Quality of Life Research

, Volume 22, Issue 4, pp 875–884 | Cite as

The Hunter Syndrome-Functional Outcomes for Clinical Understanding Scale (HS-FOCUS) Questionnaire: evaluation of measurement properties

  • Ingela Wiklund
  • Mireia Raluy-Callado
  • Donald E. Stull
  • Yvonne Jangelind
  • David A. H. Whiteman
  • Wen-Hung Chen
Original Paper



This study was to conduct the psychometric validation of the patient and parent versions of the Hunter Syndrome-Functional Outcomes for Clinical Understanding Scale (HS-FOCUS).


Data collected in a 53-week placebo-controlled multinational trial were used to evaluate item performance and reliability, validity, and ability to detect change of the six HS-FOCUS function domains.


HS-FOCUS was completed by 49 patients above 12 years old and 84 parents. Floor effects and high average inter-item correlations suggested that some items were less informative or redundant. For both patients and parents, the internal consistency and test–retest reliability met the >0.70 criteria for all domains except for the breathing, sleeping, and schooling/work in patients. Construct validity showed moderate to high correlations with CHAQ, CHQ, and HUI3 in activity-related concepts. Significant differences in domain scores were found in most domains among severity in disability measured by CHAQ DIS. Significant differences in HS-FOCUS change scores were found in patients whose CHAQ DIS score also changed.


Psychometric validation of the HS-FOCUS demonstrates it is a reliable, valid, and responsive instrument that can be applied in clinical trials or disease registries. Findings on the individual item performance suggest some items could be removed without compromising its validity.


Hunter syndrome Mucopolysaccharidosis type II Lysosomal storage disease Patient-reported outcomes Hunter Syndrome-Functional Outcomes for Clinical Understanding Scale (HS-FOCUS) 



Six-minute walk test


Analysis of covariance


Analysis of variance


Bodily Pain


Change in Health


Childhood Health Assessment Questionnaire


Childhood Health Questionnaire


Child Health Questionnaire-Child Form


Child Health Questionnaire-Parent Form


Disability Index Score


Family Activities


Family Cohesion


Forced expiratory volume


Functional Independence Measure


Forced vital capacity




Global Behavior


General Health Perceptions


Health-related quality of life


Hunter syndrome


Hunter Syndrome-Functional Outcomes for Clinical Understanding Scale


Health Utilities Index




Intraclass correlation coefficient


Mental Health


Mucopolysaccharidosis type II


Parental Impact–Emotional


Physical Functioning


Pediatric Outcomes Data Collection Instrument


Patient-reported outcome


Parental Impact–Time






Role/Social–Emotional and the Role/Social–Behavioral




Standard deviation


Self Esteem


World Health Organization International Classification of Impairment, Disability and Handicap


  1. 1.
    Alcalde-Martin, C., Muro-Tudelilla, J. M., Cancho-Candela, R., Gutierrez-Solana, L. G., Pintos-Morell, G., Marti-Herrero, M., et al. (2010). First experience of enzyme replacement therapy with idursulfase in Spanish patients with Hunter syndrome under 5 years of age: Case observations from the Hunter Outcome Survey (HOS). European Journal of Medical Genetics, 53(6), 371–377.PubMedCrossRefGoogle Scholar
  2. 2.
    Martin, R., Beck, M., Eng, C., Giugliani, R., Harmatz, P., Munoz, V., et al. (2008). Recognition and diagnosis of mucopolysaccharidosis II (Hunter syndrome). Pediatrics, 121(2), e377–e386.PubMedCrossRefGoogle Scholar
  3. 3.
    Muenzer, J., Beck, M., Eng, C. M., Escolar, M. L., Giugliani, R., Guffon, N. H., et al. (2009). Multidisciplinary management of Hunter syndrome. Pediatrics, 124(6), e1228–e1239.PubMedCrossRefGoogle Scholar
  4. 4.
    Young, I. D., & Harper, P. S. (1982). Mild form of Hunter’s syndrome: Clinical delineation based on 31 cases. Archives of Disease in Childhood, 57(11), 828–836.PubMedCrossRefGoogle Scholar
  5. 5.
    Young, I. D., & Harper, P. S. (1983). The natural history of the severe form of Hunter’s syndrome: A study based on 52 cases. Developmental Medicine and Child Neurology, 25(4), 481–489.PubMedCrossRefGoogle Scholar
  6. 6.
    Keilmann, A., Nakarat, T., Bruce, I. A., Molter, D., Malm, G., & on behalf of the HOS Investigators. Hearing loss in patients with mucopolysaccharidosis II: Data from HOSthe hunter outcome survey.Google Scholar
  7. 7.
    Pascolini, D., & Smith, A. (2009). Hearing impairment in 2008: A compilation of available epidemiological studies. International Journal of Audiology, 48(7), 473–485.PubMedCrossRefGoogle Scholar
  8. 8.
    World Health Organization (WHO). (1999). WHO ear and hearing disorders survey protocol for a population-based survey of prevalence and causes of deafness and hearing impairment and other ear disorders. Retrieved April 14, 2011, from http://whqlibdoc.who.int/hq/1999/WHO_PBD_PDH_99.8(1).pdf.
  9. 9.
    Singh, G., Athreya, B. H., Fries, J. F., & Goldsmith, D. P. (1994). Measurement of health status in children with juvenile rheumatoid arthritis. Arthritis and Rheumatism, 37(12), 1761–1769.PubMedCrossRefGoogle Scholar
  10. 10.
    Tran, K. T., Gold, K. F., Stephens, J. M., Kimura, A., & Muenzer, J. The development and validation of the hunter syndrome—functional outcomes for clinical understanding scale.Google Scholar
  11. 11.
    Abt. Associates. (2004). Clinical trials. Confirmatory validation study of the CHAQ. Video documentation of functional tasks, and development of a new supplement Questionnaire to assess functional status in hunter syndrome. Final Report.Google Scholar
  12. 12.
    Giannini, E. H., Ruperto, N., Ravelli, A., Lovell, D. J., Felson, D. T., & Martini, A. (1997). Preliminary definition of improvement in juvenile arthritis. Arthritis and Rheumatism, 40(7), 1202–1209.PubMedGoogle Scholar
  13. 13.
    Landgraf, J. M., Abetz, L. N., & Ware, J. E. (1999). The CHQ user’s manual. Boston: The Health Institute, New England Medical Center.Google Scholar
  14. 14.
    Valayannopoulos, V., de Blic, J., Mahlaoui, N., Stos, B., Jaubert, F., Bonnet, D., et al. (2010). Laronidase for cardiopulmonary disease in Hurler syndrome 12 years after bone marrow transplantation. Pediatrics, 126(5), e1242–e1247.PubMedCrossRefGoogle Scholar
  15. 15.
    McGovern, M. M., Wasserstein, M. P., Giugliani, R., Bembi, B., Vanier, M. T., Mengel, E., et al. (2008). A prospective, cross-sectional survey study of the natural history of Niemann-Pick disease type B. Pediatrics, 122(2), e341–e349.PubMedCrossRefGoogle Scholar
  16. 16.
    Horsman, J., Furlong, W., Feeny, D., & Torrance, G. (2003). The health utilities index (HUI): Concepts, measurement properties and applications. Health and Quality of Life Outcomes, 1, 54.PubMedCrossRefGoogle Scholar
  17. 17.
    StataCorp. (2009). Stata statistical software: Release 11. College Station, TX: StataCorp LP.Google Scholar
  18. 18.
    Cronbach, L. (1951). Coefficient alpha and the internal structure of tests. Psychometrika, 16, 297–334.CrossRefGoogle Scholar
  19. 19.
    Hays, R. D., & Revicki, D. A. (2005). Assessing reliability and validity of measurement in clinical trials. In P. Fayers & R. D. Hays (Eds.), Quality of life assessment in clinical trials: Methods and practice (2nd ed.). New York: Oxford University Press.Google Scholar
  20. 20.
    Nunnally, J. C., & Bernstein, I. H. (1994). Psychometric theory (3rd ed.). New York: McGraw-Hill.Google Scholar
  21. 21.
    Dempster, H., Porepa, M., Young, N., & Feldman, B. M. (2001). The clinical meaning of functional outcome scores in children with juvenile arthritis. Arthritis and Rheumatism, 44(8), 1768–1774.PubMedCrossRefGoogle Scholar
  22. 22.
    Leidy, N. K., Revicki, D. A., & Geneste, B. (1999). Recommendations for evaluating the validity of quality of life claims for labeling and promotion. Value Health, 2(2), 113–127.PubMedCrossRefGoogle Scholar
  23. 23.
    Rutten-van Molken, M., Roos, B., & Van Noord, J. A. (1999). An empirical comparison of the St George’s Respiratory Questionnaire (SGRQ) and the Chronic Respiratory Disease Questionnaire (CRQ) in a clinical trial setting. Thorax, 54(11), 995–1003.PubMedCrossRefGoogle Scholar
  24. 24.
    Daltroy, L. H., Liang, M. H., Fossel, A. H., & Goldberg, M. J. (1998). The POSNA pediatric musculoskeletal functional health questionnaire: Report on reliability, validity, and sensitivity to change. Pediatric Outcomes Instrument Development Group. Pediatric Orthopaedic Society of North America. Journal of Pediatric Orthopedics, 18(5), 561–571.PubMedGoogle Scholar
  25. 25.
    Keith, R. A., Granger, C. V., Hamilton, B. B., & Sherwin, F. S. (1987). The functional independence measure: A new tool for rehabilitation. Advances in Clinical Rehabilitation, 1, 6–18.PubMedGoogle Scholar

Copyright information

© Springer Science+Business Media B.V. 2012

Authors and Affiliations

  • Ingela Wiklund
    • 1
  • Mireia Raluy-Callado
    • 1
  • Donald E. Stull
    • 2
  • Yvonne Jangelind
    • 3
  • David A. H. Whiteman
    • 4
  • Wen-Hung Chen
    • 5
  1. 1.United BioSource CorporationLondonUK
  2. 2.RTI Health Solutions, The Pavilion, Towers Business ParkManchesterUK
  3. 3.StockholmSweden
  4. 4.Shire AG, Business Park Terre-BonneEysinsSwitzerland
  5. 5.United BioSource CorporationBethesdaUSA

Personalised recommendations