This study aimed to validate a Mexican version of the ECOHIS questionnaire in a sample of Mexican children and their caregivers. As a main result, M-ECOHIS demonstrated validity in relation to consistency, reproducibility, convergent, and discriminant validity, in accordance with our hypothesis. Although ECOHIS has been validated in several countries, the Mexican population still needed validation of instruments to assess OHRQoL in preschoolers.
Approximately half of the children had untreated dental caries, which may influence that "pain in the teeth, mouth or jaw" was the impact most frequently reported in the child section. Previous studies indicate that children with untreated dental caries may have difficulty eating, sleeping and socializing, in addition to affecting your self-confidence, weight and growth, causing a negative impact on your quality of life [22–24]. Considering the family section, the item "they affected the economy in your family/home" was the most frequent impact reported, which could suggest that oral health often affects children's quality of life and their family's finances. These findings were according to previous studies [12, 15], which indicate that M-ECOHIS can be compared with other versions of ECOHIS performed in different countries and cultures.
Test-retest reliability (reproducibility) was adequate, with an ICC of 0.95, similar to the value reported in Peru [12], Brazil [25] and Turkey [26] and higher than the values reported in the United States of America [13] China [27] and Persia [22]. In this context, the Mexican version of ECOHIS showed excellent reproducibility, as it is capable of producing consistent results when administered at two different times to the same person [28]. Regarding internal consistency, Cronbach's alpha was 0.80 for the children's section, 0.78 for the family section, and 0.85 for the general M-ECOHIS, which indicates a good internal consistency that values 0.7021. Other ECOHIS validation studies have reported similar values [14.22,25,27]. In addition, all M-ECOHIS items confirm the latent variables in the impact of the child and family section, also confirming the construction validity, as recommended in the previous literature [21].
In addition, our findings demonstrated that children with caries experience and with untreated caries had significantly higher overall scores on the M-ECOHIS, demonstrating the questionnaire's discriminating ability. Similar results have been observed in other versions [12, 24, 26, 27]. As described, individuals with dental caries are more likely to have dental pain, difficulties sleeping and eating, which can directly impact a worse OHRQoL [29]. Notwithstanding, significant impacts were also observed in the child's section according to the presence of traumatic dental injuries, according to previous studies [30].
The present study was carried out in a sample of children from 3 to 5 years old, although this instrument has been developed and validated for use in children from 0 to 5 years old13, which can limit our findings. However, it is more difficult to obtain cooperation from children under 3 years of age, and only a minority in this age group attend nursery schools. In relation to the strengths, the application of this instrument in preschool children can make it possible to evaluate the effectiveness of oral health programs, in addition to prioritizing investments, evaluating treatment results, and comparing children's oral health throughout childhood [15]. Future studies are recommended, especially in Mexican populations, where instruments related to the quality of life have recently been validated.