Since 1980, several studies have introduced the impact of oral and maxillofacial problems on quality of life. 26 However, since most of the tools used in these studies were in English language, they must be translated, adopted, and validated to be feasible and applicable when employed in non-English speaking population.27 The CPQ11–14 ISF-16 has been broadly used in studies on malocclusion and OHRQoL.27,28 This questionnaire has been employed for children with dental and maxillofacial malformations.5
The CPQ11–14 ISF-16 is a suitable tool to assess the perception of children and adolescents about the condition of their mouth and jaw. To facilitate the use of this questionnaire in population-based surveys, a short 16-item form of this questionnaire was proposed while retaining psychometric properties.6 In this study, the aim of translating the CPQ11-14 ISF-16 questionnaires into Persian was cultural adaptation and validation in a population of adolescents with malocclusion. In order to evaluate the appropriate equivalence between the translated version and the original version, four stages of equivalence including semantic, idiomatic, experiential, and conceptual were considered.10 The process of translation and cultural adaptation was completely performed regarding the four stages proposed by Herdman et al. 29
Cronbach's alpha correlation coefficient in the Persian version of CPQ11-14 ISF-16 was 0.855, which indicates sufficient internal reliability of the Persian version of the present questionnaire. This rate is similar to the results of studies performed in other countries. 2,3,5,8,11,22,23
Participants were asked to complete the questionnaires in person and in a non-clinical setting where an acquainted assistant was present. Since the participants in this study were not adults and were accompanied by their parents or guardians, their responses may have been possibly influenced by them.31 However, the results of a study refuted the impact of parents' responses on children while completing the OHRQoL questionnaire. 32
It should be noted that it might be possible that participants at this age-range become bored while filling out two questionnaires at the same time, and there will be a notion that this would lead them to fill out the questionnaires randomly and not precisely. However, the test-retest reliability results showed that the probability of random responses could be ignored.2 Test-retest reliability in this study for the total scale was 0.85.
This value for the original version of the 16-question form was 0.77 in Canada and in other studies, it was reported to be 0.78 in Saudi Arabia, 0.97 in Brazil, and 0.72 in Greece.2,5,11,23 In this study, two dimensions of the Persian version of CPQ11-14 ISF-16 were extracted using Exploratory Factor Analysis (EFA). The first dimension, Well-being, included questions 1, 2, 3, 4, 5, 6, 7, and 8, and the second dimension, Symptom and function, included questions 9, 10, 11, 12, 13, 14, 15, 16, and 17. Similarly, in the study of Thomson et al.3, two dimensions of CPQ11-14 ISF-16 questionnaire were extracted. However, in the original version of CPQ11-14 ISF-16, four dimensions were extracted. 5
Construct validity of the Persian version of CPQ11-14 ISF-16 was performed by evaluating the correlation between the average score of the two global questions and the total score and the average score of each of the dimensions of well-being and symptom and function. The results showed that there was a strong significant correlation between these three items. These results were similar to the results presented by several studies. 7,11,33 However, the Arabic version did not report any correlation between well-being and symptom and function and global questions.18
To evaluate the criterion validity, the Persian version of CPQ11-14 ISF-16 was compared with the Persian version of the PIDAQ questionnaire. The validity and reliability of the Persian version of the PIDAQ questionnaire has already been evaluated in the Iranian population.25 Moreover, the results showed a high correlation between PIDAQ questionnaire and CPQ11-14 ISF-16 questionnaire and two dimensions of well-being and symptom and function.