[Epidemiological characteristics and changes of malnutrition among students aged 6-14 in Beijing in 2015 and 2019]

To analyze epidemiological characteristics and temporal changes in the prevalence of thinness, anemia, overweight and obesity among primary and secondary school students in Beijing between 2015 and 2019.

The survey participants were students who participated in the Beijing Primary and Secondary School Students' Nutrition and Health Status Monitoring in 2015 and 2019. A multistage stratified cluster random sampling method was employed to select 14, 126 students in grades 1, 3, 5, and 7 from 56 schools across 7 districts of Beijing for height, weight, and hemoglobin measurements, with classifications of thinness, anemia, overweight, and obesity determined using diagnostic thresholds from Chinese health industry standards Growth Standard for Children Under 7 Years (WS/T 423-2022), Screening Standard for Malnutrition of School-age Children and Adolescents (WS/T 456-2014), Screening Standard for Overweight and Obesity among School-age Children and Adolescents (WS/T 586-2018), and Method for Anemia Screening in Population (WS/T 441-2013); malnutrition prevalence among demographic subgroups was described using constituent ratios with between-year (2015 vs.2019) differences compared by χ2 test, while generalized linear mixed models analyzed changes in malnutrition prevalence adjusted for age, sex, and residential area.

The survey revealed that among Beijing students aged 6-14 years, the overall thinness prevalence increased from 378 cases (5.25%) in 2015 to 435 cases (6.28%) in 2019, with statistically significant increases observed among girls (171 (4.88%) vs.208 (6.08%)), suburban students (197 (4.41%) vs.271 (6.20%)), and the 6-9 age group (181 (5.09%) vs.242 (6.81%)) (P<0.05); simultaneously, the overall anemia detection rate decreased from 197 (2.74%) in 2015 to 131 (1.89%) in 2019, with significant declines among boys (97 (2.63%) vs.58 (1.65%)), suburban students (166 (3.72%) vs.110 (2.52%)), and the 6-9 age group (161 (4.52%) vs.79 (2.22%)), while conversely increasing in the 10-14 age group (36 (0.99%) vs.52 (1.54%)) (all P<0.05); both overweight prevalence (1137 (15.80%) in 2015 vs.1106 (15.96%) in 2019) and obesity prevalence (1410 (19.60%) in 2015 vs.1367 (19.72%) in 2019) showed no statistically significant differences overall or within any demographic subgroups; generalized linear mixed model analysis confirmed increased thinness risk in 2019 (OR=1.21, 95% CI 1.05-1.40), decreased anemia risk (OR=0.67, 95% CI 0.53-0.83), and non-significant changes in overweight/obesity prevalence between survey years.

The thinness prevalence among Beijing students aged 6-14 years in 2019 had increased compared to 2015 levels, while anemia rates have shown a declining trend during the same period, the prevalence of overweight and obesity remained relatively stable overall. These indicators displayed multidimensional differentiation patterns across gender, region, and age.