| Objective To study equities and their change trends in Chinese children and adolescents aged 7-18 years during 1985-2014,to explore the changes of differences in children and adolescents who living in urban and rural areas and different provinces by using indicators of growth and development,and to provide a theoretical basis for improving the health equity of children and adolescents.Methods On the base of data from 7 successive cross-sectional surveys of the Chinese National Survey on Student’s Constitution and Health(CNSSCH)conducted in 1985,1991,1995,2000,2005,2010 and 2014,including students aged 7-18 years from all national provinces except Tibet and Taiwan province.The samples in 7 surveys are as follows: 409946、140665、209410、216668、234421、215319、211054.Using stratified cluster sampling method and all subjects were divided into four subpopulations(urban male,urban female,rural male and rural female)by areas of residence and sexes.Each subpopulation were divided into 12 age groups by their age and economic indicators were from national statistical database.All data were analyzed by SPSS18.0 and Excel software and using the range method(absolute difference and ratio difference),the coefficient of variation and concentration index to explore the equities in China.The absolute difference and ratio difference of the height,weight and chest circumference of children and adolescents between urban and rural areas were calculated from 1985 to 2014,and the characteristics and change trends of the difference was analyzed.The absolute differences were analyzed by Z test to determine whether there is any statistical significance.The coefficients of variation(CV)of the height,weight and chest circumference within urban and rural areas were computed and compared.Analyze the change trends of the absolute differences and ratio differences of height,weight and chest circumference between students who live in Shanghai(the highest per capita)and Guizhou(the highest per capita GDP)provinces during 1985-2014.The absolute differences were analyzed by Z test.The concentration indexes of height,weight and chest circumference of students aged 7-18 years old in China were calculated from 1985 to 2014.Results 1.During 1985-2014,the height difference between urban and rural children and adolescents reduced year by year,the average difference(urban-rural)reduced from 4.24 cm to 2.41 cm and 3.72 cm to 1.99 cm in boys and girls,respectively.The average ratio(urban/rural)reduced from 1.03 to 1.016 and 1.027 to 1.014 in boys and girls,respectively.The difference between urban and rural children ‘s weight became larger in the first 15 years and narrowed in the latter 15 years,while the difference increased in 2014 compared with that in 1985.The differences in chest circumference had similar change trends.The average difference in weight between urban and rural students increased from 1.84 to 3.01 kg and 0.97 kg to 1.80 kg in boys and girls,respectively.The ratio in weight increased from 1.055 to 1.069 in boys and 1.036 to 1.045 in girls,respectively.The difference in chest circumference between urban and rural students increased from 0.65 cm to 2.04 cm in boys and-0.25 to 1.17 cm in girls,the average ratio increased from 1.009 to 1.028 in boys and 0.998 to 1.017 in girls,respectively.The increase of the weight and chest circumference was more obvious in the older age groups of urban students who changed the condition of fall behind.2.The coefficients of variation of height within rural students were larger than that of urban,which means height inequalities were larger in rural areas.This phenomenon was more obvious in the smaller age groups while late adolescents in urban and rural areas had similar and small coefficients of variation of height.During 1985-2014,different age groups exert different change trends of inequities,namely the inequities in adolescents were decreased,in 7-11 years students were increased and then dropped with an overall trend of increase over 30 years while the inequities in 16-18 years students were increased year by year.The coefficients of variation of weight and chest circumference within urban students were larger than that of rural,which means weight and chest circumference inequalities were larger in urban areas and the coefficients were increasing gradually over the 30 years.The rate of increase in weight and chest circumference among urban students slowed after 2005,while rural students had a relatively higher rate of increase in inequities.So by 2014,the coefficients of variation of weight and chest circumference in rural areas were close to that in urban.3.Students living in Shanghai have higher level of physical growth than that in Guizhou.The height of Shanghai urban boys,urban girls,rural boys and rural girls were respectively 7.46 cm,5.83 cm,6.5 cm and 6.17 cm in 1985 and became 7.34 cm,6.29 cm,9.04 cm and 7.62 cm higer than Guizhou students in 2014.The differences of weight between two provinces among four subpopulations were 4.58 kg,2.84 kg,2.29 kg,1.49 kg in 1985 and 7.64 kg,5.03 kg,9.57 kg,6.11 kg in 2014.The differences of height and weight between Shanghai and Guizhou rural students increased over the 30 years and the differences between the two provinces were larger in rural students than in urban students after 2005.However,the difference of height and weight between Shanghai and Guizhou students narrowed in recent several years.The The difference in chest circumference between the two provinces boys were larger than girls.The boys of all age groups living in Shanghai had greater chest circumference than that in Guizhou with an average difference of 2.82 cm and 1.19 cm in urban boys and rural boys,respectively in 1985,while the difference become 6.07 cm and 6.59 cm in 2014.The chest circumference of girls did not have such an evident difference between the two provinces and Guizhou girls of older age groups had greater chest circumference than Shanghai girls.The difference of chest circumference between Shanghai and Guizhou urban students was greater than that of rural students in 1985-2000,but after 2005,on the contrary,the difference between rural students was greater than that in urban students,which was more obvious in the lower age groups.4.During 1985-2014,the concentration indexes of height,weight and chest circumference were positive(except the chest circumference of 16-18 years adolescents)which means children with better socioeconomic status also have better level of physical growth and development.For 7-12 years children,the concentration indexes of height were large and they increased with age and rural children had greater height concentration indexes than urban children.Boys had greater height concentration indexes than girls at puberty and the concentration indexes of height had a slight increase over the 30 years.Male adolescents aged 12-18 years had greater concentration indexes in weight and chest circumference than female adolescents.During 1985-2005,urban and rural students had similar concentration indexes in weight and chest circumference or urban students had slight greater indexes,while rural students had obvious greater concentration indexes than urban after 2005.The concentration indexes of weight of Chinese children and adolescents increased constantly during 1985-2005 and then decreased slightly.The concentration indexes of chest circumference increased constantly during 1985-2010 and then decreased slightly(except rural boys).But the concentration indexes of weight and chest circumference became larger in 2014 compared with 1985 which means inequities in weight and chest circumference increased over 30 years with a narrowing trend in recent few years.Conclusion 1.The height difference between urban and rural children and adolescents decreased constantly,while the weight and chest circumference difference between urban and rural students increased during 1985-2000 and decreased slightly during 2000-2014.The inequalities between urban and rural children were smaller recently.2.The inequities in height were larger in rural students than urban students,while inequities in weight and chest circumference were larger in urban areas than rural and the inequities increased obviously in rural areas in recent few years.So the inequalities among rural children should be paid more attention.3.There are differences in physical growth and development between Shanghai(the highest per capita GDP)and Guizhou(the lowest per capita GDP).From 1985-2014,the difference in height and weight between the two provinces urban areas increased and the chest circumference difference between the two provinces boys increased as well.We should take some measures to improve the growth and development of children in Guizhou rural areas.4.The higher level of height,weight and chest circumference are concentrated in the children and adolescents with better social economic conditions.Over the 30 years,the inequalities of weight and chest circumference have been increasing while in recent years,there has been a narrowing trend. |
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