Risk Factors Of Fatty Liver: A Case-control Study Based On Healthy Examination People

Fatty liver is one of the common chronic hepatic diseases,which covers a high prevalence rate in both American-European countries and China.Due to the improvement of living standard,the change of dietary structure and the relative lag of preventive health care,the prevalence rate of fatty liver tends to increase and the patients tend to be younger in recent years.The clinical epidemiology research shows that prevalence rate of fatty liver is about 20%in American-European countries.But in China,considerly different occupation,age,gender and area of the respondents,the rate varies from 0.27%to 25%.Although a consistent report on the gender distribution of fatty liver has not been reached at present,most experts consider that men are much easier to be attacked by fatty liver than women.There are few researches in the occupational distribution of fatty liver,but indicate that the rate differs in occupations. The comparatively definite risk factors of fatty liver include obesity,hyperlipidemia, type 2 diabetes and insulin resistance,overdrinking,etc.Whether hypertension, gallstone,hyperuricemia,coronary heart disease and smoking are the risk factors of fatty liver hasn't been defined,though some researchs have been carried out in recent years.Fatty liver is not an independent disease on clinic but a pathological state that hepatic fatty accumulates too much for various reasons and it could be accompanied or not accompanied by clinical manifestation.Since it lacks specificity of clinical manifestation,the disease is likely diagnosed when people do health examination or get medical treatment for other diseases.Without any effective remedy for fatty liver at present,the main method relies on prevention,so the study of epidemiology of fatty liver has been drawing much attention.This dissertation,taking 2536 persons who did health examination in Hangzhou navy sanatorium from July 1st to December 31st in 2006 as the study object,analyzes the status and risk factors of fatty liver by epidemiological questionnaire,index of somatology,laboratory diagnosis,B-ultrasound and electrocardiographic examination, so as to find a scientific foundation for pertinent prevention and treatment measures of the disease.Material and MethodsStudy object:2536 persons who did health examination in Hangzhou navy sanatorium from July 1st to December 31st in 2006.Disease sample:random fatty liver sampling from the study object,compared with random non-fatty liver sampling from the same group.The investigation covers five aspects.First,to adopt an identically-designed epidemiology questionnaire,comprising general information,workplace or residential commumity,occupation,disease history and habit of smoking or drinking.Second,to make use of somatology targets which are made up of height,weight,blood pressure and weight index.Third,to carry out laboratory tests,including blood fats,serum uric acid and fasting blood glucose,etc.Fourth,to get B-ultrasonic examination on liver, gallbladder,spleen and kidney.Fifth,to receive ECG examination.Professionals transfer all the data to EXCEL database by computer,check and then make statistics analyses.Data analyses are composed of descriptive study and case-control study.Descriptive study refers to the general health condition of the study object,including the prevalence rate of fatty liver according to age,gender, occupation and disease cause.In terms of case-control study,a fatty liver case and its control are first defined,followed by checking age and gender of the two groups for equilibrium,then OR is described for the strength of association between the disease and exposure by using single-factor non-conditional logistic regression analysis, finally by using multi-factor non-conditional logistic regression analysis of the all independent variable,the different function of every factors in the model is judged by OR,the variables are selected by backward methods.Single-factor and multi-factor non-conditional logistic regression analysis are both conducted by SPSS13.0.Results1.Descriptive analysis:There are totally 2536 people in this investigation,including 1384 of man and 1152 of woman,the median age is 48 years old,the proportion of male and female is 1.20 to 1.Total prevalence rate of the disease is 25.24%,the prevalence rate of male and female is 33.67%and 15.10%respectively.The male prevalence rate is remarkably higher than that of female(χ~2=144.066,P＜0.001).There is a statistical significance of the age-compared difference between the fatty liver sampling and non-fatty liver sampling of male and female.Total prevalence rate of 50～group is top of 42.02%, male prevalence rate of 50～group is top of 60.36%and female prevalence rate of 70～group is top of 36.67%.The prevalence rate of enterprise managing staff is top of 44.44%by different occupation,and the prevalence rate of enterprise units staff is bottom of 18.13%.The prevalence rate of non-alcoholic fatty liver and alcoholic fatty liver is 23.06%and 0.47%respectively.2.Case-control study:It shows fatty liver has a close relationship with overweight,obesity,hypertension, hyperglycemia,diabetes,abnormal blood lipids and hyperuricemia by using single-factor analysis.The OR is 3.60,10.15(χ~2=77.76,P＜0.001),1.72(χ~2=7.26, P=0.007),5.45,6.12(χ~2=33.36,P＜0.001),3.64(χ~2=38.89,P＜0.001),3.44(χ~2=15.23, P＜0.001)respectively.Multi-factor analysis indicates that the following five factors:overweight,obesity, abnormal blood lipids,hyperglycemia and diabetes enter into regress equation.All the regress coefficients are positive.It shows that the five factors are the independent risk factors of fatty liver.The OR is 3.18(P＜0.001,95%CI 1.78～5.69),7.91(P＜0.001,95 %CI 4.45～14.04),2.56(P＜0.001,95%CI 1.61～4.07),4.26(P=0.004,95%CI 1.59～11.38),4.54(P=0.003,95%CI 1.68～12.26)respectively.ConclusionThe prevalence rate of fatty liver of healthy examination people is comparatively high,the disease is mainly nonalcoholic fatty liver.Total and male prevalence rate was seen at top in 50～group respectively and female prevalence rate was seen at top in 70～group.Difference of prevalence rate of fatty liver has statistical significance according to different gender,age and occupation.It shows fatty liver has a close relationship with overweight,obesity,hypertension,hyperglycemia,diabetes, abnormal blood lipids and hyperuricemia.Multi-factor analysis indicates that the following five factors:overweight,obesity,abnormal blood lipids,hyperglycemia and diabetes are the independent risk factors of fatty liver.Insulin resistance is the main pathophysiologic mechanism of fatty liver.In order to control the disease,it should be prevented from different factors such as positive control of overweight,obesity,hyperglycemia,diabetes and abnormal blood lipid.