This study is the first attempt to deploy a valid cross-cultural instrument used effectively in many countries worldwide to measure the oral health–related quality of life (OHRQoL) of preschool children in Thailand. ECOHIS focuses on the impact of ECC, which has been a major health problem in Thai preschoolers. The most recent National Oral Health Survey in Thailand in 2017 revealed that the prevalence of ECC was 52.9% in 3-year-olds and 75.6% in 5-year-olds [24]. An assessment of the impact of these oral health problems on children’s quality of life has never been conducted. The ECOHIS has been adapted for use in some Asian populations with a similar ECC situation as in Thailand [14–16, 18, 22]. The Thai version of ECOHIS was developed from the original version following the standard cross-cultural adaption process [26]. All 13 items of the original ECOHIS were retained, and thus the Th-ECOHIS could be employed in cross-national comparisons. However, some revisions were made to be more applicable when used in Thai context.
The original version of the ECOHIS was developed as a self-completed questionnaire by proxy [8]. Although the Th-ECOHIS kept the original context, it was interviewer-administered. The interview approach was considered suitable for the studied population because it is a personal approach, ensures full return rates, lessens the possibility of missing data, and is nonliteracy dependent. Although the literacy rate of working-age adults in Thailand is about 82%, the literacy rates of females and older persons are lower, at 78% and 52%, respectively [27]. One third of Thai adults aged 25 to 50 years are not fond of reading [27]. This was confirmed during the face validation process, when the mode of administration was also discussed; the participants preferred the interviewing mode because they felt it would help them focus on the questions and process better. The Brazilian version of ECOHIS had similar levels of reliability and validity and psychometric findings regarding self-administration and interviewer-administration [23]. A number of studies using other OHRQoL instruments demonstrated that the mode of administration does not affect the performance of the measure [28, 29].
Most of the caregivers who participated in this study were able to rate their children’s and family’s experience as asked in the Th- ECOHIS. The fact that there were only four responses of Don’t Know (1%) shows that few of the caregivers had likely underestimated the effects of ECC. There were no blank responses in our study because with the interview-administration mode, respondents answered each question. Approximately one half of caregivers reported at least one impact related to oral health affecting their children and families (Th-ECOHIS score > 0). The ceiling Th-ECOHIS score of each section was not detected, and this was consistent with other validation studies [8, 14, 15, 17, 22]. Regarding the floor effect, our study showed a higher rate in the child impact section than the original study, indicating that the percentage of affected children in this study was lower than in the previous study [8]. The participants recruited in this study were limited to 3-year-olds, whereas the original study included samples of 5-year-olds [8]. The younger age group could have been less affected by ECC, with a lower level of severity, and might also have presented with fewer symptoms and less impairment than the older age group. However, the three most common problems reported in the child impact section, pain, irritation and frustration, and eating difficulty, were similar to those reported in the original version [8] and other countries with different cultures [15, 19, 23]. Apparently, a child’s physical complaints and limited routine functioning were more easily detected by parents than a child’s psychological and social effects. In the family impact section, as in some other studies [8, 15, 19, 23], the most frequent feelings of caregivers were guilt and being upset. Although dental insurance is not available in Thailand, most simple dental services are provided free of charge for children younger than 12 years; only 10% of caregivers reported experiencing a financial impact on their family.
The reliability assessment of the Th-ECOHIS demonstrated an excellent result similar to the original version and previous studies. The test–retest analysis was conducted over a period of 2 weeks revealed good agreement (0.87), indicating that the Th-ECOHIS questionnaire was able to yield stability scores when administered at two different times. The ICC value was similar to that reported in the original English, German, and Farsi versions of the ECOHIS (0.84, 0.81, and 0.82, respectively) [8, 12, 14].
Regarding the consistency of results across items within questionnaire, the overall Cronbach's alpha value was 0.85, demonstrating good internal reliability of Th-ECOHIS. This value was slightly lower than that reported in the original English [8] and German versions [12] but was within the same range reported in the Arabic, Brazilian, Lithuanian, and Malay versions [14, 15, 17, 23]. Comparing the internal consistency of the child impact section and the family impact section, the Cronbach’s alpha coefficient in the family impact Sect. (0.71) was lower than that in the child impact Sect. (0.84). This was similar to previous studies in which the internal consistency in the child impact section and the family impact section ranged from 0.74 to 0.92 and 0.59 to 0.85, respectively. The smaller number of items in the family impact section in Th-ECOHIS might have been one of the factors influencing this lower consistency.
To assess the Th-ECOHIS validity, convergent and discriminant analyses were conducted. The analyses showed that the Th-ECOHIS had good validity in both tests. Regarding the convergent validity, our study used the global measure of oral health to assess the validity of the Th-ECOHIS. This measure is commonly used as a subjective indicator and has been demonstrated to be highly correlated with the clinical oral health status 30]. The Th-ECOHIS showed a moderate correlation with the global measure of oral health. The correlation of our finding was higher than in the original version [8] and was comparable with the Turkish and Brazilian versions [22, 23]. This finding showed that parents who perceived their children as having poor oral health tended to have a higher ECOHIS score.
In the discriminant validity test analysis, our study compared the Th-ECOHIS scores among children who were caries-free, had ECC (dmft 1 to 3), and had severe ECC (dmft 4 or higher). The results support the discrimination ability of the Th-ECOHIS among caries free and caries affected children with different severity. The Th-ECOHIS score could be a valid indicator for quality of life measurement. This also implied that parents are reliable for assessment of their child’s quality of life based on the child’s oral health. It should be noted that the ECOHIS scores were reported for the child and family impact sections even in caries-free children. This reflects that oral problems that can affect a child’s quality of life are not limited to dental caries.
The original ECOHIS aimed to assess the impact of both oral health problems and related treatment experiences on the quality of life of preschool children and their families [8]. Most studies using a translated form of ECOHIS focused on a mixed-age group of preschoolers and the original focused only on 5-year-olds [8]. However, our study included only 3-year-olds, which this group evidently had a consistently high prevalence of ECC, for psychometric analysis [24, 25]. The caries prevalence of Bangkok metropolitan children, according to the most recent national survey, is 49.5% in 3-year-olds and increases to 66.1% in 5-year-olds, a percentage slightly lower than overall in Thailand. Because a full response from caregivers could be achieved with the design of the interview-administered questionnaire, the age group of the children might not have affected the validity and reliability of the study. However, it might affect the magnitude of the impact of oral health problems, which was not an objective of our study. The ECOHIS was proved valid for this particular age group. Nevertheless, further studies of different age groups would help strengthen our results. Although some studies demonstrated that the mode of administration does not affect the measuring performance [23, 28, 29], self-administration has more advantages in terms of lower cost, the preservation of participants’ anonymity and autonomy, avoidance of interviewer bias, and availability for a large number of samples. The Th-ECOHIS questionnaire in self-completed mode should be tested in future studies.