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

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. 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 (MIQ ) and the Child Perceptions Questionnaire 11-14 (CPQ ). 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 CPQ . 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 MIQ demonstrated good reliability, with Cronbach's alpha coefficient of 0.85 and ICC of 0.91. A moderate correlation was found between the MIQ and CPQ (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 MIQ . The OHRQoL was worse when the severity of the malocclusion was greater (p = 0.03). The results support the applicability, reliability and validity of the Spanish version of MIQ for assessing OHRQoL in Chilean children with malocclusions.