The Hunter Syndrome-Functional Outcomes for Clinical Understanding Scale (HS-FOCUS) Questionnaire: evaluation of measurement properties
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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.
KeywordsHunter 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
Change in Health
Childhood Health Assessment Questionnaire
Childhood Health Questionnaire
Child Health Questionnaire-Child Form
Child Health Questionnaire-Parent Form
Disability Index Score
Forced expiratory volume
Functional Independence Measure
Forced vital capacity
General Health Perceptions
Health-related quality of life
Hunter Syndrome-Functional Outcomes for Clinical Understanding Scale
Health Utilities Index
Intraclass correlation coefficient
- MPS II
Mucopolysaccharidosis type II
Pediatric Outcomes Data Collection Instrument
Role/Social–Emotional and the Role/Social–Behavioral
World Health Organization International Classification of Impairment, Disability and Handicap
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