Qual Life Res DOI 10.1007/s11136-014-0807-4
BRIEF COMMUNICATION
Cross-cultural adaptation and validation of the Italian Psychosocial Impact of Dental Aesthetics Questionnaire (PIDAQ) Rosaria Bucci • Roberto Rongo • Eugenio Zito • Angela Galeotti • Rosa Valletta • Vincenzo D’Anto`
Accepted: 15 September 2014 Ó Springer International Publishing Switzerland 2014
Abstract Purpose To validate and cross-culturally adapt the Italian version of the Psychological Impact of Dental Aesthetics Questionnaire (PIDAQ) among Italian young adults. Methods After translation, back translation, and crosscultural adaptation of the English PIDAQ, a first version of the Italian questionnaire was pretested. The final Italian PIDAQ was administered to 598 subjects aged 18–30 years, along with two other instruments: the aesthetic component of the index of orthodontic treatment need (IOTN-AC) and the perception of occlusion scale (POS), which identified the self-reporting grade of malocclusion. Structural validity was assessed by means of factorial analysis, internal consistency was measured with Cronbach’s alpha coefficient (a), convergent validity was assessed by means of Spearman correlation, and test–retest reliability was calculated with intra-class correlation coefficient (ICC) and standard measurement error.
Rosaria Bucci and Roberto Rongo have contributed equally to this work. R. Bucci R. Rongo R. Valletta V. D’Anto` (&) Department of Neuroscience, Reproductive Sciences and Oral Sciences, School of Orthodontics, University of Naples ‘‘Federico II’’, Via Pansini 5, 80131 Naples, Italy e-mail: [email protected] E. Zito Department of Translational Medical Sciences, University of Naples ‘‘Federico II’’, Via Pansini 5, 80131 Naples, Italy A. Galeotti V. D’Anto` Division of Dentistry, Department of Pediatric Surgery, ‘‘Bambino Gesu`’’ Children’s Hospital, Viale di San Paolo, 15, 00146 Rome, Italy
Criterion validity was evaluated by multivariate and univariate analysis of variance with Bonferroni post hoc tests. Results The a of the Italian PIDAQ domains ranged between 0.79 and 0.92. The ICC was between 0.81 and 0.90. The mean scores of each PIDAQ domain showed a statistically significant difference when analysed according to the IOTN-AC and POS scores. Conclusion The satisfactory psychometric properties make PIDAQ a usable tool for future studies on oral healthrelated quality of life among Italian young adults. Keywords Quality of life in orthodontics Cross-cultural adaptation Questionnaire validation Young adults Aesthetics
Introduction Even though malocclusion cannot be considered a lifethreatening disease, the self-perception of dental aesthetics plays a crucial role in quality of life (QoL) [1, 2]. The recent increase in demand for orthodontic treatment may be ascribed to the greater attention on the aesthetic and social implications of the dental issues rather than the significant worsening of health status [3–5]. However, the traditional tools adopted by the clinicians to assess orthodontic treatment need are based on ideal concepts of occlusion and aesthetics [6], neglecting the effects of malocclusion on patients’ QoL [7–9]. Hence, it becomes critical to have a tool able to correctly determine patients’ perceptions of malocclusion. The Psychosocial Impact of Dental Aesthetics Questionnaire (PIDAQ) is a specific questionnaire, developed by Klages et al. [10]. It is composed of 23 items, divided into four domains: dental self-confidence (DSC, 6 items),
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social impact (SI, 8 items), psychological impact (PI, 6 items), and aesthetic concern (AC, 3 items). The possible responses for each item are as follows: zero = not at all; one = a little; two = somewhat; three = strongly; and four = very strongly. Differently from the other domains, the items of the DSC show positive meaning and interpretation. The PIDAQ can be used to assess orthodontic treatment need and to evaluate changes in oral health-related quality of life (OHRQoL) due to the orthodontic treatment [10]. Its use is widespread as it has already been translated in several languages [11–15], but not in Italian. Hence, the aim of this study was to translate and cross-culturally adapt the PIDAQ into the Italian language and to validate the questionnaire among Italian young adults, in order to provide a valid instrument for OHRQoL studies. The hypotheses were that the Italian PIDAQ had four different domains, as in the original instrument, each with a Cronbach’s alpha coefficient for the subscales (a) [ 0.79. In addition SI, PI, AC, and the reversed DSC were expected to have a positive correlation (Spearman correlation coefficient r [ 0.4) with two scales, the aesthetic component of the index of orthodontic treatment need (IOTN-AC) [16] and the perception of occlusion scale (POS) [17, 18] used for the self-rating of the malocclusion, as suggested by other authors [10–15].
Subjects and methods Translation Four orthodontic postgraduate students, proficient in English and Italian and familiar with the QoL terminology and instruments, independently translated the PIDAQ from English to Italian. Back translation One English teacher, naı¨ve to the QoL terminology, blinded to the purpose of the study, and with no knowledge of the original English questionnaire, back-translated the Italian version of the PIDAQ into English.
items in the Italian questionnaire, comparing those to the English version. After these phases, the first version of the Italian PIDAQ was created. Pretest The first version of the Italian PIDAQ was pilot tested on a convenience sample of 30 volunteers (17 females and 13 males), aged 18–30 years, recruited from the University of Naples ‘‘Federico II’’, Italy. The pilot test was performed by a single investigator (RB), through a direct interview, to assess possible difficulties in understanding the questionnaire. At the end of this phase, no adjustments were made to the initial version of the Italian PIDAQ. Translated version of PIDAQ The validity and reliability assessment of the Italian PIDAQ were carried out on a convenience sample of 598 young adults aged 18–30 years (296 females mean age 22.6 ± 3.1; 302 males mean age 22.8 ± 3.2) from the Campania area (Italy). The Italian PIDAQ was administered along with two standardized instruments, which aimed to correctly assess the self-reported degree of malocclusion: IOTN-AC and POS. The IOTN-AC is composed of 10 black and white photographs representing different kinds and degrees of malocclusion. The subjects were asked to indicate which photograph best represented their own teeth. The POS is a self-reported scale, composed of six statements based on dental aesthetic features of the frontal teeth. Intellectual and/or physical inability to answer the questionnaire, previous orthodontic treatment, and the presence of cavities, missing or fractured teeth and dark areas on the frontal teeth were considered exclusion criteria since they could influence the self-assessment of the malocclusion. Moreover, dentists and dentistry students were excluded due to their specific knowledge of the field. For the test–retest reliability assessment, 75 subjects were randomly selected to respond to the questionnaire a second time, at least 10 days after the first administration.
Cultural adaptation/committee review
Statistical analysis
A committee of three orthodontists and a psychologist, all fluent in English and familiar with QoL tools, adapted the Italian questionnaire in order to improve the semantic equivalence of meaning between the two English versions. Another committee of two experts in QoL and oral health evaluated the meaning and the importance of the
The Statistical Package for Social Science (SPSS Inc., Windows Release 19.0, Chicago, Illinois, USA) and the Statistical Analysis Software, version 9.3 (SAS Inc., Cary, NC, USA) were used to perform the statistical analysis. To facilitate the interpretation of the results, the scores of the DSC were reversed.
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Validity The structural validity of the PIDAQ was assessed using explanatory and confirmatory factor analysis. The criterion validity was determined by means of multivariate and univariate analysis of variance, with Bonferroni post hoc tests, evaluating the scores of each PIDAQ domain according to IOTN-AC and POS scores. The level of significance was set at P \ 0.05. Convergent validity was assessed by means of the Spearman correlation (r) between PIDAQ and IOTN-AC and POS. Reliability The internal consistency was calculated using the Cronbach’s alpha coefficient (a) for the subscales. A sample of 598 subjects each responding to 3, 6, 8 items, as PIDAQ domains, achieves 100 % power to detect the difference between the null hypothesis of a = 0.7 and the alternative hypothesis of a = 0.79 with P \ 0.05. The reproducibility was assessed as test–retest reliability on a sample of 75 subjects by means of intra-class correlation coefficient (ICC), standard measurement error (SME) and limits of agreement (LOA). A sample of 75 subjects with two observations per subject produces a twosided 95 % confidence interval with a width of 0.16 when ICC = 0.81 and a two-sided 95 % confidence interval with a width of 0.089 when ICC = 0.90, with P \ 0.05.
Results Cross-cultural adaptation During the cross-cultural adaptation, semantic and conceptual equivalence were reached using the same domains of the original questionnaire. Moreover, the pretest analysis demonstrated that young Italian adults could easily understand the questionnaire. Therefore, the cross-cultural adaptation resulted in a tool that was ready to be submitted. Validity The explanatory factor analysis detected four factors, which explained the 67.9 % of the variance reproducing the same division of items for groups of the original PIDAQ. The confirmatory factor analysis proved that the tested model had a high model fit indices (comparative fit index = 0.92, Table 1). According to the IOTN-AC scores, the participants were divided into four groups. The mean scores of each PIDAQ domain showed a statistically significant difference when
compared according to the IOTN-AC scores (Table 2). Similarly, the subjects were divided into four groups according to the POS scores, and the four PIDAQ domains demonstrated statistically significant differences when divided by the POS scores (Table 3). The Spearman coefficient for each domain ranged between 0.49 (SI) and 0.60 (AC) for the IOTN-AC and between 0.48 (DSC) and 0.64 (AC) for the POS (Tables 2, 3). Reliability The internal consistency measured between 0.79 (PI) and 0.92 (AC). Test–retest reliability ranged from 0.81 (AC) to 0.90 (DSC), and the percentage of difference in the LOA range was between 90.7 % (DSC) and 97.3 % (SI, PI) (Table 1).
Discussion The PIDAQ questionnaire is considered a valid instrument to assess the OHRQoL among young adults [10], but it has not yet been translated into the Italian language. During the cross-cultural adaptation, there was no need to apply modifications to the first-structured version of the Italian PIDAQ probably due to a substantial affinity between the European sociocultural contexts where the questionnaires were developed and tested. On the contrary, the Chinese PIDAQ cross-cultural adaption required several drafts before constructing a final version [11]. The factorial analysis of the Italian PIDAQ confirmed a fourdomain structure, similar to the original one. Moreover, the statistical analysis supported the hypotheses of the satisfactory psychometric properties of the questionnaire. The statistically significant results of both univariate and multivariate analysis and the increasing of PIDAQ values together with the increasing of the reported grade of malocclusion (Tables 2, 3) demonstrate the ability of the Italian PIDAQ to discriminate between different levels of self-reported malocclusion. Similar results were found in the original paper [10] when using the POS and the IOTN-AC, and in the Chinese PIDAQ translation [11] in which the authors adopted the same protocol to assess the criterion validity. However, similar results were also found in other PIDAQ validations [12–15] in which an objective assessment of the severity of malocclusion was performed. Regarding reliability, both a and ICC were satisfactory and comparable to those of the original questionnaire [10]. Since the association between self-esteem and the malocclusion effects on the OHRQoL was proved [19], the selfreported level of malocclusion should be integrated with an evaluation of self-esteem and self-concept in future studies.
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4.3 ± 4.9
4.2 ± 3.7
2.6 ± 3.5
Social impacts (8 items)
Psychological impacts (8 items)
Aesthetic impacts (8 items)
0–12
0–17
0–21
0–24
Range
0.92
0.79
0.86
0.90
a
0.86–0.91
0.72–0.79
0.82–0.86
0.88–0.90
a if item deleted
0.79–0.88
0.34–0.69
0.49–0.79
0.66–0.81
Range of interitem correlation
0
0
0
0
MI (%)
0.81(0.72–0.88)
0.84(0.76–0.90)
0.88(0.82–0.93)
0.90(0.84–0.93)
ICC (95 %CI)
1.52
1.48
2.07
1.70
SME
4.23
4.10
5.76
4.73
SDC
Test–retest reliability (N = 75)
0.07
-0.11
-0.70
-0.15
Paired difference mean
-0.13–0.26
-0.45–0.24
-0.32–0.18
-0.58–0.29
95 %CI
0.63
0.38
0.6
0.78
P
0
0
0
0
MI (%)
-1.61–1.75(95 %)
-3.03–2.82(97 %)
-2.19–2.05(97 %)
-3.48–3.54(91 %)
LOA
1
Scores have been reversed
P statistical significance of the paired t test for each domain Confirmatory factor analysis: CFI comparative fit index = 0.92, RMSR root mean square residual = 0.07, SRMSR standardized RMSR = 0.07, RMSEA root mean square error of approximation = 0.10
pffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffi a Cronbach’s alpha, MI percentage of missing items, ICC intra-class correlation, SME standard measurement error was calculated as SD ð1 ICCÞ, SDC smallest detectable change was calculated as 1.96 MEH2
LOA Limits of agreement were calculated as paired difference mean ± 1.96 standard deviation (percentage within LOA)
11.6 ± 5.4
Mean ± SD
Internal consistency (N = 598)
Dental selfconfidence (6 items)
Domain1
Table 1 Internal consistency (N = 598) and test–retest reliability (N = 75) for the PIDAQ domains
Qual Life Res
Qual Life Res Table 2 Results of multivariate and univariate analysis of variance of the PIDAQ scores according to the different IOTN-AC scores, and Spearman coefficient of correlation between the PIDAQ domains and IOTN-AC IOTN-AC
Scores of PIDAQ (mean ± SD)
Score
Dental self-confidence ,
***
Social impact***
Psychological impact***
Aesthetic concern***
1 (n = 199)
9.1 ± 4.4a
1.9 ± 2.9a
2.5 ± 2.6a
0.7 ± 1.4a
2 (n = 169)
a
b
b
1.2 ± 1.6a
c
9.7 ± 4.6
3.4 ± 3.9
3.5 ± 2.7
3 (n = 121) C4 (n = 109)
12.8 ± 4.0 17.6 ± 4.7c
4.9 ± 4.1 9.4 ± 6.2d
4.7 ± 3.0 8.1 ± 4.6d
3.7 ± 3.2b 7.0 ± 4.2c
Spearman correlation
r = 0.53***
r = 0.49***
r = 0.51***
r = 0.60***
a,b,c,d
b
c
Bonferroni post hoc test, different letters intra-domain indicate statistically significant differences among scores
*** P \ 0.001
Scores have been reversed
Table 3 Results of multivariate and univariate analysis of variance of the PIDAQ scores according to the different POS scores, and Spearman coefficient of correlation between the PIDAQ domains and POS POS
Scores of PIDAQ (mean ± SD)
score
Dental self-confidence , *** a
Social impact*** 1.6 ± 2.4
a
Psychological impact*** 2.3 ± 2.4
Aesthetic concern***
a
0.6 ± 1.2a
0–1 (n = 205)
9.3 ± 4.2
2–4 (n = 213)
10.1 ± 4.9a
3.8 ± 4.0b
3.7 ± 2.7b
1.4 ± 1.8b
5–8 (n = 114)
13.9 ± 3.5
b
5.5 ± 3.5
c
5.0 ± 2.9
c
4.9 ± 3.1c
C9 (n = 66)
19.5 ± 4.3
c
12.4 ± 6.1
d
10.7 ± 4.0
d
8.6 ± 4.2d
Spearman’s correlation
r = 0.48***
a,b,c,d
r = 0.53***
r = 0.56***
r = 0.64***
Bonferroni post hoc test, different letters intra-domain indicate statistically significant differences among scores
*** P \ 0.001
Scores have been reversed
One limitation of this study was the lack of investigation about the responsiveness of the Italian PIDAQ.
Conclusion The Italian PIDAQ showed satisfactory validity and reliability. Therefore, its good psychometric properties make it a suitable tool for the assessment of psychosocial impact of dental aesthetics among Italian young adults. Acknowledgments The authors thank Dr. Paolo Chiodini and Dr. Carmine Levate´ for their contribution to the research.
References 1. Jenny, J. (1975). A social perspective on need and demand for orthodontic treatment. International Dental Journal, 25(4), 248–256. 2. Mohlin, B., al-Saadi, E., Andrup, L., & Ekblom, K. (2002). Orthodontics in 12-year old children. Demand, treatment motivating factors and treatment decisions. Swedish Dental Journal, 26(2), 89–98.
3. Kiyak, H. A. (2008). Does orthodontic treatment affect patients’ quality of life? Journal of Dental Education, 72(8), 886–894. 4. Bernabe´, E., & Flores-Mir, C. (2006). Normative and self-perceived orthodontic treatment need of a Peruvian university population. Head & Face Medicine, 3(2), 2–22. 5. Bernabe´, E., Kresevic, V. D., Cabrejos, S. C., Flores-Mir, F., & Flores-Mir, C. (2006). Dental esthetic self-perception in young adults with and without previous orthodontic treatment. The Angle Orthodontist, 76(3), 412–416. 6. Gherunpong, S., Tsakos, G., & Sheiham, A. (2006). A sociodental approach to assessing children’s orthodontic needs. European Journal of Orthodontics, 28(4), 393–399. 7. Shaw, W. C., O’Brien, K. D., Richmond, S., & Brook, P. (1991). Quality control in orthodontics: Risk/benefit considerations. British Dental Journal, 170(1), 33–37. 8. Sheiham, A.,& Tsakos, G. (2007) Oral health needs assessment. In Pine C, R Harris (Eds.), Community oral health (pp. 59–79). New Malden, UK: Quintessence. 9. Bowling, A. (1997) Measuring health: A review of quality of life measurement scales (2nd ed). Buckingham, UK: Open University Press. 10. Klages, U., Claus, N., Wehrbein, H., & Zentner, A. (2006). Development of a questionnaire for assessment of the psychosocial impact of dental aesthetics in young adults. European Journal of Orthodontics, 28(2), 103–111. 11. Lin, H., Quan, C., Guo, C., Zhou, C., Wang, Y., & Bao, B. (2013). Translation and validation of the Chinese version of the psychosocial impact of dental aesthetics questionnaire. European Journal of Orthodontics, 35(3), 354–360.
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Qual Life Res 12. Sardenberg, F., Oliveira, A. C., Paiva, S. M., Auad, S. M., & Vale, M. P. (2011). Validity and reliability of the Brazilian version of the psychosocial impact of dental aesthetics questionnaire. European Journal of Orthodontics, 33(3), 270–275. 13. Montiel-Company, J. M., Bellot-Arcı´s, C., & Almerich-Silla, J. M. (2013). Validation of the psychosocial impact of dental aesthetics questionnaire (Pidaq) in Spanish adolescents. Medicina Oral Patologia Oral y Cirugia Bucal, 18(1), 168–173. 14. Spalj, S., Lajnert, V., & Ivankovic, L. (2013). The psychosocial impact of dental aesthetics questionnaire-translation and crosscultural validation in Croatia. Quality of Life Research, 23(4), 1267–1271. 15. Ngom, P. I., Attebi, P., Diouf, J. S., Diop Ba, K., Badiane, A., & Diagne, F. (2013). Translation and cultural adaptation of a French version of the psychosocial impact of dental aesthetics questionnaire: PIDAQ. L’Orthodontie Franc¸aise, 84(4), 319–331.
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16. Brook, P. H., & Shaw, W. C. (1989). The development of an index of orthodontic treatment priority. European Journal of Orthodontics, 11(3), 309–320. 17. Espeland, L. V., & Stenvik, A. (1991). Orthodontically treated young adults: awareness of their own dental arrangement. European Journal of Orthodontics, 13(1), 7–14. 18. Espeland, L. V., & Stenvik, A. (1991). Perception of personal dental appearance in young adults: relationship between occlusion, awareness, and satisfaction. American Journal of Orthodontics and Dentofacial Orthopedics, 100(3), 234–241. 19. De Baets, E., Lambrechts, H., Lemiere, J., Diya, L., & Willems, G. (2012). Impact of self-esteem on the relationship between orthodontic treatment need and oral health-related quality of life in 11- to 16-year-old children. European Journal of Orthodontics, 34(6), 731–737.
BRIEF COMMUNICATION
Cross-cultural adaptation and validation of the Italian Psychosocial Impact of Dental Aesthetics Questionnaire (PIDAQ) Rosaria Bucci • Roberto Rongo • Eugenio Zito • Angela Galeotti • Rosa Valletta • Vincenzo D’Anto`
Accepted: 15 September 2014 Ó Springer International Publishing Switzerland 2014
Abstract Purpose To validate and cross-culturally adapt the Italian version of the Psychological Impact of Dental Aesthetics Questionnaire (PIDAQ) among Italian young adults. Methods After translation, back translation, and crosscultural adaptation of the English PIDAQ, a first version of the Italian questionnaire was pretested. The final Italian PIDAQ was administered to 598 subjects aged 18–30 years, along with two other instruments: the aesthetic component of the index of orthodontic treatment need (IOTN-AC) and the perception of occlusion scale (POS), which identified the self-reporting grade of malocclusion. Structural validity was assessed by means of factorial analysis, internal consistency was measured with Cronbach’s alpha coefficient (a), convergent validity was assessed by means of Spearman correlation, and test–retest reliability was calculated with intra-class correlation coefficient (ICC) and standard measurement error.
Rosaria Bucci and Roberto Rongo have contributed equally to this work. R. Bucci R. Rongo R. Valletta V. D’Anto` (&) Department of Neuroscience, Reproductive Sciences and Oral Sciences, School of Orthodontics, University of Naples ‘‘Federico II’’, Via Pansini 5, 80131 Naples, Italy e-mail: [email protected] E. Zito Department of Translational Medical Sciences, University of Naples ‘‘Federico II’’, Via Pansini 5, 80131 Naples, Italy A. Galeotti V. D’Anto` Division of Dentistry, Department of Pediatric Surgery, ‘‘Bambino Gesu`’’ Children’s Hospital, Viale di San Paolo, 15, 00146 Rome, Italy
Criterion validity was evaluated by multivariate and univariate analysis of variance with Bonferroni post hoc tests. Results The a of the Italian PIDAQ domains ranged between 0.79 and 0.92. The ICC was between 0.81 and 0.90. The mean scores of each PIDAQ domain showed a statistically significant difference when analysed according to the IOTN-AC and POS scores. Conclusion The satisfactory psychometric properties make PIDAQ a usable tool for future studies on oral healthrelated quality of life among Italian young adults. Keywords Quality of life in orthodontics Cross-cultural adaptation Questionnaire validation Young adults Aesthetics
Introduction Even though malocclusion cannot be considered a lifethreatening disease, the self-perception of dental aesthetics plays a crucial role in quality of life (QoL) [1, 2]. The recent increase in demand for orthodontic treatment may be ascribed to the greater attention on the aesthetic and social implications of the dental issues rather than the significant worsening of health status [3–5]. However, the traditional tools adopted by the clinicians to assess orthodontic treatment need are based on ideal concepts of occlusion and aesthetics [6], neglecting the effects of malocclusion on patients’ QoL [7–9]. Hence, it becomes critical to have a tool able to correctly determine patients’ perceptions of malocclusion. The Psychosocial Impact of Dental Aesthetics Questionnaire (PIDAQ) is a specific questionnaire, developed by Klages et al. [10]. It is composed of 23 items, divided into four domains: dental self-confidence (DSC, 6 items),
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social impact (SI, 8 items), psychological impact (PI, 6 items), and aesthetic concern (AC, 3 items). The possible responses for each item are as follows: zero = not at all; one = a little; two = somewhat; three = strongly; and four = very strongly. Differently from the other domains, the items of the DSC show positive meaning and interpretation. The PIDAQ can be used to assess orthodontic treatment need and to evaluate changes in oral health-related quality of life (OHRQoL) due to the orthodontic treatment [10]. Its use is widespread as it has already been translated in several languages [11–15], but not in Italian. Hence, the aim of this study was to translate and cross-culturally adapt the PIDAQ into the Italian language and to validate the questionnaire among Italian young adults, in order to provide a valid instrument for OHRQoL studies. The hypotheses were that the Italian PIDAQ had four different domains, as in the original instrument, each with a Cronbach’s alpha coefficient for the subscales (a) [ 0.79. In addition SI, PI, AC, and the reversed DSC were expected to have a positive correlation (Spearman correlation coefficient r [ 0.4) with two scales, the aesthetic component of the index of orthodontic treatment need (IOTN-AC) [16] and the perception of occlusion scale (POS) [17, 18] used for the self-rating of the malocclusion, as suggested by other authors [10–15].
Subjects and methods Translation Four orthodontic postgraduate students, proficient in English and Italian and familiar with the QoL terminology and instruments, independently translated the PIDAQ from English to Italian. Back translation One English teacher, naı¨ve to the QoL terminology, blinded to the purpose of the study, and with no knowledge of the original English questionnaire, back-translated the Italian version of the PIDAQ into English.
items in the Italian questionnaire, comparing those to the English version. After these phases, the first version of the Italian PIDAQ was created. Pretest The first version of the Italian PIDAQ was pilot tested on a convenience sample of 30 volunteers (17 females and 13 males), aged 18–30 years, recruited from the University of Naples ‘‘Federico II’’, Italy. The pilot test was performed by a single investigator (RB), through a direct interview, to assess possible difficulties in understanding the questionnaire. At the end of this phase, no adjustments were made to the initial version of the Italian PIDAQ. Translated version of PIDAQ The validity and reliability assessment of the Italian PIDAQ were carried out on a convenience sample of 598 young adults aged 18–30 years (296 females mean age 22.6 ± 3.1; 302 males mean age 22.8 ± 3.2) from the Campania area (Italy). The Italian PIDAQ was administered along with two standardized instruments, which aimed to correctly assess the self-reported degree of malocclusion: IOTN-AC and POS. The IOTN-AC is composed of 10 black and white photographs representing different kinds and degrees of malocclusion. The subjects were asked to indicate which photograph best represented their own teeth. The POS is a self-reported scale, composed of six statements based on dental aesthetic features of the frontal teeth. Intellectual and/or physical inability to answer the questionnaire, previous orthodontic treatment, and the presence of cavities, missing or fractured teeth and dark areas on the frontal teeth were considered exclusion criteria since they could influence the self-assessment of the malocclusion. Moreover, dentists and dentistry students were excluded due to their specific knowledge of the field. For the test–retest reliability assessment, 75 subjects were randomly selected to respond to the questionnaire a second time, at least 10 days after the first administration.
Cultural adaptation/committee review
Statistical analysis
A committee of three orthodontists and a psychologist, all fluent in English and familiar with QoL tools, adapted the Italian questionnaire in order to improve the semantic equivalence of meaning between the two English versions. Another committee of two experts in QoL and oral health evaluated the meaning and the importance of the
The Statistical Package for Social Science (SPSS Inc., Windows Release 19.0, Chicago, Illinois, USA) and the Statistical Analysis Software, version 9.3 (SAS Inc., Cary, NC, USA) were used to perform the statistical analysis. To facilitate the interpretation of the results, the scores of the DSC were reversed.
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Validity The structural validity of the PIDAQ was assessed using explanatory and confirmatory factor analysis. The criterion validity was determined by means of multivariate and univariate analysis of variance, with Bonferroni post hoc tests, evaluating the scores of each PIDAQ domain according to IOTN-AC and POS scores. The level of significance was set at P \ 0.05. Convergent validity was assessed by means of the Spearman correlation (r) between PIDAQ and IOTN-AC and POS. Reliability The internal consistency was calculated using the Cronbach’s alpha coefficient (a) for the subscales. A sample of 598 subjects each responding to 3, 6, 8 items, as PIDAQ domains, achieves 100 % power to detect the difference between the null hypothesis of a = 0.7 and the alternative hypothesis of a = 0.79 with P \ 0.05. The reproducibility was assessed as test–retest reliability on a sample of 75 subjects by means of intra-class correlation coefficient (ICC), standard measurement error (SME) and limits of agreement (LOA). A sample of 75 subjects with two observations per subject produces a twosided 95 % confidence interval with a width of 0.16 when ICC = 0.81 and a two-sided 95 % confidence interval with a width of 0.089 when ICC = 0.90, with P \ 0.05.
Results Cross-cultural adaptation During the cross-cultural adaptation, semantic and conceptual equivalence were reached using the same domains of the original questionnaire. Moreover, the pretest analysis demonstrated that young Italian adults could easily understand the questionnaire. Therefore, the cross-cultural adaptation resulted in a tool that was ready to be submitted. Validity The explanatory factor analysis detected four factors, which explained the 67.9 % of the variance reproducing the same division of items for groups of the original PIDAQ. The confirmatory factor analysis proved that the tested model had a high model fit indices (comparative fit index = 0.92, Table 1). According to the IOTN-AC scores, the participants were divided into four groups. The mean scores of each PIDAQ domain showed a statistically significant difference when
compared according to the IOTN-AC scores (Table 2). Similarly, the subjects were divided into four groups according to the POS scores, and the four PIDAQ domains demonstrated statistically significant differences when divided by the POS scores (Table 3). The Spearman coefficient for each domain ranged between 0.49 (SI) and 0.60 (AC) for the IOTN-AC and between 0.48 (DSC) and 0.64 (AC) for the POS (Tables 2, 3). Reliability The internal consistency measured between 0.79 (PI) and 0.92 (AC). Test–retest reliability ranged from 0.81 (AC) to 0.90 (DSC), and the percentage of difference in the LOA range was between 90.7 % (DSC) and 97.3 % (SI, PI) (Table 1).
Discussion The PIDAQ questionnaire is considered a valid instrument to assess the OHRQoL among young adults [10], but it has not yet been translated into the Italian language. During the cross-cultural adaptation, there was no need to apply modifications to the first-structured version of the Italian PIDAQ probably due to a substantial affinity between the European sociocultural contexts where the questionnaires were developed and tested. On the contrary, the Chinese PIDAQ cross-cultural adaption required several drafts before constructing a final version [11]. The factorial analysis of the Italian PIDAQ confirmed a fourdomain structure, similar to the original one. Moreover, the statistical analysis supported the hypotheses of the satisfactory psychometric properties of the questionnaire. The statistically significant results of both univariate and multivariate analysis and the increasing of PIDAQ values together with the increasing of the reported grade of malocclusion (Tables 2, 3) demonstrate the ability of the Italian PIDAQ to discriminate between different levels of self-reported malocclusion. Similar results were found in the original paper [10] when using the POS and the IOTN-AC, and in the Chinese PIDAQ translation [11] in which the authors adopted the same protocol to assess the criterion validity. However, similar results were also found in other PIDAQ validations [12–15] in which an objective assessment of the severity of malocclusion was performed. Regarding reliability, both a and ICC were satisfactory and comparable to those of the original questionnaire [10]. Since the association between self-esteem and the malocclusion effects on the OHRQoL was proved [19], the selfreported level of malocclusion should be integrated with an evaluation of self-esteem and self-concept in future studies.
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4.3 ± 4.9
4.2 ± 3.7
2.6 ± 3.5
Social impacts (8 items)
Psychological impacts (8 items)
Aesthetic impacts (8 items)
0–12
0–17
0–21
0–24
Range
0.92
0.79
0.86
0.90
a
0.86–0.91
0.72–0.79
0.82–0.86
0.88–0.90
a if item deleted
0.79–0.88
0.34–0.69
0.49–0.79
0.66–0.81
Range of interitem correlation
0
0
0
0
MI (%)
0.81(0.72–0.88)
0.84(0.76–0.90)
0.88(0.82–0.93)
0.90(0.84–0.93)
ICC (95 %CI)
1.52
1.48
2.07
1.70
SME
4.23
4.10
5.76
4.73
SDC
Test–retest reliability (N = 75)
0.07
-0.11
-0.70
-0.15
Paired difference mean
-0.13–0.26
-0.45–0.24
-0.32–0.18
-0.58–0.29
95 %CI
0.63
0.38
0.6
0.78
P
0
0
0
0
MI (%)
-1.61–1.75(95 %)
-3.03–2.82(97 %)
-2.19–2.05(97 %)
-3.48–3.54(91 %)
LOA
1
Scores have been reversed
P statistical significance of the paired t test for each domain Confirmatory factor analysis: CFI comparative fit index = 0.92, RMSR root mean square residual = 0.07, SRMSR standardized RMSR = 0.07, RMSEA root mean square error of approximation = 0.10
pffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffi a Cronbach’s alpha, MI percentage of missing items, ICC intra-class correlation, SME standard measurement error was calculated as SD ð1 ICCÞ, SDC smallest detectable change was calculated as 1.96 MEH2
LOA Limits of agreement were calculated as paired difference mean ± 1.96 standard deviation (percentage within LOA)
11.6 ± 5.4
Mean ± SD
Internal consistency (N = 598)
Dental selfconfidence (6 items)
Domain1
Table 1 Internal consistency (N = 598) and test–retest reliability (N = 75) for the PIDAQ domains
Qual Life Res
Qual Life Res Table 2 Results of multivariate and univariate analysis of variance of the PIDAQ scores according to the different IOTN-AC scores, and Spearman coefficient of correlation between the PIDAQ domains and IOTN-AC IOTN-AC
Scores of PIDAQ (mean ± SD)
Score
Dental self-confidence ,
***
Social impact***
Psychological impact***
Aesthetic concern***
1 (n = 199)
9.1 ± 4.4a
1.9 ± 2.9a
2.5 ± 2.6a
0.7 ± 1.4a
2 (n = 169)
a
b
b
1.2 ± 1.6a
c
9.7 ± 4.6
3.4 ± 3.9
3.5 ± 2.7
3 (n = 121) C4 (n = 109)
12.8 ± 4.0 17.6 ± 4.7c
4.9 ± 4.1 9.4 ± 6.2d
4.7 ± 3.0 8.1 ± 4.6d
3.7 ± 3.2b 7.0 ± 4.2c
Spearman correlation
r = 0.53***
r = 0.49***
r = 0.51***
r = 0.60***
a,b,c,d
b
c
Bonferroni post hoc test, different letters intra-domain indicate statistically significant differences among scores
*** P \ 0.001
Scores have been reversed
Table 3 Results of multivariate and univariate analysis of variance of the PIDAQ scores according to the different POS scores, and Spearman coefficient of correlation between the PIDAQ domains and POS POS
Scores of PIDAQ (mean ± SD)
score
Dental self-confidence , *** a
Social impact*** 1.6 ± 2.4
a
Psychological impact*** 2.3 ± 2.4
Aesthetic concern***
a
0.6 ± 1.2a
0–1 (n = 205)
9.3 ± 4.2
2–4 (n = 213)
10.1 ± 4.9a
3.8 ± 4.0b
3.7 ± 2.7b
1.4 ± 1.8b
5–8 (n = 114)
13.9 ± 3.5
b
5.5 ± 3.5
c
5.0 ± 2.9
c
4.9 ± 3.1c
C9 (n = 66)
19.5 ± 4.3
c
12.4 ± 6.1
d
10.7 ± 4.0
d
8.6 ± 4.2d
Spearman’s correlation
r = 0.48***
a,b,c,d
r = 0.53***
r = 0.56***
r = 0.64***
Bonferroni post hoc test, different letters intra-domain indicate statistically significant differences among scores
*** P \ 0.001
Scores have been reversed
One limitation of this study was the lack of investigation about the responsiveness of the Italian PIDAQ.
Conclusion The Italian PIDAQ showed satisfactory validity and reliability. Therefore, its good psychometric properties make it a suitable tool for the assessment of psychosocial impact of dental aesthetics among Italian young adults. Acknowledgments The authors thank Dr. Paolo Chiodini and Dr. Carmine Levate´ for their contribution to the research.
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