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


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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

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