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Rasch analysis of the short form 8-item Parkinson’s Disease Questionnaire (PDQ-8)

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Abstract

Purpose

To evaluate the Italian version of the 8-item Parkinson’s Disease Questionnaire (PDQ-8)—a subset of PDQ-39 (a 39-item health-related quality of life instrument for subjects with Parkinson’s Disease [PD])—through classical psychometric techniques and Rasch analysis.

Methods

Two convenience samples (100 PD subjects each) were observed consecutively from 2004 to 2006. One group completed the PDQ-8 nested within PDQ-39, the other, the stand-alone PDQ-8.

Results

Once verified that the two independent samples came from the same population and showed consistent item calibrations using differential item functioning analysis, the two groups were combined. Cronbach’s alpha was 0.72. According to Rasch analysis, the response scale of PDQ-8 could be simplified into a 3-category rating scale. After that, all the PDQ-8 items fitted the construct that the scale was intended to measure. Item separation reliability of PDQ-8 was 0.98 and person separation reliability was 0.70. Principal component analysis on the standardized residuals suggested a minor departure in the data from Rasch criteria (multidimensionality) and some marginal inter-item dependency.

Conclusions

The PDQ-8 embedded in the PDQ-39 presented psychometric properties similar to the stand-alone PDQ-8. Our results, while consistent with previous classical psychometric analyses, add information on the meaningfulness of PDQ-8 in people with PD. In particular, a simplification of its rating scale is recommended. Moreover, additional analyses should be performed in order to further check unidimensionality and local dependence, and try to improve item selection and scaling properties of the questionnaire. In order to use the PDQ-8 for clinical decision-making in reference to individuals, its reliability should first be increased.

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References

  1. Schrag, A., Jahanshahi, M., Quinn, N. (2000). How does Parkinson’s disease affect quality of life? A comparison with quality of life in the general population. Movement Disorders, 15, 1112–1118.

    Article  PubMed  CAS  Google Scholar 

  2. Damiano, A. M., Snyder, C., Strausser, B., Willian, M. K. (1999). A review of health-related quality-of-life concepts and measures for Parkinson’s disease. Quality of Life Research, 8, 235–243.

    Article  PubMed  CAS  Google Scholar 

  3. Marinus, J., Ramaker, C., van Hilten, J. J., Stiggelbout, A. M. (2002). Health related quality of life in Parkinson’s disease: a systematic review of disease specific instruments. Journal of Neurology, Neurosurgery, and Psychiatry, 72, 241–248.

    Article  PubMed  CAS  Google Scholar 

  4. Jenkinson, C., Fitzpatrick, R., Peto, V., Greenhall, R., Hyman, N. (1997). The Parkinson’s Disease Questionnaire (PDQ-39): development and validation of a Parkinson’s disease summary index score. Age and Ageing, 26, 353–357.

    Article  PubMed  CAS  Google Scholar 

  5. Peto, V., Jenkinson, C., Fitzpatrick, R. (1998). PDQ-39: a review of the development, validation and application of a Parkinson’s disease quality of life questionnaire and its associated measures. Journal of Neurology, 245(Suppl 1), S10–S14.

    Article  PubMed  Google Scholar 

  6. Jenkinson, C., Fitzpatrick, R. (2007). Cross-cultural evaluation of the short form 8-item Parkinson’s Disease Questionnaire (PDQ-8): results from America, Canada, Japan, Italy and Spain. Parkinsonism & Related Disorders, 13, 22–28.

    Article  Google Scholar 

  7. Katsarou, Z., Bostantjopoulou, S., Peto, V., Kafantari, A., Apostolidou, E., Peitsidou, E. (2004). Assessing quality of life in Parkinson’s disease: can a short-form questionnaire be useful? Movement Disorders, 19, 308–312.

    Article  PubMed  Google Scholar 

  8. Tan, L. C., Luo, N., Nazri, M., Li, S. C., Thumboo, J. (2004). Validity and reliability of the PDQ-39 and the PDQ-8 in English-speaking Parkinson’s disease patients in Singapore. Parkinsonism & Related Disorders, 10, 493–499.

    Article  Google Scholar 

  9. Tan, L. C., Lau, P. N., Au, W. L., Luo, N. (2007). Validation of PDQ-8 as an independent instrument in English and Chinese. Journal of the Neurological Sciences, 255, 77–80.

    Article  PubMed  Google Scholar 

  10. Hagell, P., McKenna, S. P. (2003). International use of health status questionnaires in Parkinson’s disease: translation is not enough. Parkinsonism & Related Disorders, 10, 89–92.

    Article  Google Scholar 

  11. Kim, M. Y., Dahlberg, A., & Hagell, P. (2006). Respondent burden and patient-perceived validity of the PDQ-39. Acta Neurologica Scandinavica, 113, 132–137.

    Article  PubMed  Google Scholar 

  12. Tesio, L. (2003). Measuring behaviours and perceptions: Rasch analysis as a tool for rehabilitation. Journal of Rehabilitation Medicine, 35, 105–115.

    Article  PubMed  Google Scholar 

  13. Wright, B. D., & Masters, G. N. (1982). Rating scale analysis. Chicago: Mesa Press.

    Google Scholar 

  14. Bond, T. G., &, Fox, C. M. (2001). Applying the Rasch model: fundamental measurement in the human sciences. Mahwah, NJ: Lawrence Erlbaum Associates.

    Google Scholar 

  15. Andresen, E. M. (2000). Criteria for assessing the tools of disability outcomes research. Archives of Physical Medicine and Rehabilitation, 81(Suppl 2), S15–S20.

    Article  PubMed  CAS  Google Scholar 

  16. Hughes, A. J., Daniel, S. E., Kilford, L., & Lees, A. J. (1992). Accuracy of clinical diagnosis of idiopathic Parkinson’s disease: a clinico-pathological study of 100 cases. Journal of Neurology, Neurosurgery, and Psychiatry, 55, 181–184.

    Article  PubMed  CAS  Google Scholar 

  17. Cardol, M., De Haan, R. J., De Jong, B. A., Van Den Bos, G. A., & De Groot, I. J. (2001). Psychometric properties of the Impact on Participation and Autonomy questionnaire. Archives of Physical Medicine and Rehabilitation, 82, 210–216.

    Article  PubMed  CAS  Google Scholar 

  18. Franchignoni, F., Ferriero, G., Giordano, A., Guglielmi, V., & Picco, D. (2007). Rasch psychometric validation of the Impact on Participation and Autonomy questionnaire in people with Parkinson’s disease. Europa Medicophysica, 43, 451–461.

    PubMed  CAS  Google Scholar 

  19. Fahn, S., Elton, R.L.; Members of the UPDRS Development Committee. (1987). Unified Parkinson’s Disease Rating Scale. In S. Fahn, C. D. Marsden, D. Calne, M. Goldstein (eds.), Recent developments in Parkinson’s Disease II (pp. 153–163). Florham Park, NJ: MacMillan Healthcare Information.

  20. Guillemin, F., Bombardier, C., & Beaton, D. (1993). Cross-cultural adaptation of health-related quality of life measures: literature review and proposed guidelines. Journal of Clinical Epidemiology, 46, 1417–1432.

    Article  PubMed  CAS  Google Scholar 

  21. Hagell, P., Whalley, D., McKenna, S. P., & Lindvall, O. (2003). Health status measurement in Parkinson’s disease: validity of the PDQ-39 and Nottingham Health Profile. Movement Disorders, 18, 773–783.

    Article  PubMed  Google Scholar 

  22. Bushnell, D. M., & Martin, M. L. (1999). Quality of life and Parkinson’s disease: Translation and validation of the US Parkinson’s Disease Questionnaire (PDQ-39). Quality of Life Research, 8, 345–350.

    Article  PubMed  CAS  Google Scholar 

  23. Streiner, D. L., & Norman, G. R. (Eds). (1995). Health measurement scales. A practical guide to their development and use, 2nd edn. Oxford: Oxford University Press.

    Google Scholar 

  24. Bland, J. M., & Altman, D. G. (1997). Cronbach’s alpha. BMJ, 314 (7080), 572.

    Google Scholar 

  25. Portney, L. G., & Watkins, M. P. (2000). Foundations of clinical research: Applications to practice, 2nd edn. Upper Saddle River, NJ: Prentice-Hall Health.

    Google Scholar 

  26. Linacre, J. M. (2004). A user’s guide to Winsteps. Rasch-model computer programs. Chicago, IL. http://www.winsteps.com/aftp/winsteps.pdf. Retrieved 10 March 2007.

  27. Linacre, J. M., & Wright, B. D. (1987). Item bias: Mantel-Haenszel and the Rasch model. http://www.rasch.org/memo39.pdf. Retrieved 30 December 2007.

  28. Linacre, J. M. (1999). Investigating rating scale category utility. Journal of Outcome Measurement, 3, 103–122.

    PubMed  CAS  Google Scholar 

  29. Zhu, W., Updyke, W.F., & Lewandowski, C (1997). Post-hoc Rasch analysis of optimal categorization of an ordered-response scale. Journal of Outcome Measurement, 1, 286–304.

    PubMed  CAS  Google Scholar 

  30. Linacre, J. M. (1994). Sample size and item calibration stability. Rasch Measurement Transactions, 7, 328.

    Google Scholar 

  31. Nunnally, J. C., & Bernstein, I. H. (1994). Psychometric theory, 3rd edn. New York: McGraw-Hill.

    Google Scholar 

  32. Wolfe, E. W., Smith, E. V. Jr. (2007). Instrument development tools and activities for measure validation using Rasch models: part I – instrument development tools. Journal of Applied Measurement, 8, 97–123.

    PubMed  Google Scholar 

  33. Lopez, W. (1996). Communication validity and rating scales. Rasch Measurement Transactions, 10, 482–483.

    Google Scholar 

  34. Ma, H. I., Hwang, W. J., & Chen-Sea, M. J. (2005). Reliability and validity testing of a Chinese-translated version of the 39-item Parkinson’s Disease Questionnaire (PDQ-39). Quality of Life Research, 14, 565–569.

    Article  PubMed  Google Scholar 

  35. Hagell, P., & Nygren, C. (2007). The 39-item Parkinson’s disease questionnaire (PDQ-39) revisited: implications for evidence-based medicine. Journal of Neurology, Neurosurgery, and Psychiatry, 78, 1191–1198.

    Article  PubMed  Google Scholar 

  36. Reeve, B. B., Hays, R. D., Bjorner, J. B., 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.

    Article  PubMed  Google Scholar 

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Authors and Affiliations

  1. Unit of Occupational Rehabilitation and Ergonomics, Fondazione Salvatore Maugeri, Clinica del Lavoro e della Riabilitazione, IRCCS, Via Revislate 13, 28010, Veruno, NO, Italy

    Franco Franchignoni & Giorgio Ferriero

  2. Bioengineering Service, Salvatore Maugeri Foundation, Clinica del Lavoro e della Riabilitazione, IRCCS, Veruno, NO, Italy

    Andrea Giordano

Authors
  1. Franco Franchignoni
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  2. Andrea Giordano
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  3. Giorgio Ferriero
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Correspondence to Franco Franchignoni.

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Franchignoni, F., Giordano, A. & Ferriero, G. Rasch analysis of the short form 8-item Parkinson’s Disease Questionnaire (PDQ-8). Qual Life Res 17, 541–548 (2008). https://doi.org/10.1007/s11136-008-9341-6

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  • DOI: https://doi.org/10.1007/s11136-008-9341-6

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