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Saudi Journal of Kidney Diseases and Transplantation
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Year : 2009  |  Volume : 20  |  Issue : 4  |  Page : 685-689
The prevalence, risk factors and awareness of hypertension in an urban population of Kerala (South India)

1 Department of Nephrology, Trivandrum Medical College, Kerala, India
2 Department of Medicine, Kottayam Medical College, Kerala, India

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Date of Web Publication8-Jul-2009


To determine the prevalence and possible risk factors for hypertension and prehy­pertensive state in Trivandrum City of Kerala (South India) using Joint National Committee (JNC) VII criteria, a team of trained fourth year medical students conducted a 10% random household survey in certain wards of the City. Households were selected using a random start and interval and all the members above the age of 10 years were interviewed using a standard questionnaire. The blood pressure (BP) was measured twice in each participant and the mean value of the two mea­surements was taken. A total of 482 individuals (212 males and 270 females) were interviewed in the survey. Overall prevalence of hypertension was 47% (n = 226) with equal sex ratio; 109 (21.6%) had stage-I hypertension, 45 (9.34%) had stage-II hypertension and 72 were taking drug treatment. Only 55 (11.4%) individuals had normal BP, while 201 (41.7%) were prehypertensives. Only 81 (16.8%) hypertensive patients were aware of their disease. Among the parameters such as dietary habits, physical activity, educational standards, salt intake, and diabetes mellitus, only high salt diet (P= 0.03) and diabetes mellitus (P= 0.004) had a significant association with hypertensive state. In con­clusion, the prevalence of hypertension is high but the awareness is low in our community, and intervention is necessary to impose control measures and to improve awareness.

How to cite this article:
Vimala A, Ranji SA, Jyosna MT, Chandran V, Mathews SR, Pappachan JM. The prevalence, risk factors and awareness of hypertension in an urban population of Kerala (South India). Saudi J Kidney Dis Transpl 2009;20:685-9

How to cite this URL:
Vimala A, Ranji SA, Jyosna MT, Chandran V, Mathews SR, Pappachan JM. The prevalence, risk factors and awareness of hypertension in an urban population of Kerala (South India). Saudi J Kidney Dis Transpl [serial online] 2009 [cited 2021 Jan 16];20:685-9. Available from: https://www.sjkdt.org/text.asp?2009/20/4/685/53306

   Introduction Top

Hypertension poses a significant risk for the development of heart disease and chronic kid­ney disease (CKD). As heart disease, CKD is also emerging as an important cause of mor­bidity and mortality. Worldwide, the major causes for CKD are diabetes mellitus and hyperten­sion. [1],[2],[3] In a country such as India where the per capita income is low, only 1% of the population can afford renal replacement therapy. The glo­bal response to this challenge is prevention, early detection, and treatment.

A previous study conducted among the middle­aged population of Kerala showed 54.5% pre­valence of hypertension. [4] Another study, which compared the prevalence of hypertension in urban cities, 30.7% prevalence (the highest) was noted in Trivandrum city of Kerala. [5] In Tamil­nadu, a domiciliary program that goes to the villagers in their houses, has been found to be beneficial to prevent CKD. [6]

We aim in this study to determine the preva­lence and awareness of hypertension and pos­sible factors that influence outcome of hyper­tension.

   Patients and Methods Top

The study was conducted by a household sur­vey that was carried out in certain selected wards of Trivandrum City (1.5 million popula­tion), Kerala, South India. The selection of the wards was based on the records of the Census 2001. It covered 2000 households with a popu­lation of approximately 7000 inhabitants. A 10% random sample of households was chosen for the survey by visiting every fifth house in the locality. If the inhabitants were not at home at the time of visit, the next fifth house was visi­ted. A team of four fourth year medical students of Trivandrum Medical College who were trai­ned to measure blood pressure visited the se­lected households. All the available members in the houses at the time of survey above the age of 10 years were interviewed using a detailed questionnaire, either directly or through an in­formant, the head of the family.

The detailed questionnaire contained age, sex, educational standards, occupation, dietary habits, amount of salt taken, details of associated ill­nesses, awareness of hypertension, and details of treatment of hypertension when applicable. BP was measured in the sitting position, after a resting period of 5 minutes, using a calibrated mercury sphygmomanometer. The fifth Korot­koff sound was used to determine diastolic BP. Two other BP measurements were done on each participant within 30 minutes and the mean value of the recorded BP was considered as the BP of the participant.

The survey was completed in a period of five days (morning to evening) in May 2006. A brief discussion on the importance of regular BP check up, the risk factors for the development of high blood pressure and the complications related to hypertension was done with each household by the team of medical students who conducted the survey.

   Statistical Methods Top

Univariate analysis was used to determine the statistical significance of various observations. For analysis of the data obtained, BP was gra­ded according to the JNC - VII criteria. The subjects were considered aware of their disease if they knew the need for measuring BP regu­larly, the necessity of lifestyle modifications to prevent progression to stage-I and II if prehy­pertensive, the need for treatment in stage-I and stage-II hypertension, and the possibility of de­veloping complications such as CKD and heart disease if hypertension is not adequately con­trolled. The amount of salt-intake was quan­tified and the participants were stratified into 3 categories: low salt-intake group (those who do not add salt to their food while cooking and while eating food), moderate salt-intake group (add salt to food only while cooking) and high salt-intake group (add salt to food while coo­king and while eating). For evaluation of educa­tional status, we compared two groups: schooling up to tenth standard and above tenth standard. Finally, we defined groups for physical activity that included sedentary lifestyle - only routine office work; moderate physical activity - home­makers, and or daily physical exercise, and heavy work - students, manual laborers and professionals who are active outdoor.

   Results Top

A total of 482 individuals were interviewed and screened; 212 (44%) males and 270 (56%) females. Overall prevalence of hypertension was 47% (n = 226) with almost similar sex distribu­tion (males 46% and females 48%); 109 (21.6%) had stage-I hypertension, 45 (9.34%) had stage II hypertension and 72 were taking drug treat­ment. Only 55 (11.4%) individuals had normal BP, while 201 (41.7%) were prehypertensives.

Prevalence of hypertension was 24% among subjects at age less than 30 years with male pre­ponderance. However, there was 56% and 42% prevalence of prehypertensive and hypertensive individuals, respectively, at age from 30 to 49 years with equal sex distribution, while preva­lence of hypertension was 70% among those equal to or older than 50 years with female pre­ponderance. The demographic characteristics of the study subjects are shown in [Table 1].

The prevalence of hypertension was less among educated persons (both men and women) as compared to less educated persons even, but the difference was not statistically significant. While 42% of males and 30% of females among the participants in the survey consumed vegetarian diet, the prevalence of hypertension was not statistically significantly different among sub­jects on vegetarian diet vs. mixed diet: 41% vs. 49%, respectively; P= 0.09. However, the sub­jects who consumed a high-salt diet had higher prevalence of hypertension as shown in [Table 2].

Of the 73 patients who had diabetes mellitus, 71 (97%) had hypertension and diabetics had higher risk to have coexistent hypertension as shown in [Table 3]

All the 81 previously diagnosed hypertensive study patients were confirmed to have hyper­tension and 72 of them were on drug treatment, but their blood pressures were inadequately con­trolled. Out of the 401 persons not aware of any problem, 201 (50%) were prehypertensive and were not aware of the need for periodic check­up and life style modification. Of the 154 sub­jects with newly detected hypertension 144 (93%) were not aware of the problem; however, awa­reness increased with age.

The influence of age on the prevalence of hyper­tension and the prehypertensive state was ana­lyzed statistically and is shown in the [Table 4].

   Discussion Top

Our observations are similar to the earlier stu­dy done in Trivandrum, [4] where 54.5% of the middle aged people were hypertensive accor­ding to the JNC VI criteria. The prevalence of hypertension found in our study was 47%. High prevalence of hypertension in Trivandrum City has also been reported in 1998 by Singh RB et al. [5]

This is the first community-based survey for evaluation of the prevalence of hypertension in an urban area. The overall prevalence of pre­hypertensive state in this study seems to be si­milar to the prevalence reported from North India. [7] This may suggest that if subjects in the prehypertensive groups were identified and the lifestyles modified, the onset of hypertension could be delayed or prevented as shown by several investigators. [8],[9],[10],[11],[12],[13]

In our study, 33% of the hypertensive indivi­duals were unaware of their condition. The awareness was low among the young, but in­creased with older age. The popular belief that hypertension and diabetes mellitus are diseases of the elderly may be the reason for the low le­vel of awareness among the youth. Improving awareness in the community is an important population-based strategy for prevention of com­plications of these diseases. [14]

None among the prehypertensive group was aware of predisposition to hypertension and re­quirement of life style and dietary modifications and blood pressure check-up at least annually. Vegetarian diet showed a trend towards a pro­tective effect on hypertension in our study in contrast to an earlier observation in which mixed diet showed a protective effect. [15] The aware­ness of hypertension was higher among persons with higher educational status, in contrast to the observation from a recent study from Spain. [16] Moreover, prevalence of hypertension was less among those with higher educational status.

The high prevalence of prehypertensive state among young adults detected in this study should be an eye-opener for the healthcare providers to implement educational and preventive strategies in order to reduce the burden of hypertension in the society. Increasing awareness among youngs­ters through academic institutions and audio vi­sual media may be a reasonable long-term stra­tegy for education about the disease.

Coexistence of diabetes mellitus and hyperten­sion was found to be very common in this study. The risk for the development of chronic kidney and heart disease is additive in individuals with this dangerous coexistance. [1] ,[2] ,[3] ,[17]

The prevalence of hypertension was 70% in people above the age of 70 years with a female preponderance but only 15% of them were ta­king antihypertensive medications. This finding has serious medico-social implications with the recent trends in the growth of the elderly popu­lation in Kerala are considered. The low birth rate in Kerala and the resultant small family size, the increasing number of young adults seeking employment abroad, and the under developed social welfare systems for elderly-care in the state compound the inadequate health care for the elderly individuals.

The prevalence of chronic renal failure (CRF) among adults was found to be 7850/million in a large community-based study from South Delhi. [18] The prevalence of CRF is much higher in the western societies where the prevalence is esti­mated to be 47000/million. [19] A major chunk of these patients had diabetes, hypertension, or were above 55 years. There are no large-scale population-based surveys from India seeking the prevalence of CRF among people with diabetes mellitus and hypertension. In our study, 15.2% of the hypertensive patients had diabetes me­llitus. This implies that the prevalence of CRF would be much higher in this study population and should be investigated in future studies.

The main limitation of this study is that blood pressure has been checked within a period of 30 minutes, which should have been confirmed on further follow up. However, since the study has been done in the community, which has repre­sentative samples of different regions with dif­ferent dietary habits and having different levels of physical activity, occupational and cultural characteristics, the scientific relevance of the observations is high.

We conclude that the prevalence of hyperten­sion and prehypertensive state is high in Kerala, South India. The prevalence of hypertension in­creases with older age, high dietary salt intake and co-existent diabetes mellitus. The low level of awareness of the problem among the po­pulation necessitates urgent medical and social intervention. Improvement of the awareness for hypertension and the early detection and treat­ment of high blood pressure in the community may reduce the risk of development of chronic kidney diseases and heart diseases.

   References Top

1.Gomez RA. Renal disease in Colombia. Ren Fail 2006;28:643-7.  Back to cited text no. 1    
2.Jafar TH. Hypertension and kidney disease in Asia. Curr Opin Nephrol Hypertens 2006;15:291-5.  Back to cited text no. 2  [PUBMED]  [FULLTEXT]
3.Agarwal SK. Chronic kidney disease and its pre­vention in India. Kidney Int Suppl 2005;S41-5.  Back to cited text no. 3    
4.Zachariah MG, Thankappan KR, Alex SC, Sarma PS, Vasan RS. Prevalence, correlates, awareness, treatment, and control of hypertension in a middle aged urban population in Kerala. Indian Heart J 2003;55:245-51.  Back to cited text no. 4  [PUBMED]  
5.Singh RB, Beegom R, Mehta AS, et al. Prevalence and risk factors of hypertension and age specific blood pressures in five cities: a study of Indian women. NKP Salve Institute of Medical Sciences, Nagpur, India. Five City Study Group. Int J Cardiol 1998;63:165-73.  Back to cited text no. 5    
6.Mani MK. Experience with a program for preven­tion of chronic renal failure in India. Kidney Int Suppl 2005;(94):S75-80.  Back to cited text no. 6  [PUBMED]  
7.Prabhakaran D, Shah P, Chaturvedi V, Ramakrishnan L, Manhapra A, Reddy KS. Cardiovascular risk factor prevalence among men in a large industry of northern India. Natl Med J India 2005;18:59-65.  Back to cited text no. 7  [PUBMED]  
8.Appel LJ, Brands MW, Daniels SR, Karanja N, Elmer PJ, Sacks FM; American Heart Association. Dietary approaches to prevent and treat hyperten­sion: a scientific statement from the American Heart Association. Hypertension 2006;47:296-08.  Back to cited text no. 8  [PUBMED]  [FULLTEXT]
9.Dickinson HO, Mason JM, Nicolson DJ, et al. Lifestyle interventions to reduce raised blood pre­ssure: a systematic review of randomized controlled trials. J Hypertens 2006;24:215-33.  Back to cited text no. 9  [PUBMED]  [FULLTEXT]
10.He FJ, MacGregor GA. Importance of salt in de­termining blood pressure in children: meta-analysis of controlled trials. Hypertension 2006;48:861-9.  Back to cited text no. 10  [PUBMED]  [FULLTEXT]
11.O'Shaughnessy KM. Role of diet in hypertension management. Curr Hypertens Rep 2006;8:292-7.  Back to cited text no. 11  [PUBMED]  
12.Karppanen H, Mervaala E. Sodium intake and hypertension. Prog Cardiovasc Dis 2006;49:59-75.  Back to cited text no. 12  [PUBMED]  [FULLTEXT]
13.Milan A, Mulatero P, Rabbia F, Veglio F. Salt intake and hypertension therapy. J Nephrol. 2002;15:1-6.  Back to cited text no. 13    
14.Casiglia E, Saugo M, Schiavon L, et al. Reduction of cardiovascular risk and mortality: a population based approach. Adv Ther. 2006;23:905-20.  Back to cited text no. 14    
15.Chiplonkar SA, Agte VV, Tarwadi KV, Paknikar KM, Diwate UP. Micronutrient deficiencies as predisposing factors for hypertension in lacto vegetarian Indian adults. J Am Coll Nutr 2004;23: 239-47.  Back to cited text no. 15  [PUBMED]  [FULLTEXT]
16.Perez Fernandez R, Marino AF, Cadarso Suarez C, et al. Prevalence, awareness, treatment and control of hypertension in Galicia (Spain) and association with related diseases. J Hum Hypertens 2007; [Epub ahead of print].  Back to cited text no. 16    
17.Prakash J, Hota JK, Singh S, Sharma OP. Clinical Spectrum of Chronic Renal Failure in the Elderly: a Hospital Based Study from Eas-tern India. Int Urol Nephrol. 2006 Nov 10; (Epub ahead of print).  Back to cited text no. 17    
18.Agarwal SK, Dash SC, Irshad M, Raju S, Singh R, Pandey RM. Prevalence of chronic renal failure in adults in Delhi, India. Nephrol Dial Transplant. 2005;20:1638-42.  Back to cited text no. 18    
19.Hallan SI, Dahl K, Oien CM, et al. Screening strategies for chronic kidney disease in the general population: follow-up of cross sectional health survey. Br Med J 2006;333(7577):1047.  Back to cited text no. 19    

Correspondence Address:
Joseph M Pappachan
Kottayam Medical College, Kottayam, Kerala, South India 686008
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  [Table 1], [Table 2], [Table 3], [Table 4]

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