential item effect. Scandinavian journal of public health, 38(3 Suppl), 90–105.CrossRefPubMedGoogle Scholar
- 40.Crane, P. K., Gibbons, L. E., Ocepek-Welikson, K., Cook, K., Cella, D., Narasimhalu, K., et al. (2007). A comparison of three sets of criteria for determining the presence of differential item functioning using ordinal logistic regression. Quality of Life Research, 16(Suppl 1), 69–84.CrossRefPubMedGoogle Scholar
- 44.Holland, P. W., & Thayer, D. T. (1988). Differential item performance and the Mantel-Haenzel procedure. In H. Wainer & H. I. Braun (Eds.), Test validity. NJ: Hillsdale.Google Scholar
- 47.SAS Institute Inc. (2011). SAS/STAT 9.3 User’s Guide. Cary: SAS Institute Inc.Google Scholar
- 50.Graf, H., Fast, S., Pacini, F., Pinchera, A., Leung, A., Vaisman, M., et al. (2011). Modified-release recombinant human TSH (MRrhTSH) augments the effect of 131I therapy in benign multinodular goiter: Results from a multicenter international, randomized, Placebo-Controlled Study. The Journal of Clinical Endocrinology & Metabolism, 96(5), 1368–1376.CrossRefGoogle Scholar