| ObjectiveWith the improvement of social economy and people' s living standard,China' s elderly population is increasing and has become the country with the largest elderly population in the world,and has entered an aging society.For the elderly,an important feature is that as they get older,arterial elasticity will decrease accordingly,resulting in higher systolic blood pressure,lower diastolic blood pressure and simple systolic hypertension.At the same time,the elderly are often the population with high incidence of hypertension.The following problem is that diastolic blood pressure may be too low during antihypertensive treatment.Whether there will be a J-curve is worth paying attention to.In addition,major hypertension guidelines at home and abroad often focus only on systolic blood pressure,less on diastolic blood pressure,and the target of diastolic blood pressure is unclear.Therefore,this study selected 787 elderly inpatients aged ?65 years who lived in Guangzhou for a long time from January 2003 to December 2008 from Guangzhou General Hospital of the former Guangzhou Military Region for health check-up and follow-up,aiming at analyzing the influencing factors of diastolic blood pressure in the elderly population and its influence on survival prognosis,discussing the appropriate diastolic blood pressure level in the elderly population,and providing help for the diagnosis and treatment of clinical elderly hypertensive population.MethodsA general health survey was conducted on the retired elderly patients aged?65 years who lived in Guangzhou for a long time from January 2003 to December 2008 in the former Guangzhou General Hospital of Guangzhou Military Region.All the enrolled patients were documented and followed up until December 31,2018.The follow-up method is to conduct a physical examination and follow-up once a year at the community retirement homes.The follow-up personnel directly ask the patients face-to-face at the retirement homes or follow-up by telephone.The detailed information of the end-point events during the follow-up period is obtained by consulting the health care doctors at the retirement homes,or the relevant hospitalization data of the patients are retrieved through the hospital's hospitalization system.During the annual physical examination,the subjects were investigated with questionnaires to complete the "survey table of cardiovascular and cerebrovascular diseases and risk factors in the elderly",and the ambulatory blood pressure,office blood pressure monitoring,uric acid,creatinine,urea nitrogen and other blood indexes were measured.then,according to the diastolic blood pressure level in the office of the study population,the diastolic blood pressure was divided into five groups of people<60mmHg,60-69mmHg,70-79mmHg,80-89 mmHg and?90 mmhg.finally,787 elderly people were included in the study.Spearman and multiple linear regression were used to analyze the independent influencing factors of diastolic blood pressure in the elderly population,and then cross-tabulation and Cox proportional hazards regression were used to compare all-cause death and the risk of cardiovascular and cerebrovascular death in the elderly population at different diastolic blood pressure grouping levels.Statistical methodsStatistics uses the statistical software SPSS 22 to complete the statistical analysis of this study.The baseline characteristic description of elderly patients when they were enrolled in the group was divided into groups according to different levels of diastolic blood pressure.In the description of baseline data between different groups,if the continuous variables are normally distributed,they are described as mean standard deviation(?ąs);if they are not normally distributed,they are expressed as median and quartile spacing,and the Levene test is used for variance homogeneity test.Normal distribution and homogeneity of variance are satisfied.One-way ANOVA is used for comparison between groups,otherwise kruskal-wails H rank sum test is used.Among them,the classified variables such as drinking,diabetes,hypertension and atrial fibrillation are described as numbers(percentages).The chi-square test of cross-tabulated data is used for inter-group comparison.If the theoretical frequency of counting data is less than 10(for the sake of conservatism),Fisher exact probability method is used.Spearman and multiple linear regression were used to analyze the independent influencing factors of diastolic pressure in the elderly population.Cox proportional hazards regression model were used to compare all-cause death and cardiovascular and cerebrovascular death at different diastolic blood pressure levels during 10-year follow-up.Among them,diastolic blood pressure is grouped according to<60mmHg,60-69mmHg,70-79mmHg,80-89mmHg and?90mmHg.Kaplan-Meier survival function was used to compare the median survival time(months)of the five groups of diastolic blood pressure levels during follow-up,and log-rank test was used for comparison.Normal test and variance homogeneity test takeP>0.05 as the test standard.Other test standards are statistically significantAvith P<0.05.Results1.After single-factor Spearman correlation analysis of diastolic blood pressure and related factors,it is found that diastolic blood pressure of the elderly population is positively correlated with SBP(r=0.514,p=0.000),hemoglobin(r=0.172,P=0.000),heartrate(r=0.078,P=0.029),eGFR(r=0.070,P=0.049),BMI(r=0.149,P=0.000),and age(r=-0.197,P=0.000),pulse pressure(r=-0.094,P=0.008)Diastolic blood pressure is taken as dependent variable,and the factors with P<0.05 and diastolic blood pressure found in Spearman correlation analysis are subjected to multiple linear regression analysis to construct a multiple linear regression model.1.1 taking factors such as age,heart rate,BMI,hemoglobin,eGFR,SBP,etc.P<0.05 as independent variables,multiple linear regression analysis was carried out to build a model.it was found that age,heart rate,BMI,hemoglobin,eGFR,SBP were independent influencing factors of diastolic pressure in the elderly population(all P<0.05).from the b value,the influence of 6 independent variables on diastolic pressure from big to small was age,SBP,BMI,heart rate,hemoglobin,eGFR.1.2 diastolic blood pressure is taken as dependent variable,and the factors with P<0.05 and diastolic blood pressure found in Spearman correlation analysis are analyzed by multiple linear regression to construct multiple linear regression model ii(including pulse pressure and excluding SBP).it is found that age,heart rate and hemoglobin are independent influencing factors of diastolic blood pressure in the elderly population(all P<0.05).from the b value,the influences of the three independent variables on diastolic blood pressure are age,heart rate and hemoglobin from the largest to the smallest.2.Overall population2.1 Chi-square test found that 32(45.7%),73(31.7%),73(24.6%),37(26.5%)and 5(12.8%)patients died of diastolic blood pressure in groups of<60mmHg,60-69mmHg,70-79mmHg,80-89mmHg and?90mmHg,respectively.The overall all-cause mortality showed a downward trend with the increase of diastolic blood pressure,with statistical difference(P=0.001).2.2 Kaplan-Meier survival function and log-rank test were used to compare the 10-year survival prognosis.It was found that the middle 10-year survival time of the five groups in diastolic pressure group basically increased with the increase of diastolic pressure,but decreased slightly in 80-89mmHg group(136.9 VS 152.3 VS 160.7 VS 156.4 VS 167.2 months).It is suggested that the survival prognosis improves with the increase of diastolic blood pressure level.The diastolic blood pressure group<60mmHg has the worst survival prognosis compared with the other four groups.The survival prognosis of the other groups with higher diastolic blood pressure is relatively better,showing statistical difference(P=0.002)2.3 Cox proportional hazards regression analysis with diastolic blood pressure as independent variable,all-cause death as dependent variable,and diastolic blood pressure<60mmHg group as reference group showed that all-cause death risks were different for different diastolic blood pressure groups,P=0.003.The HR and 95%CI of the other four diastolic blood pressure groups are:60-69mmHg group(HR:0.639,95%CI:0.422-0.968,P=0.035),70-79mmHg group(HR:0.506,95%CI:0.334-0.767,P=0.001),80-89mmHg group(HR:0.503,95%CI 0.311-0.864,P=0.010),?90 mmHg group(HR:0.231,95%CI 0.090-0.593,P=0.002).With the increase of diastolic blood pressure level,the risk of all-cause death decreased,and there were statistical differences among all groups.2.3 taking diastolic blood pressure as independent variable,cardiovascular and cerebrovascular death as dependent variable,and taking diastolic blood pressure<60mmHg group as reference group,Cox proportional hazard regression analysis shows that HR and 95%CI of the four groups of diastolic blood pressure groups are:60-69mmHg group(HR:0.646,95%ci:0.199-2.100,P=0.468),70-79mmHg group(HR:0.620,95%CI:0.197-1.948,P=0.413),80-89mmHg group(HR:0.978,95%CI:0.301-3.177,P=0.971),?90 mmhg group(HR:0.749,95%CI:0.137-4.090,P=0.739),the risk of cardiovascular and cerebrovascular death is lower in 70-79 mmHg,but there is no statistical difference(P>0.05).3.Hypertension population3.1 taking diastolic blood pressure as independent variable,all-cause death as dependent variable,and diastolic blood pressure<60mmHg group as reference group,Cox proportional hazard regression analysis showed that HR and 95%CI of the other four groups of diastolic blood pressure groups were 60-69mmHg group(HR:1.379,95%CI:0.768-2.475,P=0.281),70-79mmHg group(HR:1.149,95%CI:0.646-2.042,P=0.637),80-89mmHg group(HR:1.136,95%CI:0.614-2.102,P=0.684),and ? 90 mmhg group(HR:1.875,95%CI:0.867-4.054,P=0.110).Compared with<60mmHg group,with the increase of diastolic blood pressure level,the risk of all-cause death increased,and there was no statistical difference between the groups.3.2 taking diastolic blood pressure as independent variable,cardiovascular and cerebrovascular death as dependent variable,and taking diastolic blood pressure<60mmHg group as reference group,Cox proportional hazard regression analysis shows that HR and 95%CI of the four groups of diastolic blood pressure groups are:60-69mmHg group(HR:1.265,95%CI:0.353-4.535,P=0.718),70-79mmHg group(HR:0.799,95%CI:0.220-2.904,P=0.733),80-89mmHg group(HR:0.588,95%CI:0.132-2.628,P=0.487),? 90 mmhg group(HR:0.710,95%CI:0.074-6.826,P=0.767),the risk of cardiovascular and cerebrovascular death is lower in 80-89mmHg group,but there is no statistical significance.4.Coronary heart disease population4.1 With diastolic blood pressure as independent variable,all-cause death as dependent variable,and diastolic blood pressure<60mmHg group as reference group,Cox proportional hazard regression analysis showed that HR and 95%CI of the other four groups of diastolic blood pressure groups were:60-69mmHg group(HR:0.711,95%CI:0.446-0.996,P=0.049),70-79mmHg group(HR:0.608,95%CI:0.385-0.959,P=0.032),80-89mmHg group(HR:0.642,95%CI:0.387-0.975,P=0.042),?90mmHg group(HR:0.218,95%CI:0.066-0.720,P=0.012).Compared with<60mmHg group,with the increase of diastolic blood pressure level,the risk of all-cause death decreased,and there were statistical differences among all groups.4.2 taking diastolic blood pressure as independent variable,cardiovascular and cerebrovascular death as dependent variable,and taking diastolic blood pressure<60mmHg group as reference group,Cox proportional hazard regression analysis shows that HR and 95%CI of the four groups of diastolic blood pressure groups are:60-69mmHg group(HR:2.842,95%CI:0.358-22.561,P=0.323),70-79mmHg group(HR:4.285,95%CI:0.535-34.313,P=0.170),80-89mmHg group(HR:6.164,95%CI:0.713-53.311,P=0.098),and?90 mmHg group(HR:0.000,95%CI:0.000-0.000,P=0.982).with the increase of diastolic pressure level,the risk of cardiovascular and cerebrovascular death increases,but there is no statistical significance.5.People with normal systolic blood pressure(120mmHg?SBP?150 mmHg)5.1 Taking diastolic blood pressure as independent variable,all-cause death as dependent variable,and diastolic blood pressure<60mmHg group as reference group,Cox proportional hazard regression analysis shows that HR and 95%CI of the other four groups of diastolic blood pressure groups are:60-69mmHg group(HR:0.826,95%CI:0.434-1.572,P=0.560),70-79mmHg group(HR:0.733,95%CI:0.394-1.365,P=0.328),80-89mmHg group(HR:0.483,95%CI:0.235-0.997,P=0.049),? 90mmHg group(HR:0.402,95%CI:0.113-1.423,P=0.158).Compared with<60mmHg group,with the increase of diastolic blood pressure level,the risk of all-cause death decreased,but there was statistical difference only in 80-89mmHg group.5.2 taking diastolic blood pressure as independent variable,cardiovascular and cerebrovascular death as dependent variable,and taking diastolic blood pressure<60mmHg group as reference group,Cox proportional hazard regression analysis shows that HR and 95%CI of the other four groups of diastolic blood pressure groups are:60-69mmHg group(HR:0.415,95%CI:0.099-1.735,P=0.228),70-79mmHggroup(HR:0.404,95%CI 0.107-1.525,P=0.181),80-89mmHg group(HR:0.495,95%CI:0.118-2.075,P=0.337),and ? 90 mmhg group(HR:0.525,95%CI:0.055-5.052,P=0.577).The risk of cardiovascular and cerebrovascular death is lower in group 71-80,but it is not statistically significant.6.The elderly population(65-80year)6.1 Cox proportional hazard regression analysis with diastolic blood pressure as independent variable,all-cause death as dependent variable and diastolic blood pressure<60mmHg group as reference group showed that HR and 95%CI of the other four groups of diastolic blood pressure groups were 60-69mmHg group(HR:0.561,95%CI:0.300-1.049,P=0.070),70-79mmHg group(HR:0.443,95%CI:0.239-0.821,P=0.010),80-89mmHg group(HR:0.571,95%CI:0.297-1.099,P=0.094),?90mmHg group(HR:0.292,95%CI:0.096-0.888,P=0.030).Compared with<60mmHg group,the risk of all-cause death decreases with the increase of diastolic blood pressure level,but there is only a statistical difference between 70-79mmHg group and?90mmHg group.6.2 taking diastolic blood pressure as independent variable,cardiovascular and cerebrovascular death as dependent variable,and taking diastolic blood pressure<60mmHg group as reference group,Cox proportional hazard regression analysis showed that HR and 95%CI of the other four groups of diastolic blood pressure groups were 60-69mmHg group(HR:0.996,95%CI:0.111-8.914,P=0.997),70-79mmHggroup(HR:0.536,95%CI 0.056-5.154,P=0.589),80-89mmHg group(HR:2.292,95%CI:0.282-18.635,P=0.438),and ?90 mmHg group(HR:2.049,95%CI:0.186-22.608,P=0.558).The risk of cardiovascular and cerebrovascular death is lower in group 70-79,but it is not statistically significant.7.The elderly population(>80year)7.1 Cox proportional hazard regression analysis with diastolic blood pressure as independent variable,all-cause death as dependent variable and diastolic blood pressure<60mmHg group as reference group showed that HR and 95%CI of the other four groups of diastolic blood pressure groups were 60-69mmHg group(HR:0.798,95%CI:0.457-1.392,P=0.426),70-79mmHg group(HR:0.743,95%CI:0.423-1.306,P=0.303),80-89mmHg group(HR:0.708,95%CI:0.357-1.407,P=0.325),and ? 90 mmhg group(HR:0.216,95%CI:0.029-1.619,P=0.136).Compared with<60mmHg group,with the increase of diastolic blood pressure,the risk of all-cause death decreased,but there was no statistical difference.7.2 taking diastolic blood pressure as independent variable,cardiovascular and cerebrovascular death as dependent variable,and taking diastolic blood pressure<60mmHg group as reference group,Cox proportional hazard regression analysis showed that HR and 95%CI of the other four groups of diastolic blood pressure groups were 60-69mmHg group(HR:0.996,95%CI:0.111-8.914,P=0.997),70-79mmHggroup(HR:0.536,95%CI 0.056-5.154,P=0.589),80-89mmHg group(HR:2.292,95%CI:0.282-18.635,P=0.438),and?90 mmhg group(HR:2.049,95%CI:0.186-22.608,P=0.558).The risk of cardiovascular and cerebrovascular death is lower in group 70-79,but it is not statistically significant.Conclusion1.Age,heart rate,BMI,hemoglobin,eGFR,SBP are independent influencing factors of diastolic pressure in the elderly population.2.among the five groups of elderly patients with diastolic blood pressure,compared with the group with diastolic blood pressure<60mmHg,the risk of all-cause death decreases with the increase of diastolic blood pressure.3.Diastolic pressure<60mmHg in elderly patients with coronary heart disease is due to increased risk of death. |
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