A Study On The Risk Factors Of Essential Hypertension Patients On The Similar Genetic Condition

PrefaceEssential hypertension (EHT) is one of the most common cardiovascular diseases. EHT is harmful to human health and has been become a great problem to public health. It has been paid general attention increasingly. However, common people know little about the severity of EHT. EHT is an important risk factor of other cardiovascular and cerebrovascular diseases. It is necessary to investigate the etiology of EHT thoroughly in order to prevent the onset of EHT, thereby decreasing the prevalence rate of cardiovascular and cerebrovascular diseases.Multidisciplinary research had approved: EHT is induced by multiple factors. That is, EHT is caused by the long-term interaction of genetic and environmental factors. But some people haven't become EHT patients on the similar base of EHT familial inheritance. The difference between these people and EHT patients should be paid general attention. There are not many studies on the independent effect of the environmental factors about EHT at present. Our research selected the sibs and divided the subjects into two groups, case group (EHT patients) and control group (health adults). The two groups had the similar genetic background, so we could investigate how the environmental factors induce EHT.Subjects and Methods1,The method of selection and standard of study populationUsing the method of cluster multi-stage sampling method, 11 villages were randomly selected in ZhangWu County. All the people above 18 years old from the 11 selected villages were investigated. People with liver disease or nephritis were excluded. Secondary hypertension patients were also excluded. Among the patients of EHT according with diagnostic criteria, the family which had patients in two successive generations, the first generation had one patient at least and the secondary generation had two or more patients could be a family constellation of EHT. The sibs in the family (one was EHT patient and the other is health adult) who were age-matched and lived alone were selected to make up the case group and the control group (60 paired groups) which the constituent ratio of male and female was 1:1.2,The contents of epidemiological surveyQuestionnaires were filled by means of inquiring and measurement in sites. The contents of survey included: general characteristics, alcohol intake, smoking habits, EHT prevalence of family members, previous disease history and so on, measurement of the blood pressure, body height and weight.Five milliliters blood samples were drawn after an overnight fast. After centrifugation, the serum fraction was removed and frozen in aliquots at -20°C until assayed. The serum was used for the measure of hematological biochemistry assay related to EHT.3,Diagnostic standard and chemical measurementsThe diagnostic standard of EHT: According to 1999 WHO-ISH guidelines for the management of hypertension, hypertension was defined as a systolic blood pressure (SBP)≥140mmHg and/or a diastolic blood pressure (DBP)≥90mmHg. The measurement of blood pressure should be carried out according to the unified standard under standard conditions.Cholesterol(CHOL), triglyceride(TG), high density lipoprotein (HDL), low density lipoprotein(LDL), serum sodium, serum potassium, serum calcium were measured by automatic biochemistry analyzer 7150( HITACHI, Japan), the blood sugar was measured by blood sugar analyzer(Johnson & Johnson, America).4,Statistical methods A database was created by FoxPro after quality examination of data. Student's t-test was used to assess differences between groups for two continuous variables. Nonparametric test was used to assess differences between groups for multiple continuous variables allowing for unequal variances. McNemar test was used to assess difference between the two paired groups. Multiple conditional Logistic regression was used when evaluating the effect of a continuous or categorical covariates on a dichotomous outcome. The soft ware used was SPSS12.0.A 2-sided value of P＜0.05 was regarded as statistically significant.Results1,The genealogical distribution and the population's pathogeneticcondition(1) The genealogical distributionThe study obtained 57 families which were consistent with the requirement of genealogy. The minimum number of the domestic members was 4 and the maximum was 11. The number of families with 6 domestic members was maximum and the number of families with 11 domestic members was minimum. The number of families with 4 patients was maximum.(2) The distribution of the families with different family historyThe number of the families in which the parents were both EHT patients was maximum. The number of families in which the father or the mother was EHT patients was equal.(3) Pathogenetic condition in different number of the domestic membersThe number of EHT patients was 260 and the number of health adults was 150, the prevalence was 63.4%.2,The compare of age between case group and control groupThe average age of case group is 45.07±9.47 and the average age of control group is 41.55 + 10.879.There was no statistical difference of age (P>0.05) between case group and control group.3,Monovariate analysis on the related risk factors of EHTThere was no statistical difference of Smoking, drinking, blood fat, blood sugar, serum potassium, serum sodium, serum calcium between case group and control group (P>0.05). There was statistical difference of BMI (P<0.05) between case group and control group. It was a risk factor of EHT, OR=11.870 (95% C.I : 1.427～98.712).4,Multivariate conditional Logistic analysisMultivariate analysis was conducted on all the factors. We used conditional Logistic regression analysis to constitute model of EHT. Compared with low level of BMI, high level of BMI was a risk factor of EHT, OR=29.330 (95% CI :2.594～331.613).DiscussionThe number of the families in which the parents were both EHT patients was maximum. The number of EHT patients was 260 and the number of health adults was 150, so the prevalence was 63.4%. It illustrated that the number of domestic members was concerned with the prevalence of EHT.Some studies had made it clear that EHT was polygenic inheritant disease and the connection of the genetic factors and the environmental factors induced it. The effects of the genetic factors had been generally acknowledged. But those researches on the effects of environmental factors selected the EHT patients and the health adults among the common population to make up the case group and the control group and couldn't exclude the effects of genetic factors, therefore couldn't determine the independent effects of the environmental factors. My research selected sibs, EHT patients made up the case group and health adults made up the control group, and the two groups had the similar genetic background, we can approach the independent effects of the environmental factors.Up to now, the correlation between drinking and blood pressure has been approved, but in this study they were independent, perhaps owing to we didn't divide capacity for liquor into different layers, accordingly the result needs adjustment. The correlation between smoking and blood pressure has not been approved. In this study they were independent, the relation between them needs deep research. In this study there was no statistical difference of blood sugar, CHOL, TG, LDL, HDL between case group and control group. There was no statistical difference of serum potassium, serum sodium, serum calcium between case group and control group too. This study collected the data of genealogy and the blood, so the sample size is small, which may influence the validity of the findings. This research found that BMI was an independent risk factor. The subjects of the study were the sibling who lived alone for many years and the genetic background was similar, so the effects of genetic factor on the difference of BMI between the two group should be excluded, thus we believe that the different living environment cause the difference of BMI. This hinted that the crowd should control their body weight which had important effect of preventing the onset of EHT. Especially the EHT patients should control their body weight as far as possible and keep their weight within the normal range.ConclusionOn the similar genetic background, we analyzed the effect of the environmental risk factors and we could draw a conclusion that BMI was a risk factor of EHT.