Risk Factors Of Pre-hypertension And Hypertension And Its Relationship With Stroke Occurrence In Mongolian Population

Objective: 1. To investigate the prevalence of pre-hypertension and hypertension in Mongolian population lived in the agricultural and pastoral areas, and to compare cardiovascular risk factors, clustering of these factors between pre-hypertension and hypertension. 2. To explore association between inflammation and endothelial dysfunction biomarkers and pre-hypertension and hypertension. 3. To study whether pre-hypertension individuals have more hazards developing to stroke. 4. To study whether status of inflammation and endothelial dysfunction was associated with increased risk of stroke.Subjects and methods:1. Baseline investigation: A cross sectional survey was conducted between 2002 and 2003. In the survey, study participants aged 20 years and older were recruited from 32 villages in 2 adjacent townships located in Kezuohou Banner (county) and Naiman Banner in Inner Mongolia, and they were administered interview using a standard questionnaire, and the related physical examination and blood samples collection were conducted by trained staffs.(1) Field surveyData on demographic characteristics, family history of hypertension, smoking and alcohol consumption were obtained. Height, weight, waist circumference, hip circumference and three blood pressures were measured for all participants.(2)Laboratory testsFasting plasma glucose(FPG), insulin, triglyceride(TG), total cholesterol(TC), high-density lipoprotein cholesterol(HDL-C), low-density lipoprotein cholesterol (LDL-C), apolipoprotein A1(ApoA1), apolipoprotein B(ApoB), C-reactive protein (CRP), E-selectin, intercellular adhesion molecules-1(ICAM-1), plasma rennin activity (PRA) and angiotensin II(AngII) were detected for all participants. 2. Survey follow-up studyIn October 2008 and July to August 2009, follow-up surveys were conducted for the subjects involved in a baseline study. Failure event is defined as the first occurrence of stroke during the time from the baseline to the last follow-up. We interviewed subjects by household, reviewed monitoring data and hospital medical records to investigate stroke events using standard questionnaires.3. Statistical analysisEpidata3.0 software was used to establish a database, and all questionnaires were input after checking by two individuals. All p-values were based on a 2-sided test and a significance level of 0.05, and statistical analysis was conducted using SAS 9.1 statistical software.Results:A total of 2589 participants aged 20-84 years old, 1064 males and 1525 females, were included in the analysis.1. In the study, prehypertensives accounted for 38.39% among all participants, 38.44% in males and 38.36% in females. Hypertensives accounted for 37.39% among all participants, 45.58% in males and 31.67% in females.2. Prehypertensives had higher proportions of individuals with alcohol consumption (31.29%), overweight or obesity (23.34%), central obesity (37.63%), hyperlipidemia (25.26%), impaired fasting glucose or diabetes (17.56%) and high CRP (23.9%) than normotensives. Similarly, hypertensives had higher proportions of individuals with alcohol consumption (44.32%), overweight or obesity (37.16%), central obesity (53.52%), hyperlipidemia (37.89%), impaired fasting glucose or diabetes (25.60%) and high CRP (32.63%) than pre-hypertensives and normotensives3. Multivariate logistic regression analysis showed that pre-hypertension was associated with increasing age, male, overweight, obesity, high triglycerides, high Apolipoprotein B and high angiotensin II, and the odd ratios (ORs) and 95% confidence intervals (95% CIs) were as follows: 1.03(1.02-1.04), 2.04(1.50-2.79), 1.96(1.23 -3.13), 2.58(1.18 -5.52), 1.64(1.09-2.47), 1.99(1.03 -3.84) and 1.39(1.01 -1.89), respectively. Hypertension was positively associated with aging, male, family history of hypertension, heavy drinking, overweight, obesity, high triglycerides, Apolipoprotein B, heart rate, angiotensin II and CRP, and ORs (95%CIs) were 1.09(1.07-1.10), 2.05 (1.44 -2.89), 5.83(3.51-9.69), 2.10(1.31-3.35), 3.41(2.02-5.73), 8.16(3.69-18.01), 2.13 (1.39-3.25), 2.07(1.00-4.28), 4.16(1.29-13.44), 2.36(1.65-3.35) and 1.57(1.03-2.37), respectively.4. Prehypertensives had high clustering proportion (31.39%) of≥2 risk factors, including overweight or obesity, central obesity, impaired fasting glucose or diabetes and hyperlipidemia, than that in normotensives (21.25%), and hypertensives had high clustering proportion (49.43%) than prehypertensives and normotenives. Compared with none risk factors clustering group, 1, 2 and≥3 factors clustering groups had the ORs (95%CIs) of 1.56(1.19-2.06), 1.89(1.38-2.59) and 2.57(1.61-4.09) for pre-hypertension, respectively; and ORs(95%CIs) of 1.98(1.44-2.73), 3.46(2.47-4.97) and 7.58 (4.69-12.26) for hypertension, respectively.5. Prehypertensives had high clustering proportion (22.36%) of≥2 risk factors, including high levels of angiotensin II, high CRP, ICAM-1 and low levels of PRA, than that in normotensives (13.40%), and hypertensives had high clustering proportion (37.94%) of the biomarkers than prehypertensives and normotensives. Compared with none risk factors clustering group, 1, 2 and≥3 biomarkers clustering groups had the ORs (95%CIs) of 1.17(0.93-1.49), 1.40(0.99-1.97) and 2.61(1.17-5.82) for pre-hypertension, respectively; and ORs (95%CIs) of 0.85(0.64-1.13), 1.42(1.04-2.20) and 4.98 (2.26-11.00) for hypertension , respectively.6. During follow-up, 78 new stroke cases occurred among 2589, 41 cases were ischemic stroke and 35 cases were hemorrhagic stroke, and 2 cases of sub-type were unknown. The incidence density of stroke was 476.91/100 000 person-years, which were 809.19/100 000 person-years in men and 255.28/100 000 person-years in women. The incidence densities of ischemic and hemorrhagic stroke were 250.80/100000 person-years and 213.38/100 000 person-years, respectively.7. The incidence density of stroke was 25/100 000 person-years in normotension group, and 282/100 000 person-years in pre-hypertension group. Compared with normotensives, prehypertensive individuals had a hazard ratio (HR) of 11.3 for stroke. Attributable risk percent (ARP) was 91% and population attributable risk percent (PARP) was 20% for stroke in pre-hypertensive population. The incidence density of stroke was 987/100 000 person-years in hypertension group. And the HR for stroke was 39.7, compared to normotensives. Moreover, ARP was 97% and PARP was 74% for stroke in hypertensives. 8. The population was divided into four groups according to baseline CRP quartile, and the lowest quartile as the reference group, the highest group had the HR of 2.96(95%CI: 1.17-7.46) for ischemic stroke, but adjusted for age and sex, HR value(1.89, 95%CI: 0.75-4.76)was no more statistically significant. Association between the baseline serums AngII, ICAM-1, E-selectin and the incidence of stroke has not been found statistically significant.Conclusion:1. The prevalence rates of pre-hypertension and hypertension are relatively high in Mongolia population. Pre-hypertensive population has higher levels and aggregation extents of cardiovascular risk factors than those with normotension. Thus, cardiovascular risk factors and clustering of these factors are existed in the stage of pre-hypertension.2.Individuals with high levels of CRP and AngII have increased risk of suffering from pre-hypertension, inflammation or endothelial dysfunction may play a role in the development of hypertension.3. The incidence of stroke is high in the study, and Stroke has become an important disease and public health issues threaten to the health and lives of local Mongolian.4. Compared with normal blood pressure, baseline pre-hypertension and hypertension groups have higher incidences of stroke and hazard ratios for stroke. So, pre-hypertensive group had higher risk of stroke occurrence, and pre-hypertension is a major risk factor for stroke.