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Brief Report
April 2015

Evaluation of the Intermittent Exotropia Questionnaire Using Rasch Analysis

David A. Leske, MS1; Jonathan M. Holmes, BM, BCh1; B. Michele Melia, ScM2; et al for the Pediatric Eye Disease Investigator Group
Author Affiliations
  • 1Department of Ophthalmology, Mayo Clinic, Rochester, Minnesota
  • 2Jaeb Center for Health Research, Tampa, Florida
JAMA Ophthalmol. 2015;133(4):461-465. doi:10.1001/jamaophthalmol.2014.5622

Importance  The Intermittent Exotropia Questionnaire (IXTQ) is a patient, proxy, and parental report of quality of life specific to children with intermittent exotropia. We refine the IXTQ using Rasch analysis to improve reliability and validity.

Observation  Rasch analysis was performed on responses of 575 patients with intermittent exotropia enrolled from May 15, 2008, through July 24, 2013, and their parents from each of the 4 IXTQ health-related quality-of-life questionnaires (child 5 through 7 years of age and child 8 through 17 years of age, proxy, and parent questionnaires). Questionnaire performance and structure were confirmed in a separate cohort of 379 patients with intermittent exotropia. One item was removed from the 12-item child and proxy questionnaires, and response options in the 8- to 17-year-old child IXTQ and proxy IXTQ were combined into 3 response options for both questionnaires. Targeting was relatively poor for the child and proxy questionnaires. For the parent questionnaire, 3 subscales (psychosocial, function, and surgery) were evident. One item was removed from the psychosocial subscale. Resulting subscales had appropriate targeting.

Conclusions and Relevance  The Rasch-revised IXTQ may be a useful instrument for determining how intermittent exotropia affects health-related quality of life of children with intermittent exotropia and their parents, particularly for cohort studies.