Association between convenience stores near schools and obesity among school-aged children in Beijing, China

Background Food environments have rapidly changed over the past years in China and children have more access to unhealthy food in convenience stores near schools. Since the studies on the association between convenience stores near schools and obesity had inconsistent results and no similar study in China, we conducted a study on the association in Beijing of China, which will provide scientific evidence for the intervention of childhood obesity. Methods The study included 2201 students at grade 4 of 37 primary schools in Dongcheng or Miyun district of Beijing. The food environment data was acquired from AMAP, the free web-based geospatial service provider. The numbers of convenience stores were captured within the 800-m network buffer near schools using Geographic Information System. The weight and height of each student were measured by trained health professionals. Students' dietary and physical behaviors and other information associated with obesity were collected with questionnaires for students and their parents. The generalized linear mixed model (GLMM) was used to analyze the data. Results The average age of the students was 10.2 years (Standard Deviation (SD) = 0.33). The prevalence of obesity in students was 14.9%. The median number of convenience stores within the 800-m network buffer near schools was 24 in two districts. The number of convenience stores near each school varied from 5 to 67 (median: 25) in Dongcheng district and from 1 to 57 (median: 22) in Miyun district. After adjusting for the confounding factors at the family and individual levels, the association between convenience stores and childhood obesity was statistically significant. Additional ten convenience stores near schools were associated with an increased risk of obesity (Odds Ratio (OR) = 1.13, 95% confidence interval (CI): 1.03,1.24, P = 0.011). Compared with less than 24 convenience stores near schools, the students with more than or equal to 24 convenience stores near schools had an increased risk of obesity (OR = 1.49, 95% CI: 1.09, 2.03, P = 0.013). Conclusion The students with more convenience stores near their schools had an increased risk of obesity. The findings provided evidence for developing public health policy to restrict the number of convenience stores near schools to prevent and control childhood obesity.