The Impact Of Household Income And Education Level On BMI And Its Change Characteristics Among The Middle-aged Residents

Objective:Through the research,we aim to analyze the level of Body Mass Index(BMI)and its change rate for 12 years from 2000 to 2011 among the middle-aged in China.To explore the influence of household income,education level and demographic characteristics on BMI and its change characteristics among the middle-aged people,and to explore the analysis method of the influencing factors of BMI and its change characteristics.Methods:We collected the data of China Health and Nutrition Survey for five times which conducted seperately in the year of 2000,2004,2006,2009 and 2011;The middle-aged residents aged between 45 and 65 in 2000 were included in the study as the research subjects with a total of 1506 adults(male 663,female 844).At first,descriptive analysis was conducted for different variables included.Then consider BMI as the dependent variable,variables that changed over time such as household income,household size,marriage status,working condition,smoking,drinking as the covariates of the first level,and variables that didn’t change over time like sex,baseline age,education level,residential area as variables of the individual level to investigate the difference of BMI in intra-individual and inter-individual using the two-level model.Results:1.During the period from 2000 to 2011,the BMI of the middle-aged population showed a slow growth trend of the quadratic function,the formula was2 20 1 20.05Y(23.314 0.003)()2ij ij ij j j ij j ij ij(28)(10)T(10)T(10)m(10)mT(10)mT(10)r and its intercept,the coefficient of linear term and the quadratic item were all statistically significant;the BMI level increased from 23.31 kg/m2 to 23.38 kg/m2.2.The higher the education level was,the higher the BMI was(b=0.27,P<0.001),and the more slowly the BMI increased(b=-0.02,P=0.005).At the same time,the higher the family income,the higher the BMI(b=3.41×10-5,P=0.049).3.Among the middle-aged object,the older the people,the lower the BMI(b=-0.03,P=0.038),while the greater the age was,the slower the growth rate of BMI was(b=-4.37×10-3,P<0.001);The average BMI level was higher among the women than that among the men(b=0.56,P=0.002),but there was no significant statistical difference that BMI changed with time between the women and the men(b=-0.03,P=0.100);When compared with Central China(b=-0.724,P=0.002),Southern China(b=-2.623,P<0.001)and the Southwest(b=-1.589,P<0.001),the average BMI of the Northeast was higher.The average BMI level of the current working people was relatively low(b=-0.13,P=0.011).4.Smokers had lower BMI than those who had never smoked(b=-0.31,P=0.002),and there was no significant statistical difference in BMI between ex-smokers and people who had never smoked(b=-0.12,P=0.336);No significant statistical difference was found between the BMI of the drinkers and persons who didn’t drink(b=-0.01,P=0.894).Conclusions:1.The higher the education level or the household income is,the higher the BMI is;while the higher the education level is,the more slowly the BMI increases with time.The problem of health inequalities like obesity may shift to the vulnerable groups such as people with less family income or lower education level.2.People who are women,live in the Northeast or have no job have the higher BMI;The older the object is,the lower the BMI,and the more slowly that BMI grows.3.BMI of the respondents who are current smoking will be reduced compared to those who have never smoked,after quitting smoking BMI will increase.