The Influence of Secular Trends in Body Height and Weight on the Prevalence of Overweight and Obesity among Chinese Children and Adolescents

Objective To explore the influence of secular trends in body height and weight on the prevalence of overweight and obesity among Chinese children and adolescents. Methods The data were obtained from five cross-sectional Chinese National Surveys on Students’ Constitution and Health. Overweight/obesity was defined as BMI-for-age Z-score of per the Wold Health Organization (WHO) reference values. Body height and weight for each sex and age were standardized to those reported in 1985 (standardized height: SHY; standardized weight: SWY) and for each sex and year at age 7 (standardized height: SHA; standardized weight: SWA) using the Z-score method. Results The prevalence of overweight/obesity in Chinese children was 20.2% among boys and 10.7%among girls in 2010 and increased continuously from 1985 to 2010. Among boys and girls of normal weight, SHY and SHA were significantly greater than SWY and SWA, respectively (P < 0.001). Among boys and girls with overweight/obesity, SHY was significantly lower than SWY (P < 0.001), and showed an obvious decreasing trend after age 12. SHA was lower than SWA among overweight boys aged 7-8 years and girls aged 7-9 years. SHY/SHW and SHA/SWA among normal-weight groups were greater than among overweight and obese groups (P < 0.001). Conclusion The continuous increase in the prevalence of overweight/obesity among Chinese children may be related to a rapid increase in body weight before age 9 and lack of secular increase in body height after age 12.     

Report on Childhood Obesity in China （5） Body Weight, Body Dissatisfaction, and Depression Symptoms of Chinese Children Aged 9-10 Years

Objective To investigate the relationship between body weight, body dissatisfaction and depression symptoms among Chinese children. Methods The fasting body weight and height of the third and fourth grade students (n=3886, aged 9 or 10 years) from 20 schools in Beijing, China, were measured, and the students were asked to choose the figures of body image and to complete the self-reported children’s depression inventory (CDI) questionnaire. Results The CDI Cronbach’s alpha was 0.81. The total CDI score was 9.60±7.50, 13.2% of children (boys 16.7% vs girls 9.5%) were at risk of developing depression symptoms. Overweight girls, but not boys, had significantly higher total CDI score than their normal weight counteparts. Both obese girls and boys showed a higher negative self-esteem score. More than one fifth underweight girls still wanted to be thinner while more than one third obese boys still wanted to be heavier. Children who wanted to be thinner showed slightly higher scores of ineffectiveness and negative self-esteem. After introducing the body dissatisfaction into the model, overweight was still associated with total CDI score among girls and obesity was still associated with negative self-esteem among both boys and girls. Conclusion Overweight girls show a significantly higher depression symptom score than their normal weight counterparts, which maybe partially explained by body dissatisfaction. Obese boys and girls are both more likely to suffer from low self-esteem, which is partially explained by body dissatisfaction.     

广州市肥胖及超重儿童青少年代谢综合征患病情况调查

Objective To know prevalence of metabolic syndrome (MS) and metabolic abnormalities (MA) in overweight and obese children and adolescents in Guangzhou, China. Methods Totally, 439 children and adolescents aged six to 18 years were enrolled, including 129 obese, 115 overweight and 195 normal control ones. Their body height, body weight, waist circumference, hip circumference and blood pressure were measured, as well as their fasting blood glucose (FBG), lipid profiles and oral glucose tolerance test (OGTF). Results ①Prevalence of MS in overweight and obese children and adolescents was 20.9 % (27/129) and 10.4 % (12/115), respectively, 17.9 % (35/195) and 1.6% (4/244) in those with insulin resistance and non-insulin resistance, respectively. Prevalence of MS, each component of MA and cluster of each components of MA all increased in linear trend with their body mass index (BMI) or insulin resistance increasing. ② BMI correlated with all metabolic indicators and could independently predict risk of MS. Conclusions Prevalence of MS among overweight and obese children and adolescents in Guangzhou was considerably high, and BMI can be used as a suitable index for their obesity assessment in MS diagnosis.     

Relationships between Weight Status and Bullying Victimization among School-aged Adolescents in Guangdong Province of China

Objective To examine relationships between weight status and different forms of bullying victimization among adolescents aged 11-18 years. Methods The relationships between weight status and bullying victimization （physical, verbal, and relational） were examined utilizing data from the Guangdong Provincial Youth Health Behavior Survey. Data on height, weight, and victimization behaviors were collected by self-reporting from 12 439 subjects, Х^2 test and logistic regression were used to analyze relationships between weight and bullying victimization. Results The incidence of victimization for adolescents aged 11-18 years was 8.6%, with higher rates for boys （12.4%） than for girls （4.7%）. For children with normal, overweight and obese body mass index （BMI）, the incidence rates of victimization were 8,2%, 17.3%, and 11.5%, respectively. Compared to normal weight, overweight was a risk factor for bullying victimization（OR=1.60, 95% CI： 1.18-2.17）, and it also increased children＇s risk of being teased in a hurtful way （OR=2.13, 95% CI： 1.41-3.24） and being made fun of due to physical appearance （OR=3.58, 95% CI： 2.27-5.67）. Obesity only increased the risk for children of being made tim of due to physical appearance （OR=2.45, 95% CI： 1.44-4.15）. Conclusions The victimization for children at school is common in Guangdong province, China. Overweight and obese children are more likely to be victims of bullying behaviors, especially verbal victimization.     

Report on Childhood Obesity in China （2） Verification of BMI Classification Reference for Overweight and Obesity in Chinese Children and Adolescents

Objective To verify Working Group for Obesity in China （WGOC） recommended body mass index （BMI） classification reference for overweight and obesity in Chinese children and adolescents using the data of 2002 China Nationwide Nutrition and Health Survey. Methods PediaWic metabolic syndrome （MetS） and abnormality of each risk factor for MetS were defined using the criteria for US adolescents. Definition of hyper-TC, LDL, and dyslipidemia in adults was applied as well. The average level and abnormality rate of the metabolic indicators were described by BMI percentiles and compared with general linear model analysis. Receiver operating characteristic analysis was used to summarize the potential of BMI to discriminate between the presence and absence of the abnormality of these indicators. Results There was neither significantly increasing nor significantly decreasing trend of biochemical parameter levels in low BMI percentile range （〈65th）. Slight increasing trend from the 75th and a significant increase were found when BMI≥85th percentile. In general, the prevalence of the examined risk factors varied slightly when BMI percentile〈75th, and substantial increases were consistently seen when BMI percentile≥75th. As an indicator of hyper-TG, hypertension and MetS, the sensitivity and specificity were equal at the point of BMI〈75th percentile, and the Youden＇s index of risk factors also reached peak point before 75th percentile except for MetS. When the BMI percentile was used as the screening indicator of MetS, Youden＇s index reached peak point at 85th percentile, just the point in the ROC graph that was nearest to the upper left comer. Conclusion The BMI classification reference for overweight and obesity recommended by WGOC is rational to predict and prevent health risks in Chinese children and adolescents. Lower screening cut-off points, such as 83th percentile or 80th percentile, should not be excluded when they are considered as overweight criteria in future intervention or prevention studies.     

Ethnic Differences in Body Mass Index and Prevalence of Obesity in School Children of Urumqi City, Xinjiang, China

Objective To investigate the prevalence of obesity and distribution of body mass index （BMI） in school children of four ethnic groups in Urumqi, Xinjiang, China. Methods A total of 55 508 school children of Han, Hui, Uygur and Kazak nationalities aged 8-18 years were selected by a cluster sampling from a districts of Urumqi City for anthropometrie measurement and demographic survey. Prevalence of obesity and overweight and distribution of body mass index （BMI） by gender, age, and nationality were analyzed and compared. Cutoff points of BMI for defining obesity and overweight were based on the proposal set by the Working Group on Obesity in China （WGOC） to assess age-, gender- and nationality-specific prevalence of obesity and overweight. Results Prevalence of obesity was 5.34%, 6.78%, 3.39 %, and 1.22% for boys and 2.61%, 1.83%, 1.78%, and 1.40% for girls of Han, Hui, Uygur and Kazak nationalities, respectively. Prevalence of obesity tended to decrease with age overall, whereas that of overweight increased with age in Han children. Conclusions Prevalence of obesity in school children in Urumqi varies with their nationalities and is lower than that of an average national level and a level of western countries. Obesity is more prevalent in boys than in girls of Urmuqi overall, which is just the opposite in Kazak children. Han boys and Hui girls have the highest prevalence of obesity and Kazak boys and girls have the lowest ones. Prevalence of obesity decreases with age, but that of overweight shows a different trend.     

Dairy Consumption and Associations with Nutritional Status of Chinese Children and Adolescents

Objective This study aimed to describe frequency and quantity of total dairy consumption of Chinese children and adolescents and explore the associations between dairy consumption and nutrition status, including stunting, wasting, overweight, and obesity. Methods Participants included 28,250 children and adolescents aged 6-17 years old. A food frequency questionnaire(FFQ) including 100 kinds of food was used to collect information about frequency and quantity of dairy consumption. Determination of stunting was with a height cutoff value for age and gender, and determination for wasting, overweight, and obesity was with BMI for age and gender. Results Of the total sample, 36.1% of children aged 6-17 reported consuming dairy food more than once per day(≥ 1/day). The average total dairy intake of all the participants was 126.7 g/day. For boys, dairy consumption had an inverse correlation with stunting and wasting after controlling for confounders. For girls, dairy consumption was negatively associated with stunting and obesity after controlling for confounders as above. Conclusion Dairy consumption in Chinese children and adolescents was relatively lower than that in developed countries, and was negatively associated with stunting and wasting for boys and with stunting and obesity for girls.     

Nutrition in Chinese-Korean Children and Adolescents

ObjectiveTo study the nutrition habits among Chinese-Korean children and adolescents in Yanbian Autonomous Prefecture, Jilin, China. MethodsData were obtained from the Chinese National Survey on Students’ Constitution and Health in 1995, 2000, 2005, and 2010 for Chinese-Korean children and adolescents aged 7-18 years.The number of the subjects included was 4789, 4704, 5875, and 5315, respectively. ResultsThe rate of the occurrence of stunting showed a declining trend from 1995 to 2010 (for boys:urban, 6.3%; rural, 12.7% in 1995 and 3.5% for both in 2010. For girls: urban, 7.8%; rural, 13.4% in 1995 and 4.2% and 5.5%, respectively, in 2010). Although the ratio of wasting did not show significant differences between the urban and rural children and adolescents in 1995, 2000, 2005, and 2010 respectively, the ratio of occurrence of overweight or obesity increased (for boys: urban, 7.3% and 1.3%in 1995, 17.6% and 12.9% in 2010; rural, 7.0% and 1.3% in 1995, 14.6% and 12.8% in 2010, respectively. For girls: urban, 8.1% and 1.0% in 1995, 17.3% and 8.6% in 2010; rural 5.7% and 0.7% in 1995, 16.4%and 7.4% in 2010, respectively). ConclusionThe ratio of malnutrition in children and adolescents in Chinese-Korean areas declined from 1995 to 2010, and the distinction in malnutrition between the urban and rural areas was negligible in 2010. Further, the ratio of overweight and obesity increased over this period.     

Risk Factors for Cardiovascular Disease in Obese and Normal School Children：Association of Insulin with Other Cardiovascular Risk Factors

Objective To investigate the level of insulin and other known cardiovascular risk factorsinschool childreg and their association with obesity.Design Cross-sectional study.Subjects 123 normal and 16 obese school children categorized by weight-for-height, mean age :10.2and 10.5 years old respectively.Measurements Family histories of diseases by questionnaires;blood pressure(BP) and waish and hip ciecumferences by measurements;fasting blood for glucose,insulin,total cholesterol,HDL-cholesterol and triglycerides.Results The numbers of boys in the normal and obese group were 65 and 58,those of the girls ,53 and 63 respectively.The obese group was more likely to have family histories of obesity,high blood pressure and diabetes;had significantly greater waist-hip-ratio(WHR) ,higher systolic and diastolic BP,lower HDL-cholesterol,higher triglyceride and fasting insulin levels (with fasting blood sugar in the normal range) than the normal weight group.In a crude analysis,insulin levels were positively correlated with obesity,systolic BP,WHR,age and triglycerides and negatively associated with male gender and HDL-cholesterol.After aduustment using multiple regression,only obesity status ,age,gender and triglycerides still remained significantly associated with insulin level.Limitation of utilizing family remained significantly associated with insulin level.Limitation of utilizing family disease history report for identification of children at risk was discussed.Conclusion These findings suggest that risk to coronary heart disease and hyperten-sion through insulin resistance already operates in school-aged children.     

Prevalence and Correlates of Elevated Blood Pressure in Chinese Children Aged 6-13 Years:a Nationwide School-Based Survey

Objective To estimate the prevalence of elevated blood pressure (EBP) in Chinese children and identify individual and family factors associated with EBP.
Methods A nationwide cross-sectional study was conducted in 2010 using stratified cluster sampling. Participants’ blood pressure was measured, and their parents completed a questionnaire on personal and family characteristics. Prevalence and correlates of EBP were assessed.
Results Among a total of 24,333 participants, 20.2% of boys and 16.3% of girls had EBP. The prevalence of EBP increased with the ascending trend of waist circumference, Waist-to-height ratio, and body mass index. The adjusted prevalence ratios (aPRs) for obese boys and girls were 2.50 and 2.97, respectively. Fewer urban boys (16.2%) had EBP than rural boys (21.7%). Boys with a family history of hypertension were 12%more likely to have EBP. Children whose mothers received a college education tended to have lower likelihood of EBP;with an aPR was 0.85 among boys and 0.78 among girls.
Conclusion EBP is common among obese students and those who have a family history of hypertension. A negative association between mothers’ education levels and EBP risk in children was found.     

Overweight and obesity prevalence rates among youth in the Carolinas

Overweight and obesity have become major public health concerns in the United States, reaching epidemic proportions among adults and children in recent years. According to the most recent national surveys, American adults have experienced a 50% increase in the prevalence of overweight and obesity. Moreover, an alarming 100% increase has been observed among children and adolescents since the 1970s. To assess the status of overweight and obesity prevalence among youth in the Carolinas, weight, height, waist, and hip circumferences were monitored during routine cholesterol screenings among 11- to 14-year-olds in two school districts. Of the twelve hundred students screened, 32.4% percent were overweight and 16.4% were obese, exceeding national averages of 22% and 11%, respectively. The overweight and obesity prevalence rates were even more dramatic when broken down by gender and ethnic/racial groups. For instance, 54% of black girls and 45% of black boys were overweight, and better than half of these students were obese. Overweight and obesity prevalence rates among black girls were nearly twice the rates observed for white girls. Ethnic differences in percentage of overweight and obese boys were not as great as those observed among girls. A number of factors may contribute to the unprecedented levels of overweight and obesity observed among American youth, including physical inactivity, poor nutritional habits (i.e., high-fat meals and snacks, and super-sizing), economic, and social factors. Consequently, the coordinated efforts of physicians, school nurses, teachers, parents, and students will be necessary to effectively address the growing problem of childhood obesity.     

重庆市城区3～18岁儿童青少年肥胖症及相关疾病的流行病学调查

目的为掌握重庆市儿童青少年超重肥胖的发病情况,并对心血管疾病相关的高危指标进行观察。方法对重庆市城区23293名3~18岁儿童青少年进行了流行病学调查。测量指标包括身高、体重、腰围、臀围、血压。结果(1)总体检出超重12.44%,肥胖为3.72%,其中男孩分别为14.38%、4.99%,女孩为10.37%、2.35%。(2)肥胖组及超重组男女儿童的收缩压及舒张压高于90百分位及95百分位者均多于正常体重组,χ2值分别为404.535、618.486,115.912、131.641,P值均<0.005。(3)腰-臀围比值肥胖男孩中有10.89%腰-臀围比值>1.0,肥胖女孩中有75.00%腰-臀围比值>0.85。结论重庆市城区儿童青少年超重检出率为12.44%,肥胖检出率为3.72%。肥胖儿童中的血压升高者明显的多于同年龄同性别正常体重儿童。女孩中心性肥胖高于男孩。     

Overweight and obesity status among adolescents from Mexico and Egypt

BACKGROUND: Obesity is on the rise among adults, adolescents and children worldwide, including populations living in developing countries. This study aimed to describe body mass index of adolescents from Mexico and Egypt and to evaluate non-nutritional correlates from two cohort studies. METHODS: Questionnaire data and weight and height measurements were collected in two large baseline studies in adolescents between 11 and 19 years old attending public school during the 1998-1999 school year in Mexico (n = 10,537) and the 1997 school year in Egypt (n = 1,502). The authors compared body mass index and correlates stratified by sex and country through multivariate linear regression. RESULTS: Overall prevalence of overweight and obesity was 19.8 and 7.9%, respectively, among the Mexican adolescents and 12.1 and 6.2%, respectively, among the Egyptian adolescents. Based on U.S. Centers for Disease Control and Prevention (CDC) definition growth charts, for Mexico 18% of boys and 21% of girls were overweight and 11% of boys and 9% of girls were obese. In the Egyptian sample, 7% of boys and 18% of girls were overweight and 6% of boys and 8% of girls were obese. The most consistent correlates of body mass index in the Mexican population were age, years of education, smoking, vitamin intake and participating in sports, whereas the factors correlated among Egyptian adolescents were age and rural residence. CONCLUSIONS: Obesity and overweight are becoming a problem among Mexican and Egyptian youth. Information about the risk factors associated with excessive weight gain during the adolescent period is a first step towards proposing prevention strategies.     

Report on childhood obesity in China (7). Comparison of NCHS and WGOC

OBJECTIVE: To test the validity of Working Group on Obesity in China (WGOC) reference in screening childhood obesity using obesity-related metabolic syndrome (MS) and its components as disease risk evidence. METHODS: A total of 2020 adolescents (1007 boys and 1013 girls) aged 14-16 years were sampled in Beijing, China. Anthropometric and biochemical measurements, as well as blood pressure parameters were available. Prevalence of overweight/obesity and related MS risk factors were analyzed across different body mass index (BMI) categories. The sensitivity and specificity of the WGOC cut-offs were compared with those of National Central Health Statistics (NCHS). RESULTS: Significantly high prevalence of MS and its components were found both in the obesity and overweight groups, which were classified by the WGOC and NCHS references. Similar distribution pattern of MS risk factors existed among different BMI categories, but the frequency and clustering of these factors in the obesity group classified by the NCHS were much higher. Owing to its irrelevant high cut-offs for overweight/obesity (especially for girls since the mid- adolescence), the NCHS reference had a high specificity but a low sensitivity. By contrast, the WGOC reference with a high sensitivity (90.1% for boys and 89.2% for girls) and a relative high specificity (96.4% and 92.8% for obese boys and girls, 78.1% and 68.9% for overweight boys and girls respectively) was more suitable to support the need for early screening, intervention, and treatment of childhood obesity in China. CONCLUSION: High sensitivity is more important than specificity in choosing appropriate screening tools for childhood obesity. Validity test demonstrates that it is rational to use the WGOC reference, established on the basis of the Chinese own reference population as a uniform screening tool for childhood obesity, which can effectively overcome the unnecessary treatment and psychosocial implications of stigmatization caused by misclassification.     

广州市海珠区10～14岁小学生肥胖现状及影响因素分析

目的 了解小学生肥胖现状及影响因素。方法 在海珠区随机抽取3所小学，对1100名学生进行体格检查，并对调查对象发放有关肥胖影响因素的调查问卷。结果 本次调查肥胖检出率为5．82％，其中男生533人，肥胖检出率为6．57％；女生567人，肥胖检出率为5．11％，男女间肥胖检出率差异无统计学意义；各年龄组肥胖检出率差异有统计学意义，其中11岁组的肥胖检出率最高；对相关影响因素进行logistic回归分析，进食速度OR=1．615，家长肥胖OR=1．808。结论 不良的生活方式与肥胖的发生密切相关，进食速度、家长肥胖是肥胖的危险因素。     

吉林省延吉市儿童和青少年超重/肥胖现况调查及其影响因素分析

目的：调查2016年吉林省延吉市城区儿童和青少年超重/肥胖现状及相关的生活方式,阐明超重/肥胖的影响因素。方法：采用普查方法对吉林省延吉市城区6~17岁的儿童和青少年42 132人进行身高和体质量测量,计算体质量指数（BMI）。采用问卷调查、分层整群随机抽样方法,在参加体检调查对象中抽取10~14岁儿童和青少年1 523人,调查饮食习惯。采用中国肥胖工作组制定的标准筛查超重和肥胖,采用Logistic回归分析和中介效应分析方法筛选超重/肥胖影响因素。结果：2016年吉林省延吉市城区6~17岁儿童和青少年超重和肥胖总体检出率分别为16.7%和18.4%,超重+肥胖检出率为35.0%。男生超重和肥胖检出率（18.6%,22.0%）均高于女生（14.7%,14.4%）（P<0.01）。7~13岁男生各年龄组超重检出率均高于同年龄的女生（P<0.05或P<0.01）,男生各年龄组肥胖检出率均高于同年龄的女生（P<0.01）。男生超重检出率在12岁达到高峰,在6~10岁肥胖检出率（23.8%~25.6%）均较高,11~17岁肥胖检出率随着年龄的增长而逐渐下降。每周吃烧烤食物≥ 3次（男生OR=1.767,P=0.010,95% CI：1.148~2.719;女生OR=2.205,P=0.002,95% CI：1.327~3.664）和节食减肥（男生OR=2.113,P<0.001,95% CI：1.456~3.065;女生OR=2.128,P<0.001,95% CI：1.430~3.167）增加儿童和青少年超重/肥胖风险,每周吃甜点心≥ 3次（男生OR=0.359,P<0.001,95% CI：0.226~0.573;女生OR=0.324,P<0.001,95% CI：0.186~0.565）和按时吃三餐（男生OR=0.683,P=0.028,95% CI=0.486~0.960;女生OR=0.624,P=0.016,95% CI=0.424~0.916）可降低超重/肥胖风险。自我评价体型在超重肥胖和每天按时吃三餐之间具有完全中介效应。结论：吉林省延吉市6~17岁儿童青少年超重和肥胖检出率处于较高水平,日常饮食习惯和节食减肥是超重/肥胖的主要影响因素。     

儿童青少年超重及肥胖与代谢综合征的相关性研究

目的探讨儿童青少年超重肥胖与代谢综合征(MS)的相关性,为MS的早期干预提供参考。方法回顾性分析2007-2010年本院小儿内分泌门诊就诊的57例超重及155例肥胖儿童青少年的临床资料[血压、腰围、空腹血糖(FPG)、空腹血胰岛素(FINS)、血清甘油三酯(TG)、总胆固醇(TC)、高密度脂蛋白胆固醇(HDL-C)、低密度脂蛋白胆固醇(LDL-C)、胰岛素抵抗指数(HOMA-IR)和胰岛β细胞功能指数(HOMA-β)],以国际糖尿病联盟(IDF)的青少年MS定义为诊断标准计算MS检出率,并与同期常规体检的年龄性别匹配的228例非超重肥胖健康者进行比较。结果 (1)超重组、肥胖组与对照组比较,腰围、血压及FPG、TG、TC、LDL-C等多项糖脂代谢指标差别有统计学意义(P<0.05),但HDL-C各组间差别无统计学意义。(2)超重组、肥胖组与对照组比较,除HDL-C外其余MS各组分检出率升高,差别有统计学意义,检出率随体质量指数升高逐渐增加(趋势检验P<0.01)。(3)对照组未检出MS患者,超重组检出MS 3名(5.3%),肥胖组检出MS 56名(36.1%),MS检出率随体质量指数升高而增加(趋势检验P<0.01)。(4)超重组、肥胖组Lg HOMA-IR和Lg HOMA-β均较对照组升高(P<0.01)。(5)胰岛素抵抗指数与MS各单项指标显著相关(P均<0.01)。结论超重肥胖儿童青少年MS发生率较正常体质量者显著升高。儿童青少年超重肥胖与MS的发生密切相关,应重视并积极防治。     

广州市肥胖及超重儿童青少年代谢综合征患病情况调查

目的了解广州超重和肥胖儿童、青少年代谢综合征（MS）和代谢异常的患病情况。方法对439名6～18岁儿童、青少年（肥胖者129名,超重者115名,正常对照者195名）行身高、体重、腰围、臀围、血压测量,检测空腹血糖、血脂,并行121服葡萄糖耐量试验。结果①肥胖、超重者MS患病率分别为20．9％（27／129）、10．4％（12／115）;胰岛素抵抗者、非胰岛素抵抗者MS患病率分别为17．9％（35／195）、1．6％（4／244）。MS、各代谢异常患病率和多个代谢异常的聚集均随着体重指数（BMI）的增加及胰岛素抵抗的发生呈增加趋势。②BMI与各代谢指标的相关性更强,可独立预测MS风险。结论广州市肥胖及超重儿童、青少年MS患病率较高;BMI可作为儿童、青少年MS肥胖的评估指标。