| Objective:The morbidity and mortality of cardiovascular diseases in China has been increasing,and the mortality rate is the highest among various diseases,which leads to a huge medical expenses and disease burdens.Hence,prevention and treatment of cardiovascular diseases were imminent.Increased blood pressure has been convinced to be one of the clear causes of cardiovascular diseases;however,whether long-term variability of blood pressure has effect on the risk of cardiovascular diseases was currently inconclusive.This study aimed to explore the impact of long-term variability of blood pressure on the risk of cardiovascular diseases,and to find the influencing factors of blood pressure variability,so as to provide a theoretical reference for the prevention and intervention of cardiovascular disease.Methods:An ambispective cohort study was designed and conducted from Jan.2010to Sep.2019.Two community health service centers in Tianjin was randomly selected as the research field.Residents aged over 50 years old who performed health examinations in these two community health service centers from April to May 2017and met the inclusion criteria were invited to attend this research.Physical examination data,especially the data on blood pressure,of all study subjects were retrospectively collected from January 2010 to May 2017.Then,the participants were followed up till September 2019 to observe the occurrence of new cardiovascular diseases throughout the study period.Long-term blood pressure variability was assessed using standard deviation（SD）,coefficient of variation（CV）,average successive variability（ASV）,and average real variability（ARV）of systolic blood pressure（SBP）and diastolic blood pressure（DBP）for each subject throughout the study period.The Kaplan-Meier method Log-rank test was used to compare the survival curves and median survival of the two groups with high and low blood pressure variability（divided by the median）.Cox Proportional risk regression model analysis was applied to explore the relationship between eight indicators reflecting blood pressure variability and the incidence of cardiovascular diseases,and ratio（HR）and its 95%confidence interval were calculated before and after adjustment for potential confounders.The indicator with the largest area under the curve was selected according to the ROC curve to found cutoff values.All participants were classified as high blood pressure variability according to the cutoff values（at least one of the systolic and diastolic pressure variability indicators were greater than its cutoff values）or low variability（both systolic and diastolic pressure variability indicators were less than its cutoff values）.Binary logistic regression was used to explore the influencing factors of blood pressure variability,and odds ratio（OR）and its 95%confidence interval were calculated.Result:（1）A total of 1275 eligible participants（508 males and 767 females）were included in the study.The baseline（the time recruited into the cohort）age was 64.6±6.6 years,and the median follow-up time was 2814 days（7.7 years）.During the whole follow-up period,a total of 412 developed new cardiovascular disease,with the cumulative incidence rate of 32.3%.185（36.4%）males and 227（29.6%）females.The rate in men was higher than that in women（36.4%vs 29.6%,P=0.011）.（2）The incidence of cardiovascular disease was compared with respect to the characteristics of the participants.The results showed that the incidence of cardiovascular diseases increased with the increase of age,education level,BMI,waist circumference,and baseline SBP levels;Incidence rate was also higher among those with hypertension or having less physical exercises compared to their counterparts.No significant association was found of cardiovascular diseases with smoking,drinking,family history of cardiovascular disease,and the antihypertensive medication.（3）Incidence Incidences of cardiovascular diseases in each quartile of blood pressure variability was calculated,which were 18%-20%in the lowest quartile,and 60%in the highest quartile,indicating that with the increased of blood pressure variability,the incidence of cardiovascular disease also increased(all Ptrend<0.05,except for SBP＿SD)（4）High and low blood pressure variability was categorized according to the median of the eight indicators,and the cardiovascular disease survival curves of the two groups were compared.It was found that except for SBP＿SD,the survival rate of those with higher blood pressure variability was higher than those with lower variability.（5）COX proportional hazards regression analysis using blood pressure variability as continuous independent variables and cardiovascular disease as the dependent variable found that there were significant correlation between SBP＿CV,SBP＿ASV,SBP＿ARV,DBP＿SD,DBP＿CV,DBP＿ASV,DBP＿ARV are significantly correlated with the cardiovascular disease.The correlation before and after adjustment is statistically significant.The adjusted HR value and its 95%CI are 2.063（1.924,2.212）,1.370（1.326,1.416）,1.080（1.065,1.095）,2.121（1.968,2.285）,2.007（1.876,2.146）,1.691（1.597,1.790）,1.116（1.092,1.142）.SBP＿SD was not found to be associated with cardiovascular disease.Its adjusted HR（95%CI）was 0.943（0.807,1.103）,P=0.464.The HR associated with SBP variability and cardiovascular disease is generally higher in people with a history of hypertension than those without a history of hypertension except SBP＿SD.For diastolic blood pressure,the HR associated with DBP variability and cardiovascular disease is generally higher in people without a history of hypertension than those with a history of hypertension.（6）Multivariate binary logistic regression analysis showed that age,family history of cardiovascular disease,history of hypertension,waist circumference,baseline SBP and DBP levels were significantly correlated with blood pressure variability（P<0.05）.Conclusion:（1）The long-term variability of systolic or diastolic blood pressure would increase the risk of new cardiovascular diseases,and SBP＿ASV and DBP＿SD had high predictive value.（2）In addition to blood pressure variability,gender,age,education level,exercise,history of hypertension,BMI,waist circumference,and baseline systolic blood pressure levels were associated with cardiovascular disease（3）In people with a history of hypertension,SBP variability had a higher predictive value for cardiovascular disease,and diastolic blood pressure variability had a higher predictive value in people without a history of hypertension.（4）Elder,large waist circumference,high baseline blood pressure levels,a family history of cardiovascular disease and a history of hypertension were related to higher risk of high blood pressure variability. |
