Abstract: Objective To analyze the trajectory changes of body mass index(BMI) and its association with further overweight and obesity among non-overweight and non-obesity primary and secondary school students at baseline, in order to provide basis for controlling the incidence of overweight and obesity among children and adolescents in China. Methods The physical examination data of primary and secondary school students were collected from a cohort study designed in Longkou City from 2015 to 2022, and 7 346 non-overweight and non-obesity students at baseline were included in thus study. The Generalized linear model was used to analyze the effect of baseline BMI level on further BMI level after 8 years of follow-up, and stratified analysis was performed according to age groups. Linear trend test was used to analyze the influence of baseline BMI level on end-stage BMI change trend. Results During the follow-up period, the detection rates of overweight and obesity were 14.6%, 17.9%, 17.7%, 17.7%, 18.3%, 20.4%, and 18.3% from 2016 to 2022, respectively. Among these, the detection rate of overweight and obesity in 2021 was highest. At different baseline ages, changes with follow-up years followed the same pattern, with overweight and obesity rate trend firstly up and then down with age, with the rate of increase peaking at around 10 years old. After 8 years of follow-up, compared with the baseline, the further new-onset overweight and obesity rate was 18.3%, and boys(21.5%) were higher than girls(15.8%). Compared with the baseline BMI-Z level＜-2, the correlation of primary BMI-Z with final BMI-Z level was stronger (P_trend <0.001) in baseline BMI-Z＞-1 group (β=1.191, 95%CI:0.853 - 1.529). When baseline BMI level was 1 - 2, it had a greater impact on the final BMI level for students agded 9 - 11 than students agde 6 - 8 (β=1.600, 95%CI:1.360 - 1.839). Conclusions The new-onset overweight and obesity rate of boys in Longkou City was higher than girls. The incidence of overweight and obesity in the age group of 9 - 11 years increases rapidly, and it was closely correlated with the level of further BMI. Comprehensive prevention and control strategies should be implemented to focus on prevention and control, and to reduce the risk of overweight and obesity effectively.

Key words: body mass index, overweight and obesity, changing trend

摘要： 目的 分析基线非超重肥胖中小学生体质量指数(BMI)轨迹变化,及其与终期超重肥胖的关联,为控制我国儿童青少年超重肥胖发生率提供依据。方法 本研究基于队列研究设计,采用龙口市2015—2022年连续随访8年中小学生体检数据,纳入基线非超重肥胖学生7 346人进行分析。采用广义线性模型,分析基线BMI水平对随访8年后终期BMI水平的影响,并按照年龄段进行分层分析;采用线性趋势检验计算基线BMI水平对终期BMI水平变化趋势的影响。结果 随访期间,2016—2022年超重肥胖人数率分别为14.6%、17.9%、17.7%、17.7%、18.3%、20.4%和18.3%,其中2021年学生超重肥胖率最高;在不同基线年龄,随着随访年度的变化都遵循了相同的规律,随着年龄的增长,超重肥胖率呈先上升再下降的趋势,增速高峰在10岁左右;随访8年后,与基线相比,终期新发超重肥胖率为18.3%,其中男童新发超重肥胖率为21.5%,女童为15.8%,男童高于女童;与基线BMI水平低于-2相比,水平高于-1组时,与终期BMI水平的关联性更强(P_趋势＜0.001),相对于6~8岁学生(β＝1.191,95%CI :0.853～1.529),基线BMI水平在1～2时,对9~11岁学生(β＝1.600,95%CI:1.360～1.839)终期BMI水平的影响均更大。结论 龙口市男童的新发超重肥胖率大于女童;9～11岁超重肥胖发生率增加较快,且与终期BMI水平相关性较强,应实施综合防控策略,对这部分人群进行重点防控,有效降低超重肥胖发生风险。

关键词: 体质量指数水平, 超重肥胖, 变化趋势