Cross-cultural adaptation and validation in spanish of the malocclusion impact questionnaire (MIQ).

BACKGROUND: The Malocclusion Impact Questionnaire (MIQ) is a condition-specific measure that assesses the impact of malocclusion on Oral Health-Related Quality of Life (OHRQoL). The aim of this study was to cross-culturally adapt the original version of MIQ into Spanish and to assess the acceptability, reliability and validity of this version in the Chilean population. METHODS: The MIQ was cross-culturally adapted for the Spanish language for Chile using recommended standards for the linguistic validation of instruments. To assess its psychometric properties, a cross-sectional study was carried out with 219 children aged 10 to 16 years from public schools in Puerto Montt, Chile, who completed the Chilean versions of the MIQ (MIQCh) and the Child Perceptions Questionnaire 11-14 (CPQ11-14). The presence and severity of malocclusions was determined through the Dental Aesthetic Index by a trained dentist. The MIQ was administrated a second time two weeks later. The reliability of the scale was assessed by analysis of its internal consistency (Cronbach's alpha) and reproducibility (Intraclass correlation coefficient - ICC). The validity of the construct was assessed by confirmatory factor analysis and known groups method. Criterion validity was assessed by calculating the Spearman correlation with the CPQ11-14. RESULTS: The content comparison of the back-translation with the original MIQ showed that all items except two were conceptually and linguistically equivalent. The cognitive debriefing showed a suitable understanding of the Chilean version. The MIQCh demonstrated good reliability, with Cronbach's alpha coefficient of 0.85 and ICC of 0.91. A moderate correlation was found between the MIQCh and CPQ11-14 (0.58). In the known groups comparison, children who felt that their teeth bothered them and/or affected their life obtained significantly higher scores on the MIQCh. The OHRQoL was worse when the severity of the malocclusion was greater (p = 0.03). CONCLUSIONS: The results support the applicability, reliability and validity of the Spanish version of MIQ for assessing OHRQoL in Chilean children with malocclusions.