Temporal trends in Prevalence, Awareness, Treatment, and Control of Hypertension from 2000 to 2010 in Chengdu, China

This study aimed to describe trends in prevalence, awareness, treatment, and control in hypertension in Chengdu from 2000 to 2010. Two community-based cross sectional surveys were conducted among those aged 40–79 years in 2000 (n = 4850) and 2010 (n = 5456). Demographic characteristics, blood pressure (BP) and associated risk factors were examined. Mean systolic and diastolic BP increased from 117.8 ± 33.9 to 132.1 ± 21.2 mmHg (P < 0.001), and 75.3 ± 19.1 to 79.3 ± 11.2 mmHg (P < 0.001) over past decade, respectively. The prevalence of hypertension increased from 27.7 to 29.4% (P < 0.001). Awareness increased from 37.7 to 42.5% (P < 0.001). The overall treatment rate increased from 20.9 to 28.0% (P < 0.0001), while among subjects aware of hypertension, treatment increased from 46.9 to 65.8% (P < 0.001). In hypertensives, control increased from 6.8 to 6.9% (P = 0.6684). Nevertheless, in hypertensives aware and treated, control decreased from 32.5 to 24.3% (P = 0.020). Hypertension prevalence increased in the last decade, while awareness, treatment and control remained considerably low in Chengdu.

in 2010. Current smokers decreased over the past ten years (P < 0.001). And participants with DM increased sharply (P < 0.001). Mean BMI increased nearly 4 units in past ten years (P < 0.001). And the prevalence of being overweight increased more than 6% (P < 0.001). Moreover, the prevalence of being obese doubled over time (P < 0.001). Mean levels of total cholesterol(TC), low-density lipoprotein cholesterol(LDL), triglycerides(TG) and fasting plasma glucose (FPG) increased in 2010 compared with those in 2000 (All P < 0.001).
Trends in BP over ten years. Both mean SBP and DBP increased over ten years (All P < 0.001).
The mean levels of SBP/DBP were 117. 8  levels of SBP and DBP were higher in 2010 than it in 2000 by age and sex (All P < 0.001). In both years, there was a trend that the levels of SBP and DBP were increasing with age (All P for trend < 0.05, Figs 1 and 2). Moreover, mean level of SBP in women aged 60 years and older was higher than that in men in both years. The highest DBP level in men was in the 50-59 year age group in both years, while in women, the highest DBP level was in the 70-79 year age group in 2000 and in the 60-69 year age group in 2010 (Figs 1 and 2).
Trends in prevalence of hypertension and subtypes. The overall age-standardized prevalence of hypertension has increased nearly 2% in this population over past 10 years (P < 0.001, Table 3). The overall prevalence of hypertension was significantly higher in men than that in women (30.2% vs 23.4% in 2000, P < 0.001, and 31.0% vs 27.8% in 2010, P = 0.022, Table 3). In both surveys, the overall hypertension prevalence increased with age (Both P for trend < 0.001). In both surveys, the highest hypertension prevalence was among subjects aged 70 years and older. The overall prevalence of pre-hypertension increased about 2% in past 10 years as well (P < 0.001, Table 3). It was different from hypertension that the prevalence was decreasing with age in both surveys (Both P for trend < 0.001). And the overall pre-hypertension prevalence was higher among men than women (35.3% vs 32.7% in 2000, P = 0.059, 41.7% vs 33.0% in 2010, P < 0.001, Table 3). In 2010, the highest pre-hypertension prevalence was in subjects aged 50-59 years, compared subjects aged 60-69 years in survey 2000.
The overall prevalence of isolated systolic hypertension (ISH) in 2010 was double that of the 2000 ( Table 3). The overall ISH prevalence increased with age in both surveys. Moreover, in subjects aged 60 years and older, the ISH prevalence increased sharply significantly.
The overall prevalence of IDH in 2010 decreased almost 40% compared with that in 2000 (P < 0.001). In both surveys, there was a trend that the prevalence decreased with age. Moreover, the prevalence was the highest among subjects aged 40-49 years in both years and the prevalence in each age group in 2000 was higher than that in 2010 ( Table 3).
The overall prevalence of SDH increased about 4% in past decade (10.8% in 2000 vs 14.9% in 2010, P < 0.001). In both surveys, the SDH prevalence increased with age and the prevalence of SDH was higher for men than women in each age group (Table 3).
Changes in constituent ratio. In 2000, the prevalence of IDH and SDH were higher than that of ISH.
However, the prevalence of ISH and SDH were much higher than that of IDH in 2010 (All P < 0.001, Fig. 3). Over past 10 years, the prevalence of ISH and SDH increased while IDH prevalence decreased (All P < 0.001).
Trends in awareness, treatment and control of hypertension. The overall awareness slightly increased from 37.7% in 2000 to 42.5% in 2010 (P < 0.001). This descent was present in both sexes, and especially noticeable in women (Table 4). While awareness of hypertension was higher among women compared with men. The overall treatment prevalence in overall community population increased nearly 8% over past ten years (P < 0.001). The increase was larger in women than in men.  Among those who were aware their hypertension, the treatment rose from 46.9% (in 2000) to 65.8% (in 2010) significantly (P < 0.001, Table 4). Among overall population who were aware of hypertension, treatment was higher in women than that in men in 2010, while it was lower in 2000. However, the increases of treatment rate among those aware was higher in women than it in men (men: 16.3%, women: 21.9%). Overall control increased only 0.1% with no significance (6.8% to 6.9%, P = 0.668) over the past ten years. Among treated hypertensives, control (BP < 140/90 mmHg) was 32.5% in 2000, compare to 24.3% in 2010 (P = 0.020, Table 2). Control was also higher in women than in men in both years. Moreover, there was more decreasing of control in men than in women (decreases for men vs women = 8.5% vs 7.8%).

Discussion
The main findings of this study are as follows: among Chengdu residents aged 40 to 79 years, 1). SBP and DBP levels increase over past decade, 2) prevalence of hypertension and pre hypertension increase steadily with slowly increasing awareness, while treatment and control remain considerably low.
There were more women in survey 2010, mainly because many younger and middle aged men moved to work in more developed east coastal areas (i.e. Guangdong, Fujian, Zhejiang provinces) over past decade. The steadily increased BP level and prevalence may be related to lifestyle changes accompanying with industrialization and urbanization, such as high salt food 6 , rich fat food intake (Sichuan cuisine is characterized by pungent, hot, and salty flavors), and higher BMI 7 . Smoking 8,9 and work related stress are associated with hypertension development 10 . Accompanying with the industrialization and urbanization, increased stressful workload may involve in the hypertension prevalence increasing. Limited knowledge of hypertension prevention, diagnosis treatment and its relevant risk factors among community physicians and general population may contribute to the low awareness. Treatment of hypertension was improved with economic development in past decade, especially apparently among those were aware of their hypertension. Higher socioeconomic status could positively improve the awareness and control of hypertension, and people would also have a better compliance of medicine treatment. Accompanying with the rapid economic development of Sichuan, people changed their dietary habits with more unhealthy fatty and salty food, while tended to be more dependent on morden transportation daily. Meanwhile, more people gradually became to care more about their health and generally could relatively afford the disease cost during past decade. It could be one reason for the increasing hypertension prevalence accompanying by  increasing awareness and treatment. While during past decade, no apparent control improvement in smoking and drinking, increasing overweight and obesity, and increasing lipid and glucose levels could interact and potentially contribute to the poor hypertension control. Besides, poor compliance with medication and lack of health eduction could also be important reasons for poor BP control. During past decade, there was no increasing trend of SBP and DBP levels in America 11, 12 during the past two decades and in Japan 13 , while there was a consistent decreasing of BP in Germany 14 , Spain 15 , Italy 16 and Korean 17 . From 1988 to 2008, there was an increasing trend of hypertension prevalence in Americans aged 40 years and older 11 , however, the prevalence of hypertension in Japan 13 , Germany 14 , Italy 16 and Korea 17 decreased. Other Chinese studies in other areas [18][19][20] also have found that there is an increasing trend of prehypertension and hypertension prevalence. A recent study in Chongqing 20 , which is a neighbor city of Sichuan with similar geographic, culture, and dietary background, reported that hypertension prevalence in local adults (23.4% in 2012 and 12.0% in 2002) doubled during past decade. The increasing trend of hypertension prevalence in our study is in accordance with studies in other Chinese cities, especially cities with similar background, and other developing countries, such as India 21 and Thailand 22 . During the same period, the hypertension awareness and treatment in America 11, 12 , Germany 14 and Korean 17 increased substantially, which contributed to a better BP control. And awareness of hypertension in other areas in China tended to increase consistently [18][19][20] . Nevertheless the treatment in Chengdu is unluckily lower than in Shandong 18 , Beijing 19 , while higher than in Chongqing 20 , India 21 and Thailand 22 . In past decade, the hypertension control doubled in Germany 14 , Spain 15 and nearly doubled in America 11 and it increased steadily in developed couriers, such as Italy 16 and Korean 17 . Unfortunately, the hypertension control in Chengdu was low, which was in accordance with studies in other Chinese cities 5,[18][19][20] . It is apparently that improvements in hypertension awareness, treatment contributed to better control in european countries 11,12,[14][15][16] .
Lifestyle modification contributing to BP decrease is recommend to general population in Chengdu. People should increase their physical activity, improve levels of fruit and vegetable intake, consume less fatty diet and quit smoking. A better community based primary health care and primary prevention system focused on early diagnosis and treatment, patients management, hypertension knowledge education and lifestyle risk factors modification in general population is needed for better BP control.
This study has following limitations. First, results of this study should be interpreted with caution, since both surveys only focused on population in Chengdu, although main results are comparable to studies in other Chinese cities. Second, the gender constituents in two separate surveys were different and quantity of physical activity was not measured in 2000. Third, due to the different economical support by the government, the methods for diabetes mellitus diagnoses were different in both surveys. Fourth, smoking and alcohol consumption data are based on self-report with the possibility of misclassification of exposure.   In conclusion, hypertension prevalence increased steadily among residents aged 40 to 79 years in Chengdu from 2000 to 2010, while awareness, treatment and control remained considerably low. More efforts should be taken to improve hypertension awareness, treatment and control among middle aged and older residents. Future enhanced public health care program focused on these problems is needed.

Materials and Methods
Population. Two cross-sectional surveys were conducted from 1998 to 2000 and from 2008 to 2010 separately in communities of Chengdu, using a multistage cluster sampling. The study population included 4850 and 5456 subjects aged 40-79 years (All subjects were Han ethnicity) living in Chengdu more than 3 years in survey 2000 and survey 2010, respectively. The response rates for the subjects participating in the surveys of 1999 and 2009 were 95.1% and 95.4%, respectively. Ethics approval was obtained from the Ethics Committee of the Second People's Hospital of Chengdu, China. The methods in the study were in accordance with relevant guidelines and the Declaration of Helsinki. All participants gave informed consent.
Data collection. Data were collected through a standard household questionnaire interview with additional interviewing and a physical examination in community hospitals in both 2000 and 2010, separately. In both years, all researchers were trained for questionnaire administration, correct cuff size selecting, BP measurement and other techniques needed in surveys with standard techniques. The information collection included demographic characteristics, smoking, alcohol consumption, history of hypertension, cardiovascular disease, diabetes, and administration of antihypertensive medication, physical examination, waist circumference, body weight, and height. In both years, participants had their blood pressure (BP) measurements with a validated mercury sphygmomanometer by trained researchers. Three consecutive BP readings were taken on the right arm with an appropriate cuff size (22 to 26 cm long and 12 to 14 cm wide), in a sitting position after a 10 minutes rest. Participants were not allowed to smoke cigarettes, drink tea/coffee, or do physical exercise half an hour before BP measurements. The room temperature was required to be between 18 °C and 25 °C for measurements. Overnight fasting blood specimens of participants were collected and tested in the central laboratory of our hospital in both years. The oral glucose tolerance test (OGTT) was tested in all subjects in 2010, while not in 2000.
Awareness of hypertension was determined by definite response to question "Have you ever been told that your blood pressure was high or you had a hypertension" by a physician/heath care. Treatment of hypertension was confirmed by saying "yes" to this question, "Are you taking antihypertension medication during last three months, because of your high BP/hypertension?", Control of hypertension was defined as the measured SBP < 140 mmHg and DBP < 90 mmHg in patients with hypertension under antihypertension treatment 23,24 .
Body mass index (BMI) was defined as weight (kg)/height (m 2 ). Overweight was define as 25 kg/m 2 ≤ BMI < 28 kg/m 2 . Individuals with a BMI of 30 kg/m 2 or greater are defined as obese.
Statistical analysis. Participants were subdivided into 4 age groups: 40 to 49, 50 to 59, 60 to 69, and 70 to 79 years old. Statistical analysis was performed by using of SPSS17.0 for Windows (Chicago, IL, USA). Continuous variables were expressed by mean ± standard deviation. Categorical variables were expressed by percentage (%). Rate of awareness, treatment and control of hypertension were standardized by the China national census. Comparisons between groups used the Chi -Square Test for categorical variables and one way ANOVA for continuous variables. The Cochran -Mantel -Haenszel test was used to analyze for the trend of prevalence over various age groups. A two-sided P value of < 0.05 was considered to be statistically significant.