Decomposing Socioeconomic Inequality in Early Childhood Caries Among 3 to 5-Year-Old Children in China

Early childhood caries (ECC) is a widespread oral disease that harms children's health in China. Although previous studies have linked ECC prevalence to socioeconomic status, few have measured the degree of socioeconomic inequality. This study aimed to evaluate the socioeconomic inequality of ECC in children aged 3 to 5 years in China and identify the contributor to the inequality. We extracted data on 3 to 5-year-old children from the fourth National Oral Health Survey. We measured the inequality of ECC by the average household income per capita. We used the average household income per capita to measure the inequality of ECC. To describe inequality both qualitatively and quantitatively, we used the following methods: concentration curve, Erreygers-corrected concentration index, relative index of inequality and slope index of inequality. We also applied a decomposition based on the probit model to identify the factors that contributed to inequality. The prevalence of ECC in Chinese preschool children was 63.11% (95% CIs: 60.54%, 65.61%). The negative value of the Erreygers-corrected concentration index (−0.0459; 95% CIs: −0.0594, −0.0324), slope index of inequality (−0.0674; 95% CIs: −0.0876, −0.0471) and the positive value of relative index of inequality (0.7484; 95% CIs: 0.6856, 0.8169) all indicated that ECC prevalence was higher among children from low-income families. The main factors contributing to inequality were average household income, parents' educational level and living areas. There is a pro-poor inequality in ECC among 3 to 5-year-old children in China. To improve oral health equality, policymakers should focus more on children from low-income families, with less educated parents and living in rural areas.