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Validation of the Child Perceptions Questionnaire (CPQ11-14)
1 Department of Oral Sciences, School of Dentistry, University of Otago, PO Box 647, Dunedin, New Zealand; and Correspondence: * corresponding author, mthomson{at}gandalf.otago.ac.nz
While the use of adult oral-health-related quality-of-life (OHRQoL) measures in supplementing clinical indicators has increased, that for children has lagged behind, because of the difficulties of developing and validating such measures for children. This study examined the construct validity of the Child Perceptions Questionnaire (CPQ11-14) in a random sample of 12- and 13-year-old New Zealanders. It was hypothesized that children with more severe malocclusions or greater caries experience would have higher overall (and subscale domain) CPQ11-14 scores. Children (N = 430) completed the CPQ11-14 and were examined for malocclusion (Dental Aesthetic Index) and dental caries. There was a distinct gradient in mean CPQ11-14 scores by malocclusion severity, but there were differences across the four subscales. Children in the worst 25% of the DMFS distribution had higher CPQ11-14 scores overall and for each of the 4 subscales. The construct validity of the CPQ11-14 appears to be acceptable.
Key Words: child • oral health • quality of life • validity • malocclusion • dental caries
The last decade has seen increasing recognition of the value of measures of oral-health-related quality of life (OHRQoL) in supplementing clinical indicators. While several measures have been developed and validated for use among adults (Cushing et al., 1986; Atchison and Dolan, 1990; Locker and Miller, 1994; Slade and Spencer, 1994; Leão and Sheiham, 1996), work in the field of child OHRQoL has lagged behind. However, Jokovic et al.(2002) recently reported on the Child Perceptions Questionnaire (CPQ11-14), designed to measure OHRQoL among children aged between 11 and 14 years. The CPQ11-14 includes the four domain subscales of oral symptoms (6 items; e.g., pain), functional limitations (9 items; e.g., difficulty eating), emotional well-being (8 items; e.g., avoiding smiling or laughing around other children), and social well-being (12 items; e.g., being asked questions by other children about his/her mouth). To date, the validity and reliability of the CPQ11-14 have been examined in a clinical convenience sample of 123 children recruited from among pediatric dentistry, orthodontic, and craniofacial patients in Toronto. These groups were chosen since they had distinct clinical characteristics that were expected to have differential effects on the children’s quality of life, thus maximizing variation for validity testing. The discriminative properties (i.e., cross-sectional validity and test-retest reliability) of the CPQ11-14 were found to be acceptable. However, there have been no reports from other populations or settings, and questions remain about the performance of the CPQ11-14 in child populations which exhibit the full distribution of clinical presentations. It is important that the discriminative properties of such measures be acceptable in these populations. Their ability to distinguish between individuals (or groups) with poor OHRQoL and those with better OHRQoL is a key characteristic which would enable such instruments to contribute to improvements in oral health, through identifying those clinical or public health interventions which produce the greatest improvement in OHRQoL. The aim of this study was to examine the construct validity of the CPQ11-14 in a probability-based population sample of 12- and 13-year-old New Zealanders. It was hypothesized that children with more severe malocclusions would have higher overall (and domain) CPQ11-14 scores, and that this would also apply to those with greater dental caries experience.
Ethical approval was obtained from the Taranaki Ethics Committee. In 2003, there were approximately 1600 12- to 13-year-olds enrolled in the Taranaki District Health Board’s (TDHB) school dental service, of whom 961 attended four large intermediate schools. A simple random sample of children in their 8th year of schooling, and who were enrolled with the TDHB school dental service (SDS), was selected from the four intermediate schools and invited to participate. Assuming the prevalence of malocclusion to be 30% in that age group, it was decided that, for a power of 0.8 and a significance level of 0.05, a sample size of 325 was needed. Assuming a 60% response rate, a sample size of 542 was required, and this was rounded up to 600. Parents/caregivers of the sampled children were mailed consent documentation and a questionnaire which sought information on whether the child had received any orthodontic advice and/or treatment, and which included the Parental-Caregiver Perceptions Questionnaire that had been developed, along with the CPQ11-14 (www.cdhsru-uoft.ca/cohqol; Jokovic et al., 2002). We obtained consent from both parent and child before proceeding. Each child completed the CPQ11-14 in the dental clinic waiting room just prior to the dental examination; questions asked about the frequency of events during the previous three months. Response options and scores were: ‘Never’ (scoring 0); ‘Once or twice’ (1); ‘Sometimes’ (2); ‘Often’ (3); and ‘Every day or almost every day’ (4). An overall CPQ11-14 score was computed by addition of all of the item scores, and scores for each of the four domains were also computed. The test-retest reliability of the CPQ11-14 was not examined. The clinical examinations (by LFP) took place in dental clinics at the children’s schools. A standardized sequence was used, with a standard dental caries examination (World Health Organization, 1997) preceding an assessment for malocclusion. Teeth were not cleaned and were examined wet. The orthodontic assessment was carried out based on the Dental Aesthetic Index (Cons et al., 1986), which assesses the relative social acceptability of dental appearance by collecting and weighting data on 10 intra-oral measurements. This enables each individual to be placed on a dental appearance continuum ranging from 13 (the most socially acceptable) to 100 (the least acceptable), and orthodontic treatment need can be prioritized based on the pre-defined categories of ‘minor/none’ (scores 13 to 25), ‘definite’ (26 to 31), ‘severe’ (32 to 35), or ‘handicapping’ (36 or more; Estioko et al., 1994). Where a child presented with a mixed dentition, he/she was asked directly about the reason for any missing teeth, since these are allocated the highest DAI weight. Prior to data capture, the dental examiner underwent a calibration session with an experienced dental epidemiologist (WMT), resulting in inter-examiner intraclass correlation coefficients (ICC) of 0.98 for the DAI score, and 0.93 for DMFS. We investigated intra-examiner reliability by conducting replicate examinations on 19 individuals; an ICC of 0.94 was obtained for the DAI score, and 0.94 for DMFS. Clinical data were entered into a laptop computer by a research assistant. The resulting data were analyzed with the use of SPSS version 10.1 (SPSS Inc., Chicago, IL, USA). Descriptive statistics were followed by bivariate analyses, which used (where appropriate) Chi-square tests for comparison of proportions, and Mann-Whitney or Kruskal-Wallis tests (as appropriate) for comparison of the means of continuous variables. The alpha value was set at P < 0.05.
A simple random sample of 600 was selected with the use of SPSS. Due to a clerical error, one child had been entered twice on a school roll and was sampled twice; this meant that the final random sample was effectively reduced to 599. Some 19 households could not be contacted by mail, and those questionnaires were returned to the examiner. This resulted in an effective sample of 580. The two mail-outs yielded a total of 435 children with parent/caregiver consent to be examined. Five children were unable to be examined, due to three having changed schools during the examination period, one child being absent on each of three visits to the school, and one autistic child being unable to complete his questionnaire. Based on the effective sample, the study participation rate was 74.1% (Locker, 2000).
Males slightly outnumbered females, and one in five participants was Mäori (Table 1
Scores on the CPQ11-14 ranged from 0 to 103 (Table 2  ), and were positively skewed, as were the domain scores (requiring the use of non-parametric tests of statistical significance).
While there was an apparent sex difference in overall CPQ11-14 score (Table 3 ), it did not quite reach statistical significance (P = 0.06); however, the mean emotional well-being domain score for females was higher than that for males. Children in the top quartile of the DMFS distribution had higher CPQ11-14 scores overall, as well as higher scores for each of the four domains. There was a distinct gradient in mean CPQ11-14 scores across the categories of malocclusion severity, whereby those in the ‘Handicapping’ category had the highest and those in the ‘Minor/none’ category had the lowest CPQ11-14 score, on average. Such a gradient was also observed with respect to the emotional well-being and social well-being domain scores, but not with the other two domains.
This cross-sectional study of the construct validity of the CPQ11-14 in a population-based sample of 12- to 13-year-olds has found that it appears to be acceptable, showing higher overall scores among children with more severe malocclusions or with greater dental caries experience. In any study which claims to have generalizable findings, the sample representativeness should be closely examined. Comparison of the sample’s characteristics with the Taranaki child population with the use of three markers (Census estimates for gender and the Mäori population, and school dental service caries data) suggested that the sample was indeed representative. This study set out to examine the construct validity of the CPQ11-14. It was hypothesized that children with more severe malocclusion would have higher scores. This was certainly the case with the overall CPQ11-14 scores, with a clear ascending gradient demonstrated across ascending categories of orthodontic treatment need. However, the domain scores showed some noteworthy differences, with no clear, statistically significant gradient observed for oral symptoms or functional limitations; the emotional and social well-being domain scores did show clear gradients, though. Concerning dental caries experience, there were distinct differences in both the overall and the domain scores between those who were in the highest quartile for DMFS and the remainder. These findings are not counter-intuitive: Other factors being equal, children in the most severe disease quartile are likely (for example) to have experienced more oral pain, had difficulties in chewing, to have worried or been upset about their mouths, or to have missed school due to their cumulative disease experience. However, malocclusion is as much a social phenomenon as an anatomical one, and the DAI was designed specifically to assess the relative social acceptability of dental appearance based upon public perceptions of dental aesthetics. Thus, it is not surprising that clear gradients were observed (across the ascending DAI treatment-need categories) for two of the domains, since ‘being teased’ or ‘avoiding smiling or laughing’ (social well-being) and ‘being upset’ or ‘worrying about being different’ (emotional well-being) are known to be associated with malocclusion, and are important motivating factors in the uptake of orthodontic treatment (Plunkett, 1997). That no clear gradients were observed with the oral symptoms or functional limitations domains is also unsurprising, perhaps, since only the most severe malocclusion might be expected to produce effects in those domains. Validation of measures such as the CPQ11-14 at the population level is important, since clinical samples may give a misleading picture of their utility, because of the biased nature of the sample (Locker, 2000). Further research should (a) examine the validity of the CPQ11-14 in other populations and settings, and (b) investigate its evaluative properties to determine its usefulness as a clinical outcome measure in dental health services research.
We thank the NZ Dental Association Research Foundation and Taranaki District Health Board for their support. Received for publication September 13, 2004. Revision received March 15, 2005. Accepted for publication April 22, 2005.
Journal of Dental Research, Vol. 84, No. 7,
649-652 (2005) This article has been cited by other articles:
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