| Objective:To describe the distribution of carotid atherosclerosis progression in the middle-aged and elderly general populations in China and to evaluate the determinants of the carotid atherosclerosis progression and to explore the association between the progression of carotid atherosclerosis with cardiovascular diseases and its potential value in cardiovascular risk assessment and prevention therarpies.Methods:We prospective studied 999 from 1202 rural residents from Shijingshan district,in Beijng in the USA-People's Republic of China(PRC)Collaborative Study of Cardiovascular and Cardiopulmonary Epidemioiogy(the USA-PRC Study) cohort,whose age range was from 42 to 73 years.Cardiovascular risk factors and carotid ultrasound examinations were measured at baseline(in Sept,2002) and after 3.1±0.1years.To assess carotid atherosclerosis progression in carotid artery bulb and common carotid artery(including proximal and distal segmens),progression rate of carotid IMT,the increments in plaque numbers and areas,the prevalence of novel plaques and the progression rate of plaque areas were calculated according to the difference between baseline value and resurveyed ones in carotid IMT,plaque numbers and plaque areas, respectively.Results:1 Baseline characteristics between the reexamined individuals and not reexamined ones were similar in cardiovascular risk factors.2 Distribution of carotid atherosclerosis progression indicators1) The IMT progression rate:For all participants,the mean(±SD) IMT progression rate was 0.012±0.034 mm/y.There was no difference between males and females (0.011±0.034 mm/y VS0.012±0.033 mm/y,P＞0.05).After adjustment for baseline IMT, higher IMT progression rate was found in subjects aged more than 55 years old than ones aged less than 55 years old.The mean IMT progression rate was 0.014±0.045 mm/y for bulb,0.014±0.040 mm/y for the distal segment and 0.007±0.040 mm/y for the proximal segment.The IMT progression rate was highest in bulb after adjusting for baseline corresponding IMT.There was no difference in IMT progression rate between bilateral carotid arteries segments.2) Plaque:During the 3-year follow up,the prevalence of plaques was increased by 6.7%(from 34.9%to 41.6%,the mean increase in the prevalence of plaques per year of follow up was 2.2%) for all participants and by 6.2%for males and by 7.0%for females, respectively.The greatest increments in plaques numbers was six during follow up whereas the mean increments in plaques numbers was 0.15.It was about 0.05 for mean increments in plaques numbers per year of follow up.The prevalence of novel plaques during follow up was 24.4%(which was 8.1%for the average prevalence of novel plaques per year of follow up) for all participants and 30.3%for males and 21.5%for females, respectively.The progression rate of plaque areas was 2.06 mm~2/y for the total and 2.74 mm~2/y for males and 1.72 mm~2/y for females,respectively.Much more increments of plaques numbers,higher prevalence of novel plaques and progression rate of plaque areas were found in males than in females were found in subjects aged more than 55 years old than in ones aged less than 55 years old,and were found in bulb than in distal and proximal segments.3) The characteristics of carotid atherosclerosis progression among subjects with ICVD:Subjects with ICVD at baseline had higher progression rate of IMT and plaque areas and more increments of plaques numbers,followed by ones with newly diagnosed ICVD during follow up,the least was ones without ICVD at either examination.3 Relationship between indexies of carotid atherosclerosis progression and baseline cardiovascular risk factors1) The increments in IMT during follow up:The higher in quartile level of baseline SBP,PP and fasting blood glucose,the more in increments in IMT during follow up. Current smokers at baseline had more increments in IMT,followed by ever smokers. Partial correlation analysis,after adjusting for baseline IMT,showed the increments in IMT was associated with age,SBP,PP.Multivariate linear regression analysis showed that baseline age and SBP were determinants of the increments in IMT for males.And no association was found between baseline risk factors and the increments in IMT among males. 2) The increments in plaques numbers during follow up:With the increase in quartile level of baseline SBP,PP,TG and fasting blood glucose,the increments in plaques numbers during follow up was increased for all participants.Current smokers at baseline had the most increments,followed by ever smokes.After adjustment for baseline plaques numbers,partial correlation analysis showed that the increments in IMT was positively associated with age and SBP,PP,TC and FBG and negatively associated with HDL-C. Multivariate linear regression analysis showed that baseline age,current smoking,fasting blood glucose,HDL-C were the determinants of the increments in plaques numbers.There was difference in the association of the increments in plaques numbers with baseline risk factors.3) The risk of novel plaques formation:Multivariate logistic regression analysis showed that the higher risk for novel plaques formation was associated with baseline age, current smoking,hypertension,diabetes mellitus for males and with baseline age,current smoking,higher TC and HDL-C for females.4) The increments in plaque areas during follow up:Current smokers at baseline had grearter increments in plaque areas,followed by ever smokers.With decrease in quartile level of HDL-C and the increase in quartile level of TG,the increments in plaques areas during follow up was increased for all participants.After adjustment for baseline plaques areas,partial correlation analysis showed that the increments in plaques areas during follow up was positively associated with age and SBP,PP,and TG. Multivariate linear regression analysis showed that the increments in plaques numbers was associated with baseline age,current smoking,hypertension,and diabetes mellitus for males and with age and current smoking for females.5) With the increase in baseline ICVD 10-year risk scores,there was increase in the increments in IMT and plaque areas and the prevalence of novel plaques during follow up. The linear trend was similar to the association of estimation of 10-year risk of ICVD.Conclusions:The epidemiologic characteristics of carotid atherosclerosis progression in our middle-aged and elderly population(age range,42 to 73 years old) in China including the followings:1) Carotid atherosclerosis progression profiles:Mean increments in IMT per year of follow up was 0.012mm.Mean novel plaque numbers and prevalence per year of follow up were 0.05 and 8.1 percent,respectively.And mean increase in plaque areas per year of follow up was 2.06 mm~2.2) The distribution characteristics:There was no sex-specific difference in IMT progression rate.Much more in the increments in plaque numbers and areas were found in males than females and were found in subjects aged more than 55 years old than in ones aged less than 55 years old,and were found in bulb than in distal and proximal segments, and were found in ones with ICVD and than ones without.3) Baseline age and SBP were the determinants of IMT progression and baseline age,current smoking,hypertension,diabetes mellitus,higher TC and lower HDL-C were associated with plaque progression,and age,current smoking were the two strongest risk factors.In addition,our ICVD 10-year risk scores were associated with IMT and plaque progression.Prospective data on IMT and plaque progression and incident cardiovascular events are required to establish the true value of progression data as a surrogate measure of cardiovascular risk.
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