| Objective :Cardiovascular disease (CVD)has become one of the leading killers that threats to human life and health at present. Hypertension is an important risk factor of coronary heart disease(CHD) and stroke. Control of blood pressure has significantly reduce the risk of cardiovascular disease.It had been suggested in many epidemiological studies that improving the quality of antihypertension could make more benefit to hypertensive patients,and blood pressure variability control was an important way of improving the quality of antihypertension.The aim of this study was to provide clinical evidence for improving the quality of antihypertension by determining the blood pressure variability(including morning blood pressure surge(MBPS)and circadian rhythm).1. To investigate the prevalence of morning peak and circadian rhythm by cross-sectional study in elderly people of Guangzhou Military.2. To study the status and risk factors of MBPS in the elderly hypertensive patients.3. To study the status and risk factors of circadian rhythm blood pressure in the elderly hypertensive patients. Subjects and Methods:1.subjects:The present study was based on 827 middle and old aged people (mean age 76 years,782 men and 45 women) who were finally enrolled into the study underwent health screening in Guangzhou military region between June 2009 and December 2010. There were 659 people aged 65y or more, and 558 were hypertension patients.2. Methods: All subjects were admitted to the health screening research through the questionnaire survey, physical examination and ambulatory blood pressure monitoring(ABPM). General information, physical examination, laboratory tests and clinic blood pressure measurements as well as blood pressure variability index, heart rate variability index and other information were recorded.3. The morning BP surge (MBPS) was calculated as follows: mean systolic BP during the 2 hours after awakening minus mean systolic BP during the 1 hour that included the lowest sleep BP. The subjects were divided into the MBPS group (≥35 mmHg) and the non- MBPS (<35mmHg) group based on MBPS.Circadian blood pressure profile was divided into dippers, nondippers, inverse dippers and extreme dippers based on the reduction in the average SBP during the night period.4.Statistical analysis: A database was created by SPSS 17.0 after quality examination of data.Continuous variables were reported as mean±SD and analyzed by t test or analysis of variance;categorical variables were reported as sample rate and compared using the chi-square or Fisher′s exact test;Risk factors of orthostatic hypotension were studied by unconditioned Logistic regression analysis; Multivariate logistic regression analyses were used to determine the relationship between orthostatic hypotension and cardiovascular and cerebrovascular diseases. A p-value of less than 0.05 was considered significant.Results:1. The condition of the total patients: 827 persons (782 males) were enrolled in the study; There were 168 patients aged less than 65(mean age 54.77±5.60),216 aged between 65-79y (mean age 75.38±4.24), as well as 443 agd 80y or more (mean age 83.92±3.28). 1.1 The current status of morning blood surge1.1.1 All the people were divided into hypertensive group (HPG) and non-hypertensive group(NHPG) and significant differences could be observed in the prevalence and amplitude of MBPS between the two groups(18.1%vs 7.2%,22.39±13.60mmHgvs 19.35±10.56 mmHg).1.1.2 The prevalence and amplitude of MBPS in the elderly hypertensives were significantly higher than than in the very elderly(19.9%vs6.8%; 22.89±13.91 vs 19.24±10.97).1.2 The current status of circadian rhythms in elderly hypertensive patients: significant difference could be found in the prevalence of abnormal circadian rhythms and the rate of nighttime blood pressure drop (86.9% vs 77.3%, 1.54±8.18vs5.47±6.67).1.3 Among the total study participants (n=558) at the baseline,there were 111 people with morning blood surge(19.9%)and 485 people with abnormal blood pressure circadian rhythms(86.9%). Following the criterion of"<140/90mmHg",all the hypertensive patients were divided into BP standard group and BP atypia group,but no significant differences in the prevalence of MBPS and abnormal BP circadian rhythms could be detected between the two groups(19.3%vs23.9%;87.5%vs83.1%).2. In a boundary point of 35mmHg,people were divided into MS group(≥35mmHg)and non-MS group(<35mmHg).2.1 The fasting plasma glucose in MS group was higher than in non-MS group (5.92±1.68 mmol/L vs 5.58±1.18 mmol/L); but the correlation between the MBPS and fasting plasma glucose was not significant after unconditional logistic regression.2.2 Indexes of blood pressure variability (SD of 24h SBP/DBP,SD of DSBP/DDBP,SD of NSBP/NDBP)were significantly higher in the MS group than in the non-MS group,while there were no significant differences in indexes of heart rate variability(SDNN,SDANN,RMSSD,PNN50) between the two groups. After adjustment for known covariables ,24-h PP(OR:1.158,95% CI:1.043-1.286,P=0.006),rate of nighttime blood pressure drop(OR:1.121,95% CI:1.076-1.169, P=0.000),24-h BPV(OR:1.484,95% CI:1.354-1.627,P=0.000)were independently associated with the MBPS.2.3 The prevalence of use of diuretic and three or more antihypertensives was significantly higher in MS group than non-MS group(26.5% vs 16.6%,32.4% vs 23.0%);After logistic regression,use of diuretic was related to MBPS(OR:0.508,95% CI:0.280-0.921,P=0.026).3. According to the rate of NBP decline,the elderly hypertensive patients were divided into normal rhythm group (n=93) and abnormal rhythm group (n=553).3.1 The prevalence of stroke,CHD,Pathoglycemia and Dyslipidemia in abnormal rhythm group with and without MS had no significant difference.(34.5%vs26.1%,74.7%vs68.1%,49.4%vs42.7%,62.1%vs55.3%);3.2 There were significant differences in the indexes of HRV(SDNN,SDANN) and BPV(SD of 24h SBP)between the two groups (113.55±37.58 vs 127.32±29.05, 102.44±51.75 vs118.01±58.57; 11.30±3.12 vs 2.11±3.53);3.3 The prevalence of use of diuretic was significantly higher in normal rhythm group than in abnormal rhythm group (19.2%vs 18.1%);No significant differences were found between all kinds of antihypertensives and circadian rhythms BP.3.4 Risk factors circadian rhythm: Nonconditional logistic regression analysis revealed that 24-hSBP(OR:0.557,95% CI:0.345-0.898,P=0.016),NSBP(OR:0.820,95% CI:0.688-0.978,P=0.027),NSBP (OR:1.889,95% CI:1.139-3.132,P=0.014)and NSPP(OR:1.178,95% CI:1.006-1.379,P=0.042)were independently related to circadian rhythms BP.Conclusions :1. Age is a common risk factor of the MBPS and circadian rhythms; the status of MBPS and abnormal blood pressure circadian rhythms have not been significantly improved after high blood pressure were controlled which suggested BP quality should be further developed.2. The 24h pulse pressure, 24h blood pressure variability, nocturnal blood pressure decline rate are the independent factors of MBPS; Using diuretics may be not beneficial for the control of MBPS. 3. Abnormal blood pressure circadian rhythms is closely associated with heart rate variability, which prompts that elderly patients with abnormal rhythm may accompany serious autonomic dysfunction. The 24h systolic blood pressure, systolic blood pressure of day, systolic blood pressure of night and pulse pressure of night are the independent factors of circadian rhythm. |
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