Development of the Malocclusion Impact Questionnaire (MIQ) to measure the oral health-related quality of life of young people with malocclusion: part 2 – cross-sectional validation

Philip E Benson,Nahush Shah,Zoe Marshman,Sarah R Baker,Susan J Cunningham,Samantha J Hodges,Fiona Gilchrist

doi:10.1080/14653125.2015.1114223

Abstract

Objective: To test the items, identified through qualitative inquiry that might form the basis of a new Malocclusion Impact Questionnaire (MIQ) to measure the oral health-related quality of life (OHQoL) of young people with malocclusion. Methods: Piloting with 13 young people reduced the number of items from 37 to 28. Cross-sectional testing involved a convenience sample aged 10–16 years, attending the Orthodontic Department of the Charles Clifford Dental Hospital, Sheffield. The fit and function of the initial MIQ questions were examined using item response theory. Results: 184 participants (113 females; 71 males) completed a questionnaire (response 85%), seven participants were excluded due to missing responses. The mean age of participants was 12·9 years (SD 1·4) and they had a wide range of malocclusions. The majority were White British (67·4%). Data from 47 participants were used to analyse test–retest reliability. Rasch analysis was undertaken, which further reduced the number of items in the questionnaire from 28 to 17. Unidimensionality of the scale was confirmed. The analysis also identified that the original 5-point response scale could be reduced to three points. The new measure demonstrated good criterion validity (r = 0·751; P < 0·001) and construct validity with the two global questions (‘Overall bother’ ρ = 0·733 and ‘Life overall’ ρ = 0·701). Internal consistency (Cronbach's alpha = 0·906) and test–retest reliability Intraclass correlation coefficient (ICC = 0·78; 95% CI 0·61–0·88) were also good. Conclusion: Cross-sectional testing has shown the new MIQ to be both valid and reliable. Further evaluation is required to confirm the generalisability as well as the ability of the new measure to detect change over time (responsiveness).

Highlights

Doubts have been expressed about the suitability of some of the current generic measures for assessing oral health-related quality of life (OHQoL) in young people seeking orthodontic treatment (Marshman et al, 2010)
In Part 1 of this report, we described the first two stages of developing a Malocclusion Impact Questionnaire (MIQ) to measure the OHQoL of young people with malocclusion, which involved:
Stevens found that common adverbs and adverbial phrases used by the young people to describe their health-related quality of life (HRQoL) were ‘a little bit’, ‘a bit’, ‘quite’ and ‘very’; these words were incorporated into a 5-point scale to describe the severity of their impact

Summary

Introduction

Doubts have been expressed about the suitability of some of the current generic measures for assessing OHQoL in young people seeking orthodontic treatment (Marshman et al, 2010). In Part 1 of this report, we described the first two stages of developing a Malocclusion Impact Questionnaire (MIQ) to measure the OHQoL of young people with malocclusion, which involved:. . Specifying measurement goals: using descriptors appropriate for measuring the oral health-related quality of life (HRQoL) in adolescents with malocclusion;. . Item generation: populating the measure with suitable items on the basis of qualitative inquiry. We describe the further development of MIQ involving: Address for correspondence: Philip E.

Methods

Results

Discussion

Conclusion