RISK FACTORS FOR HYPERTENSION IN INDIA AND CHINA: A COMPARATIVE STUDY

Health and Population - Perspectives and Issues 37 (1 & 2), 40-49, 2014 RISK FACTORS FOR HYPERTENSION IN INDIA AND CHINA: A COMPARATIVE STUDY FuJun Wang*, V. K. Tiwari** and Hao Wang*** ABSTRACT To identify the different risk factor for hypertension has differently impacted in India and China. A systematic review focusing on the seven independent variables was conducted. All published studies conducted in India and China with study sample of at least 130 adult population living in urban and rural areas and describing the prevalence and risk factors (age and sex, unhealthy diet, overweight and obesity, alcohol, physical inactivity, tobacco) of hypertension in India and China were included for this review. A total of 60 relevant articles which were extracted, 36 articles met the inclusion criteria. Through analyse the risk factors for hypertension, the review shows China has faced more challenges than India. This has been found that the per capita salt in-take is higher than five grams in both the countries as recommended by the WHO. Key words: Hypertension, Risk-factors, Prevalence of hypertension, In 2013, WHO reported that globally cardio-vascular disease accounts for approximately 17 million deaths a year, nearly one-third of the total deaths for all deaths from diseases. Of these, complications of hypertension account for 9.4 million deaths worldwide every year. Reports indicate that more than one in three of the adults (>=25 years old) has hypertension in 2008, and the prevalence show increase trend in future. China and India are the two largest developing countries and the most populous countries in the world. The prevalence of hypertension shows an increasing trend in both of the countries. Prevention and control of hypertension is a significant challenge. The numbers of the hypertension population in India and China are 118 million and 160 million in 2000 respectively. If the situation of the risk-factors *PGDPHM student, E. mail: wangfujunlxd@163.com; **Professor, Department of Planning and Evaluation; National Institute of Health and Family Welfare, Munirka, New Delhi-110067. *** Director, Tianjin Population and Family Planning Committee, China. 40

for the hypertension is identified in the population, and appropriate action is taken to reduce the adverse-health life styles; the prevalence of hypertension will be effectively controlled. OBJECTIVES The study was done with the following objectives: To review the prevalence of hypertension in China and India, To identify and analyse the risk factors for hypertension in India and China, To compare the risk-factors influencing hypertension in China and India, and To suggest strategies for the control and prevention of hypertension in both the countries. METHODOLOGY This is a review study based on published literatures from India and China. All the published studies conducted in India and China had a study sample of at least 130 young and adult population living in urban and rural areas and describing the prevalence and risk-factors of hypertension in India and China. The studies included age and sex, unhealthy diet, overweight and obesity, alcohol, physical inactivity, tobacco, residence, etc. as risk-factors. A total of 60 relevant articles were collected and out of those, 18 articles met the criteria for inclusion in the current comparison. Studies conducted 20 years ago were not included in this review. The review analysed the influence of the risk-factors for hypertension on India and China as well as it compares data of both of the countries. FINDINGS As we know, the main factors that contribute to the development of high blood pressure include age, sex, unhealthy diet, tobacco use, physical inactivity, harmful use of alcohol, obesity, etc., impact of these main risk-factors were taken into account for the review study. Age and Sex In China, a study showed that hypertension was more prevalent among women than men, and the prevalence rate increased with an increase in age. The study also found that for the age group 35-44 years, men had a slightly higher rate of hypertension than women. However, the result was reverse for the population in the >45 years of age. A cross-section study 1 of China demonstrate that the agespecific prevalence of hypertension was 13.0 per cent, 36.7 per cent, and 56.5 per cent among persons in the age-groups of 20-44 years (young people), 45-64 years (middle-aged people), and 65 years (elderly people), respectively. The 41

observations from the Chinese Registry of Acute Coronary Events describe that the prevalence of high blood pressure increased with an increase in age. In China, the population structure has been gradually changing since 1970. Now, China has more elderly population. China is stepping into an aging population, so preventing hypertension in the elderly group is a challenge (Figures 1 and 2). FIGURE 1 AGE-DISTRIBUTION OF HYPERTENSION AMONG CHINESE FIGURE 2 CHINA s POPULATION PYRAMID 2013 Another research on the trends of hypertension epidemiology in India showed a similar result. High blood pressure (BP) is a major public health problem in India and its prevalence is rapidly increasing among both urban and rural populations 2. It has found that the number of cases increased with an increase in age among 165 study subjects. 10 cases (6.06%) comprising 6 males (6.45%) and 4 females (5.55%) were found in the age group of 21-30 years and 75 cases (45.46%) comprising 35 males (37.63%) and 40 females (55.56%) were in the age group of 51-60 years. 42

FIGURE 3 INDIA s POPULATION PYRAMID 2013 Unhealthy Diet High blood pressure is the leading risk for mortality, globally. Many researches show that excess salt intake affects blood pressure. This conclusion is proved by plenty of scientific experiments and is recognized worldwide. A case control study 2 was conducted in rural township of Tasgaon; Sangli district of Maharashtra in India during 2001-2002, to study the role of certain modifiable riskfactors in essential hypertension in the 21-60 years age group. Among the dietary factors, higher salt consumption was also found to be significantly associated with hypertension (P= 0.0003). Twice the risk of developing hypertension (OR=2.06) was observed among persons consuming more than 5 grams of salt per day. In 2007, a study assessed the salt-intake of 8.5g/day among urban Chennai adults using a food frequency questionnaire 3. In order to determine the relationship between dietary sodium and blood pressure in the Chinese population, several nationwide epidemiological surveys have been conducted to investigate saltintake and the incidence of high blood pressure. The Ministry of Health of China reported that each Chinese person consumes an average of at least 15 grams of salt every day in comparison to five grams as recommended by the WHO. Overweight and Obesity Overweight and obesity are major risk-factors for a number of chronic diseases including hypertension, cardio-vascular diseases and cancer. The risk for hypertension increases with the increase in BMI (Body Mass Index). In 2008, worldwide 35 per cent of adults aged 20 years and over was overweight, and 11 per cent was obese. Another survey conducted among the rural population of Bangalore rural district in India in 2009 showed that about 51.96 per cent was thin with a BMI of <18 while 14.0 per cent was overweight or obese with a BMI measuring >25 and the rest reported normal. Prevalence of hypertension 43

in overweight or obese group was 36 per cent it was 5.8 per cent had a normal BMI 4. A similar research has been conducted in rural area of China in 2004-2006 5 using a multi-stage cluster sampling method to select a representative sample. A total of 45,925 adults aged 35 years or older were examined. The prevalence of overweight and obesity was 16.3 per cent and 1.3 per cent among males respectively, and 24.4 per cent and 2.7 per cent among females (p value for gender differences <0.05). According to the World Health Organization classification, the prevalence rates of overweight and obese were 29.5 per cent and 5.3 per cent respectively. According to a WHO report 6, in 2010, the prevalence rates of BMI in India with >25 among the population aged >15 years are 20.1 per cent males and 18.1 per cent females while these figures stood at 45 per cent males and 32 females in China. Alcohol A study conducted in India 4 showed that alcohol consumption is significantly associated with hypertension. Among the study population, 14 per cent of them had the habit of regular alcohol consumption, out of which more than a third (38.96%) had hypertension. The odds ratio between alcoholics and non-alcoholics was as high as 21. It means that alcohol consumers had 21 times higher risk of hypertension in comparison to the non-alcoholics. Alcohol consumption has been steadily increasing in developing countries like India. At same time, people start drinking at an earlier age than previously. Another research 7 conducted in northern China shows 9151 people out of 32 389 workers developed hypertension during 4 years of follow-up period. At the end of the follow-up, the cumulative incidence of hypertension in relation to daily alcoholic intake of none, 1 24gm, 25 49gm, 50 99gm, 100 149gm and at least 150 gm was 25.03 per cent, 28.82 per cent, 30.10 per cent, 37.07 per cent, 40.14 per cent and 42.49 per cent respectively. According to a WHO report 8, a recent national survey of drinking alcohol in China revealed that China has experienced dramatic increases in the consumption of alcoholic beverages since the 1990s. High-risk drinking behaviour has reached epidemic proportions in China. Physical Inactivity Many studies that showed the relationship between physical inactivity and hypertension were conducted in India. One such study 2 found a statistically significant association between hypertension and leisure time physical inactivity (P=0.009). Odds ratio was found to be 2.51 indicating the absence of leisure time physical activity which is twice the risk of hypertension when compared with positive leisure time physical activity. Some researchers have proved that long-term aerobic exercise regimens have beneficial effects upon systolic blood pressure. 44

A survey 9 related to physical activity level was conducted in China. The results indicate that the proportion of the physically active population in urban China is low. Additionally, a majority of the physical activity that occurs in China is workrelated, and rates of leisure-time physical activity are low, especially in urban settings. With the increasing urbanization taking place in China, rates of physical activity could decline substantially over a relatively short period of time. Tobacco India and China are the two most tobacco consumption countries in the world. Tobacco use is one of the main risk-factors for a number of chronic diseases, including cardio-vascular, cancer, lungs disease, etc. A cohort study lasted for 7 years conducted in rural Kerala, India 10, with a sample of 297 individuals aged 15 64 years who were free of hypertension at the time of study enrolment, were followed-up from 2003 to 2010. Nearly one-quarter (23.6%) of the sample developed hypertension over a mean follow-up period of 7.1 (standard deviation 0.2) years. Current smoking RR value=1.99.the result means that smoking was significantly associated with the incident of hypertension. An earlier study using Meta-analysis method has analyzed 24 reviews about tobacco related with hypertension 11. The result showed a significant difference between them but the link was weak. But some other studies have a different conclusion with no association between smoking and hypertension among the Mongolian population 12. Residence Recent studies 13 using revised criteria (BP»140/90mmHg) have shown a high prevalence of hypertension among urban adults with 30 per cent men and 33 per cent women in Jaipur in 1995, 44 per cent men and 45 per cent women in Mumbai in 1999, 31 per cent men and 36 per cent women in Thiruvananthapuram in 2000, 14 per cent in Chennai in 2001; and 36 per cent men and 37 per cent women in Jaipur in 2002. Among the rural populations, hypertension prevalence rates were found to be 24 per cent in men and 17 per cent in women in Rajasthan in 1994. Hypertension diagnosed by multiple examinations has been reported among 27 per cent of males and 28 per cent of female executives in Mumbai in 2000, and 4.5 per cent of rural subjects in Haryana in 1999. The gap of prevalence rate for hypertension between urban and rural area is very clear in India. According the data from the China National Nutrition and Health Survey 2002 14, the prevalence of hypertension was higher in urban compared with rural areas among men (23% versus 18%; P<0.01) and among women (18% versus 16%; P<0.001). 45

DISCUSSION Data from Inter ASIA, the most recent Chinese national study, estimated that 129824000 Chinese persons aged 35 74 years had hypertension. The prevalence of hypertension in China was 26.0 per cent 15. As per the World Health Statistics 2010 report 16, 33.20 per cent of men and 31.70 per cent of women above 25 years suffer from hypertension in India. However, different levels of risk-factors of hypertension have an impact on the population of India and China. The data in this review provide some information about the risk-factors of hypertension in terms of age and sex, unhealthy diet, overweight and obesity, alcohol, physical inactivity, tobacco. At same time, different regions have different prevalence rates. All the studies conducted in both the countries indicate the prevalence of hypertension an ascending trend with an increase in age. The results are consistent with studies conducted in other countries. However, India and China will confront different situations on the age factor. In China, population structure is facing a rapid aging because of implementation of family planning policy. Demographic dividend period is gradually disappearing. There is a huge proportion of older population in future of China. This means China will have a large number of elderly patients including hypertension patients. In India, the population structure is completely different from China. China will face more challenges than India in terms of age-specific prevalence rates of hypertension. Excess salt in-take significantly affects blood pressure. Too much sodium in your diet can cause your body to retain fluid, which increases blood pressure. Many scientific experiments have proved it. India and China are facing the same problem in this field. Both the countries have a high-salt food culture. According a research, an average per capita salt consumption in India is 13.8 gm/day. Similarly, each Chinese person consumes an average of at least 15 grams of salt every day. At the same time, different regions have different salt in-take among people in both the countries. However, the per capita salt in-take is higher than five grams in both the countries as recommended by the WHO. The Framingham Heart Study, a famous study for 44 years, estimated that excess body weight including overweight and obesity accounted for approximately 26 per cent and 28 per cent of cases of hypertension among men and women respectively. According to a WHO report 17, the prevalence rates of obesity among females and males in India are 3.7 per cent and 1.7 per cent respectively. But the rates of obesity were 10.6 per cent, 7.2 per cent, 6.4 per cent, 4.3 per cent, 6.0 per cent and 2.7 per cent respectively for large city, middle-and-small city, class 1 rural, class 2 rural, class 3 rural and class 4 rural areas in China 18. Obesity prevalence rates are in alarming proportion in India than China. There is a strong link between alcohol and non-communicable diseases such as hypertension. Hypertension and other cardio-vascular disorders such as cardiac 46

arrhythmias or heart failure are adversely effected by alcohol. According to the WHO Global Status Report on Alcohol 2004, per capita pure alcohol consumption rates amongst 15+ years were 0.82 litres and 4.45 litres in India and China, respectively 19. Hence, China should pay more attention to control alcohol-related hypertension than India. Globally, around 31 per cent of adults aged 15 years and above were insufficiently active in 2008 that included 28 per cent men and 34 per cent women. Approximately, 3.2 million deaths each year are attributed to insufficient physical activity. Sedentary activities were significantly associated with hypertension. Many studies have reported that physical inactivity has a great impact on the prevalence of hypertension. It has been observed that physical activity of Indian and Chinese population is insufficient. There is no consensus on the effect of tobacco use on hypertension. Some researches describe that tobacco use has a light impact on hypertension while others showed no affect of tobacco on hypertension. Yet, according to a WHO report, tobacco use is a risk-factor for hypertension. China and India are the largest two countries on consuming tobacco. In 2012, an estimated 28.1 per cent of adults in China (52.9% of men and 2.4% of women) were current smokers 20. Even though a large chunk of the Chinese population uses tobacco, China doesn t have a tobacco control policy. If the high smoking prevalence rate among Chinese adults persists, China will suffer from a heavy disease burden and incur serious socio-economic losses in the 21st century. The prevalence rates of hypertension were different in rural and urban areas. The population of hypertension in urban is more than in rural areas in both the countries. With the increasing of economic activities, the number of population with high blood pressure shows a rising trend in rural areas as well making the gap between rural and urban population with high BP closer. CONCLUSION Hypertension is significantly affecting India and China. The prevalence rates of hypertension are all at high level and show an ascending trend in China and India. The authors conclude that the socio-demographic and lifestyle factors are accelerating the hypertension epidemic currently in both the countries. All the risk-factors of hypertension in China and India are more or less similar. They impact the prevalence rate of high blood pressure. Accordingly, China will face more difficult situation to prevent hypertension due to a high rate of alcohol consumption. China has entered the aging society. Hence, the country will face the burden of an increasing elderly population. Because of traditional culture, Chinese people consume more alcohol than Indians. So, restricting alcohol consumption is more necessary in China. But obesity is a challenge for both India and China. The prevalence rates of obesity and overweight are increasing among the population in both the Asian giants. The affect of tobacco use is also pretty important for both the countries. With the increasing urbanization, the disparity 47

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