Development and Initial Validation of Quality-of-Life Questionnaires for Intermittent Exotropia

Abstract

Purpose We report the development and initial validation of patient–derived, health related quality of life (HRQOL) questionnaires for intermittent exotropia (IXT). Design Cross-sectional study Participants In a development phase, 27 children (aged 2–17 years) with IXT and one of their parents. In an initial validation phase, 33 children with IXT and 49 control children (aged 5–17 years) along with one parent for each child. Children in the control group had no strabismus or amblyopia. Methods Individual patient interviews generated 35 items for Child and Proxy (parental assessment of child’s HRQOL) questionnaires and 46 items for a Parent questionnaire. To reduce to a feasible number of items, questionnaires were administered to 5–17 year old children with IXT (n=15) and parents of 2–17 year old children with IXT (n=27). Responses were analyzed using standard item reduction methodology. Three final derived IXT questionnaires (IXTQ): Child, Proxy, and Parent (12, 12, and 17 items respectively) were administered to children with IXT and control children, and to parents of IXT and control children. Likert-type scales ranging from ‘never’ (score 100, best HRQOL) to ‘almost always’ (score 0, worst HRQOL) were used for responses. Main outcome measures Median scores for IXT and control groups, compared using Wilcoxon tests. Results Median Child scores were significantly lower (worse HRQOL) in the IXT group compared with the control group: 85 (quartiles 73–92) versus 92 (79–96); P=0.04. Median Proxy IXTQ scores were significantly lower for IXT children than controls: 83 (75–94) versus 98 (92–100); P<0.0001. Median Parent IXTQ scores were also significantly lower in the IXT group compared with the control group: 68 (quartiles 56–79) versus 93 (87–99); P<0.0001. Conclusions We have developed and validated a new 3-part patient-derived HRQOL questionnaire for children with IXT and their parents, comprising Child, Proxy and Parent questionnaires. These questionnaires detect reduced HRQOL in children with IXT as reported by the child themselves and as perceived by their parents (proxy report). Childhood IXT also appears to affect the HRQOL of the parents. The IXTQ HRQOL questionnaires may prove useful in the clinical assessment of IXT and for clinical trials.

Patient-reported outcome measures (PROMs) in paediatric ophthalmology: a systematic review

“…In this scenario, however, such an approach may result in measures that capture (in addition or solely) parental stress and impact on the family (eg, NLDO76–79). One instrument that we identified (IXTQ48 50) provides an example of how the assessment of parental anxieties and QoL can be helpfully separated from the child's with concurrent development of two complementary but distinct, respondent-targeted measures.…”

Childhood intermittent exotropia from a different angle: does severity affect quality of life?

“…The Intermittent Exotropia Questionnaire (IXTQ) is a condition-specific, patient-derived validated HRQOL questionnaire for children with IXT and their parents 9. Although other questionnaires, for example, VF-14 and PedsQL, have also been used to assess HRQOL in children with strabismus, they are not specific to IXT 10 11.…”

The impact of strabismus on quality of life in adults with and without diplopia: a systematic review

“…Carlton et al 8 identified four strabismus-and amblyopia-specific QoL questionnaires: the amblyopia and strabismus questionnaire 46 (A&SQ), the amblyopia treatment index, 11 the adult strabismus questionnaire [19][20], and the intermittent exotropia questionnaire. 22 The two strabismusspecific questionnaires, the A&SQ and AS-20, have both been shown to have better discriminatory ability when compared with the SF-12 and VFQ-25 18,46 for those with strabismus.…”