Study On The Natural Prognosis Of Normal Blood Pressure In Incident Hypertension And Its Influence Factors

Objectives:At present,most of the researches on the prevalence or incidence rate of hypertension were based on the mean blood pressure values measured on the same day 3 times.However,a large number of clinical studies showed that the risk of false positive hypertension increased based on the mean blood pressure.To evaluate the accuracy of this blood pressure measurement method,we conducted this study based on China Health and Nutrition Survey?CHNS?,all individualized cohort study data.We explored the prognosis of normal blood pressure?Normal BP?in incident hypertension subjects in 2 consecutive surveys and its influence factors,and we also explored the hypertension recurrence rate of normal blood pressure population turning from incident hypertension.Methods:Based on the 1989-2011 survey year data of CHNS,adults aged 18 years old and above were enrolled as subjects.The study was divided into two parts:1)The prognosis of normal blood pressure in incident hypertension population diagnosed at 1991-2009 year was followed up in 2consecutive surveys and the influence factors of incident hypertension turning into normal blood pressure was explored.2)The recurrence rate of hypertension in normal blood pressure population turning from incident hypertension at 1993-2009 year was calculated.And the hypertension incidence rate of population never diagnosed with hypertension in CHNS1989-2011 were also calculated,and we took it as standard to calculated the relative risks?RR?and its 95%confidence interval?95%CI?of hypertension recurrence rate in normal blood pressure population turning from incident hypertension.The incidence rate?IR?of hypertension was standardized by using the sixth national census data of China in 2010.Univariate analysis was carried out on factors influencing incident hypertension turning into normal blood pressure,such as gender,age,BMI,blood pressure severity and subtypes.Cox regression analysis was used to control confounding factors.Statistical analysis:as the measurement data was non-normal distribution,the data was present in the form of median?interquartile range?,and the rank sum test was used for data comparison and analysis.The count data was present in the form of number?percentages?and compared with?² test.The trend test adopted the Linear-by-linear test.The SPSS 21.0 was used for data collation and analysis,and the test standard was?=0.05?bilateral?.Results:1.There were total 3,565 incident hypertension were enrolled in this study.The subjects were followed up for mean 1.86?95%CI,1.82-1.90?years.Incident hypertension turned into normal BP,remained for hypertension?HTN?,and lost to follow up?Lost?were 1,762?49.4%?,1,225?34.4%?and578?16.2%?,respectively.There was no significant difference in the proportion of normal BP turning form incident hypertension population between male and female?P=0.196?.As the increase of age,body mass index?BMI?and baseline blood pressure,the proportion of turning into Normal BP all became less(all P _{for trend}<0.05).The proportion of Normal BP turning from new-onset isolated systolic hypertension?ISH?,isolated diastolic hypertension?IDH?,and systolic-diastolic hypertension?SDH?were 47.8%,56.2%and37.9%,respectively.There were significant differences between prognoses of the three hypertension subtypes,?all P<0.001?.2.Univariate analyses showed that as the decrease of age,BMI and baseline blood pressure,the proportion of turning into Normal BP all became large.Cox regression analysis showed that,as the increase of age,BMI and baseline blood pressure,the risk of incident hypertension remained for hypertension became higher.Taking the lowest level as references,the hazard ratio?HR?of the highest level were 2.26?95%CI,1.85-2.76?,1.29?95%CI,1.07-1.55?and 1.59?95%CI,1.25-2.03?,respectively.The Cox regression analysis of the incident hypertension subtypes showed that,in the IDH population,as the decrease of age and BMI,the probability of turning into normal blood pressure became large.In the incident ISH and SDH population,as the decrease of baseline blood pressure,the probability of turning into blood pressure became large.3.A total of 15,094 subjects in the population never diagnosed with hypertension were followed up for 124,115 person-years?mean 8.22 years?,and the total incidence rate of hypertension was 4.84?95%CI,4.72-4.95?per100 person-years.And total 1,461 subjects in the Normal BP population were followed up for 6,212 person-years?mean 4.25 years?,the total recurrence rate of hypertension was 9.24?95%CI,8.52-9.96?per 100 person-years.Compared with the population who were never diagnosed with hypertension,the risk of recurrent hypertension increased in Normal BP population turning from incident hypertension,total relative risk?RR?was 1.91?95%CI,1.75-2.08?.Conclusions:1.The proportion of the overall incident hypertensive population turning into normal blood pressure was 49.4%.The highest proportion of normal blood pressure turning from new-onset IDH population was 56.2%.The lowest was 37.9%turning from new-onset SDH population.2.In the IDH population,as the decrease of age and BMI,the probability of turning into normal blood pressure became large.In the incident ISH and SDH population,as the decrease of baseline blood pressure,the probability of turning into blood pressure became large.3.Compared with the population who were never diagnosed with hypertension,the risk of recurrent hypertension increased among normal blood pressure population turning from incident hypertension,total relative risk was 1.91?95%CI,1.75-2.08?.