Socioeconomic inequality in different phenotypes of childhood obesity and its determinants in Iran: a Blinder-Oaxaca decomposition method

Background Childhood obesity has become a significant public health issue worldwide. Socioeconomic status is among its key determinants. This study examined the socioeconomic inequality in different phenotypes of childhood obesity at the national level in Iran. Methods This national, multistage school cross-sectional study was undertaken in 2015 on 14,400 students aged 7–18 years from urban and rural areas of 30 provinces of Iran. Using principal component analysis, socioeconomic status (SES) was categorized into tertiles. SES inequality in different phenotypes of obesity (i.e., generalized obesity", "abdominal obesity", and combined obesity) was estimated using the concentration index. The determinants of this inequality were assessed by the Blinder-Oaxaca decomposition method. Results Overall, 14,274 students completed the study (response rate: 99%). The mean age was 12.28 years, 50.6% were boys, and 71.42% lived in urban areas. The prevalence of generalized obesity and abdominal obesity was 20.8% and 11.3%, respectively. The concentration index for different phenotypes of obesity was positive, indicating that inequality is more common amongst the low SES groups. High SES, being male, living in a rural, and having a positive family history of obesity were associated with general obesity. Moderate physical activity and living in a rural area were associated with abdominal obesity. In addition, living in a rural area, having a high SES, being male, and having a positive family history of obesity were associated with combined obesity. Conclusion According to the present study findings, all childhood obesity phenotypes were more prevalent in Iranian children with high SES. Therefore, due to obesity and other diseases, it is essential to implement environmental changes in addition to designing macro-educational programs and prevention strategies.