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The hunter syndrome-functional outcomes for clinical understanding scale (HS-FOCUS) questionnaire Evaluation of measurement properties

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


Wiklund, I., Raluy-Callado, M., Stull, D., Jangelind, Y., Whiteman, DAH., & Chen, W-H. (2013). The hunter syndrome-functional outcomes for clinical understanding scale (HS-FOCUS) questionnaire: Evaluation of measurement properties. Quality of Life Research, 22(4), 875-884. DOI: 10.1007/s11136-012-0196-5

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