Prevalence of hypertension and its risk factors among adults in central Kerala

Introduction: High blood pressure is both preventable and treatable. Community based studies on the prevalence of hypertension is now necessary to assess the prevalence of hypertension & its risk factors. Epidemiological studies to assess the prevalence of hypertension are essential to plan preventive strategies & promote the health of population. A study of the prevalence of hypertension among adults (>19 years), the association between socio-demographic and behavioral risk factors in hypertension and the treatment seeking behavior in the population in Thrissur district of Kerala was conducted. Methods: In this community based cross sectional study, 740 adults were studied for 1 year. The sampling technique used was Multi Stage Cluster sampling. Using standard questionnaire and interview, information was collected. Blood pressure was measured twice in each subject using a mercury sphygmomanometer adopting standardized techniques and their averages were taken. Results: Maximum prevalence of hypertension was in the age group 50-69 years, showing increasing trend after 40 years onwards. Of the hypertensives 43.9% were males. Among the hypertensive group, 227(79%) had an educational qualification of 12 th standard and below. Statistically significant associations of hypertension were found with educational status and BMI. Conclusion: We conclude that age group and education status were associated with hypertension.


Introduction
High blood pressure (BP) is a major public health problem in developing countries around the world and is one of the most important modifiable risk factor for cardiovascular diseases. Hypertension increases the risk of heart attacks, strokes and kidney failure. According to the World Health Statistics by WHO [1], in terms of attributable risk raised blood pressure is the foremost factor among all behavioral and physiological risk factors globally. In India cardiovascular diseases, of which hypertension is a major risk factor, are estimated to be responsible for 1.5 million deaths annually [2]. Hypertension is directly responsible for 57% of all stroke deaths and 24% of all coronary heart disease deaths in India [3]. Prevalence of hypertension in India is reported as ranging from 10% to 30.9% [4]. High blood pressure is both preventable and treatable. Community based studies on the prevalence of hypertension is now necessary to Villages were considered as clusters. The sampling was done in 2 stages. In the first stage, two taluks were selected from five taluks of Thrissur district randomly. In the second stage, 20 villages were randomly selected from two taluks. Sampling unit was a household. To obtain required sample size, 35 persons were included in each cluster. Considering 10 % drop-out rate, 37 persons were included from each cluster. In each village, the first household was selected randomly. Next to this house, 37 consecutive household were studied. One person was selected from each household using Kish table method.

Methodology
A pre-tested semi-structured and interviewer-administered questionnaire was administered. BP was recorded by the doctor with a mercury column sphygmomanometer using a standardized technique, twice with a five minute interval; in sitting position on the right arm and after rest. The average of two values was taken. The first and the fifth Korotkoff sounds were taken as indicative of the systolic and diastolic blood pressure respectively. Average of two readings of systolic and diastolic blood pressure was used as the blood pressure of the participant.

Data Collection tools
The data was collected using the following methods after informed consent. 1) Interview method using a schedule 2) Anthropometric measurement 3) Blood pressure measurement    There was a significant association among educational status and hypertension

Discussion
Total Prevalence of Hypertension: Total prevalence of hypertension in our study was 38.9%. In a study by Gupta a high prevalence of hypertension was observed among urban adults [3]. In a muticentric study in Bangladesh and India the overall prevalence of hypertension was 65% [6].
According to Anil Bindhu et al [7] the overall prevalence of hypertension in rural Thiruvananthapuram was 36%. In a population based study by Addo et al in Ghana prevalence of hypertension was higher in urban areas than in rural areas [8].
Sex and Prevalence of Hypertension: In our study 43.9% males were hypertensive and 37.2% females were hypertensive. In the study by Gupta [3] 30% of males and 33% of females in Jaipur had high prevalence of hypertension. In his study he mentioned that 31% of males and 36% of females in Thiruvananthapuram had high prevalence of hypertension. According to the multicentric study by the Hypertension Study Group [6] prevalence of hypertension did not differ significantly between sexes which were in contrast to our study.
In a study by Gupta on prevalence and determinants of hypertension in the urban population [9] isolated systolic hypertension was present in 7% of men and 2% of women, isolated diastolic hypertension was present in 65% of men and 57% of women and definite hypertension was present in 16% of men and 24% of women.
According to Anil Bindhu et al [7] prevalence of hypertension in a rural area in Thiruvananthapuram was found to be 37.9% in males and 35% in females. In a longitudinal study of risk factors of hypertension and their relation to cardiovascular disease by Wang et al [10] there was no sex difference in hypertension which is dissimilar to our study.
Age and Prevalence of Hypertension: In our study maximum prevalence of hypertension was observed in 50-69 age group. In a study by Laxmaiah [11] risk of hypertension was 6-8 times high in elderly people which compares favorably to our study. Similarly in the study by Addo et al prevalence of hypertension increased with increasing age [8]. In a community based study in Uganda by Wamala et al [12] hypertension is associated with older age. In a study by Wang [10] et al systolic hypertension was positively associated with age.
Educational Status and Prevalence of Hypertension: In our study we observed a statistically significant association between educational status and hypertension. In the study by Hypertension Study Group conducted in Bangladesh and India [6] higher educational status correlated with increase in hypertension which was similar to our study. In the community based study in Uganda by Wamala [12] hypertension is associated with having attained tertiary education.
Body Mass Index and Prevalence of Hypertension: In our study we observed a statistically significant association between body mass index and hypertension. In the multi centric study by the Hypertension Study Group [6] high body mass index correlated positively with high prevalence of hypertension. In the study by Gupta et al on prevalence and determinants of hypertension in urban population [9] high body mass index was found to be independently associated with high prevalence of hypertension.
In the study by Anil Bindhu et al [7] the risk of hypertension was 73.8% more in people with high body mass index which was similar to our study. According to the Hypertension in Diabetes Study (HDS) I [13] the hypertensive patient had a greater body mass index than the normotensive patient.
Smoking and Prevalence of Hypertension: In our study we observed that 44.16% of the smokers were hypertensive and smoking was not observed to be a risk factor for hypertension. In a study among tribal population in India by Laxmaiah et al [11] those using tobacco for smoking were at higher risk of hypertension compared to non smokers which is not similar to our study. In another study on prevalence of hypertension [9] smoking was independently associated with high prevalence of hypertension. In the Strong Heart Study by Wang et al [10] systolic blood pressure was negatively associated with smoking.
Physical Exercise and Prevalence of Hypertension: In our study we observed no association between physical exercise and prevalence of hypertension. According to the study by Gupta [3] there is a strong correlation between changing lifestyle factors and increase in hypertension. In the study by Hypertension Study Group [6] physical activity was inversely related to the prevalence of hypertension. In a study on physical activity in prevention and treatment of hypertension in obese by Fagard [14], the weighted net reduction of blood pressure in response to dynamic physical training averaged 3.4/2.4 mmHg which Public Health Review: International Journal of Public health Research Available online at:www.publichealthreview.in 25|P a g e appeared to be unrelated to initial body mass index and to its training induced changes. It was found by Fagard [14] that exercise was less effective than diet in lowering blood pressure and adding exercise to diet did not appear to further reduce blood pressure.
In a study in Australia by Halbert et al [15] aerobic exercise training reduced systolic blood pressure by 4.7 mmHg and diastolic blood pressure by 3.1 mmHg compared to non exercising control group. The blood pressure reduction seen with aerobic exercise training was independent of the intensity of exercise sessions per week.
Dietary Salt Intake and Prevalence of Hypertension: In our study we observed no correlation between added salt intake and prevalence of hypertension. The study in Ghana by Addo et al [8] found that high blood pressure was associated with increased salt consumption.
A study on dietary approaches to treat and prevent hypertension by Lawrence et al [16] found that in hypertensive patients already on drug therapy a reduced salt intake could further lower blood pressure.
In a study by SK Ha [17] on dietary salt intake and hypertension, moderate reduction of salt intake was an effective measure to reduce blood pressure. Reduction in dietary salt from 9-12g/day to the recommended level of less than 5-6 g/day will have major beneficial effects on cardiovascular health [17].

Conclusion
We conclude that age group and education status were associated with hypertension. We recommend further detailed studies in this area.