|Year : 2015 | Volume
| Issue : 2 | Page : 153-157
Prevalence and covariates of adult hypertension: A community-based cross-sectional study in the rural areas of Nagpur
Sanjay Kumar1, Deepanjan Ray1, Pushpa Moreshwar Durge2, Samim Ferdows3, Gautam Ghose1
1 Department of Community Medicine, IQ City Medical College, Durgapur ,West Bengal, Kolkata, India
2 NK Salve Institute of Medical Sciences and Research Center, Nagpur, Maharashtra, India
3 Department of Community Medicine and Biostatistics, IQ City Medical College, Durgapur ,West Bengal, Kolkata, India
|Date of Web Publication||13-Mar-2015|
C 87, New Garia Housing Development Cooperative Society, Kolkata - 700 094
Source of Support: None, Conflict of Interest: None
Introduction: Hypertension is an iceberg disease. A few hypertensive patients are actually aware of their status and only half of them are actually treated. It is a silent killer disease and hypertensive people die prematurely. A wide disparity exists between the prevalence of hypertension in developed and developing regions. Materials and Methods: A cross-sectional community-based study involving 574 adult people from the rural community in Nagpur was selected through systematic random sampling from December 2008 to April 2009. Blood pressure was measured with a sphygmomanometer properly standardized and anthropometry was performed. Data were analyzed with SPSS statistical software (version 19.0). Results: The prevalence of hypertension was 20.38%, and the prevalence was higher among males. Age and weight were significant covariates for hypertension. Conclusion: In the present study, it is revealed that as the age advances, the prevalence of hypertension also increases. This was statistically significant. Hypertension was more prevalent in males than in females.
Keywords: Covariates, hypertension, prevalence, rural
|How to cite this article:|
Kumar S, Ray D, Durge PM, Ferdows S, Ghose G. Prevalence and covariates of adult hypertension: A community-based cross-sectional study in the rural areas of Nagpur. Med J DY Patil Univ 2015;8:153-7
| Introduction|| |
Hypertension is an iceberg. It became evident in the early 1970s itself that only half of the hypertensive subjects in the general population of the most developed countries were aware of the condition, and only about half of those aware of the problem were being treated. If this is the situation with highly developed countries, the proportion of patients treated in developing countries would naturally be far too less. 
Hypertension is an important worldwide public health challenge because of its frequency and concomitant risks of cardiovascular and kidney diseases. It is the most common cardiovascular disorder affecting at least 20% of the adult population in several countries.  It is also one of the most important risk factors for cardiovascular mortality, accounting for 20-30% of all deaths.  It has been identified as the leading risk factor for mortality and is ranked third as a cause of disability-adjusted life years.
The prevalence of hypertension in various regions of the world has been widely reported; however, no information has been compiled for its prevalence and absolute burden around the world. An accurate estimate of the worldwide prevalence of the condition is essential as a source of primary information and for rational planning of health services.
Coronary heart disease (CHD) is estimated to be the most common cause of death globally by 2020. Hypertension is one of the most important modifiable risk factors for CHD in the western and Asian populations. The prevalence of hypertension in developing countries is different from that in the developed countries. Because India is a very largely populated and typically developing country, community surveys have documented that, between three and six decades, the prevalence of hypertension has increased by about 30 times among urban developers and by about 10 times among the rural inhabitants. 
Hypertension is a risk factor for all the clinical manifestation of atherosclerosis. It is an independent predisposing factor for heart failure, coronary artery disease stroke, renal disease and peripheral arterial disease (PAD). The Multiple Risk Factor Intervention Trial (MRFIT) demonstrated a continuous and graded influence of both systolic blood pressure (SBP) and diastolic blood pressure (DBP) on coronary heart disease mortality extending down to SBP of 120 mmHg.  Hypertension is generally perceived to be a result of many contributing factors such as genetic predisposition, dietary factors such as excess salt intake and cholesterol and psychological factors such as anxiety and stress of the modern day lifestyle.
Hypertension is a silent killer and hypertensive patients die prematurely. This is because of the effect of hypertension on the three target and vital organs like the heart, brain and kidneys. The chronically elevated BP by itself can affect these organs directly or damage the arterial tree, which in turn affects various other organs systems.  The present study was carried out with the objective to determine the prevalence of hypertension and to assess the various risk factors associated with hypertension among adults (18 years and above) in the rural area of Nagpur, Maharashtra.
| Materials and Methods|| |
A community-based study with a cross-sectional design was conducted in a rural field practice area of the NKP Salve Institute of Medical Sciences and Research Centre & Lata Mangeshkar Hospital, Nagpur, which is a tertiary care hospital, from December 2008 to April 2009. The total population of this village is 7532 and the adult population (18 years and above) is 4516 (Census 2001). Initially, a pilot study was carried out upon 100 adult subjects to estimate the prevalence of hypertension, which came was found to be 23%. Using this prevalence (23%), the sample size was calculated as 574 by using the formula N = Zα2 pq/L, 2 where, Zα = 1.96 (standard normal deviate at the desired 95% confidence level), P = 23, q = 100-p, L = allowable error. Subjects who participated in the pilot study were excluded from the final study. All the adult population of both sexes from that village comprised our study population. At first, a sampling frame was constructed with the 4516 adult population with the help of a recent census report. Then, the sample interval was determined to be 7 by 4516/574. Firstly, one random number was chosen, which is equal or less than 7, and it was found to be 4. Therefore, the fourth person was selected and then every seventh person was selected subsequently, i.e. the 11 th , 18 th , 25 th person, and so on.
The study's subjects' socioeconomic status was classified by the modified B. G. Prasad Scale (2004) (I. Upper high ≥ 10,000; II. High = 5000-9999; III. Upper middle = 3000-4999; IV. Lower middle = 1500-2999; V. poor = 500-1499; VI. Very poor = <500).  BP was measured in a seated posture, with feet on the floor and arm supported at the level of the heart by using the auscultatory method with a standardized calibrated mercury column sphygmomanometer with an appropriate-sized cuff encircling at least 80% of the arm. Measurement was taken only when the persons were seated quietly for at least 5 min in a chair and who avoided caffeine, exercise and smoking at least 30 min prior to measurement. Altogether, two measurements were made and the average was recorded. SBP is the first of two or more sounds that is heard (phase 1), and DBP is the point before the disappearance of sounds (phase 5). The operational definition of hypertension was taken from The Seventh Report of the Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure (JNC 7).  Anthropometric measurements taken were weight and height as per the standard technique.  The study subjects found to be hypertensive and who needed referral were referred to a tertiary care hospital for consultation, further investigation and further management.
The collected data were compiled on Microsoft Excel worksheets (Microsoft, Redwoods, WA, USA). Significance of association between the two attributes was analyzed using the χ2 test followed by multiple linear regression with different variables using SPSS 19.0 software. A P-value less than 0.05 was considered as being statistically significant.
Of 574 subjects, 246 (42.8%) were males and the remaining 328 (57.2%) were females. Majority of the study subjects belonged to the age group of 28-37 years, i.e. 27.5%, followed by 24.9% in the age group of 18-27 years. Most of the study subjects belonged to social class IV (28.24%), followed by social class III (21.08%) of the Modified B. G. Prasad Scale (2004).  According to physical activity, 49% of the subjects were moderate workers, while 20.9%, 20.7% and 9.4% were sedentary, light and heavy workers, respectively.
The overall prevalence of hypertension was found to be 20.38%. About 20.73% had normal BP and 58.90% belonged to the pre-hypertensive group. Stage I and stage II hypertensives were 17.59% and 2.78%, respectively. A higher prevalence of hypertension was noted among males (52.1%) compared with females (47.9%). About 95% of the hypertensives were sedentary workers, while the remaining 5% were light workers.
The prevalence of pre-obesity and obesity were 13.3% and 3.8%, respectively. 82.9% of the study subjects belonged to the normal body mass index (BMI) category.
Among respondents, 168 (29.3%) were tobacco and gutkha users, followed by 73 (12.7%) smokers and 62 (10.8%) alcoholics. The proportion of male hypertensives (52.1%) were more compared with female hypertensives (47.9%).
As the age group increased, the proportion of hypertensive patients in the different age groups also increased, with the exception of 48-57 years, and this association was found to be statistically significant by a linear trend of the chi square test [Table 1].
|Table 1: Distribution of the hypertensive and normotensive subjects according to age group, n = 574|
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The prevalence of hypertension was higher in males (24.60%) than in females (17.18%), and it was statistically significant [Table 2].
|Table 2: Distribution of the hypertensive and normotensive subjects in both sexes n = 574|
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The correlation matrix revealed a significant correlation of SBP with weight and age, whereas DBP had a significant relation with weight, height and age [Table 3].
|Table 3: Correlation matrix for systolic and diastolic blood pressure with other variables|
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For SBP, multiple linear regression models were formulated with age and weight as independent variables in a stepwise manner. The equations were as follows [Table 4].
|Table 4: Regression co-efficient and their significance in multiple linear regressions for systolic blood pressure among the study subjects|
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Y SBP = 112.591 + 0.241 Age
Y SBP = 101.686 + 0.212 Age + 0.204 Weight
Weight and age had a significant association with SBP, and age alone contributed to 5.8% variations of SBP, while weight explained 4.1% variations of SBP.
Multiple linear regression models were formulated with DBP as a dependent variable and age, weight and height as independent variables in a stepwise manner. The equations were as follows [Table 5]:
Y DBP = 71.089 + 0.238 Weight
Y DBP = 69.087+ 0.089 Age + 0.226 Weight
|Table 5: Regression co-efficient and their significance in multiple linear regressions for diastolic blood pressure among the study subjects|
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Weight and age had a significant association with DBP and weight alone explained 5.7% variations in DBP, while age alone explained 0.8% variations of DBP.
| Discussion|| |
Hypertension is a silent killer, and its prevalence varies from region to region. Hypertension has a multifactorial etiology, with some conditions being modifiable and some not. Hypertension is responsible for premature death through involvement of target organs.
This present study was conducted to determine the prevalence of hypertension, and it was found to be 20.38%, while 58.90% of the subjects belonged to the pre-hypertensive category and 20.73% of the subjects had normal BP. Of the 20.38% hypertensives, 17.59% and 2.78% belonged to stage I and II hypertension, respectively. A similar finding was also noted by Janas et al. in central India, where the prevalence was 22.01%.  Deshmukh et al. mentioned the prevalence of hypertension in rural Wardha to be 21.08%,  Haldiya et al. observed the prevalence of hypertension in the Gochipura village of the desert part of Rajasthan to be 20.01%,  Shanthirani et al. found the prevalence of hypertension in a selected rural south Indian population to be 21.01% and  Midha et al. observed the prevalence of hypertension to be 23.3% and that of isolated systolic hypertension to be 4.3% in Lucknow. 
In contrast, Reddy et al. observed a much lower prevalence of hypertension of 8.06% in Tirupati. 
Age was found to be significantly associated with hypertension, as the proportion of hypertensives increased with an increase in age group. In a multivariate model also, age became an important predictor of both SBP and DBP. But, age alone was not the sole contributory factor, as other independent variables were also involved in the web of causation of BP, like environmental factors, life style, urbanization, modernization, obesity, sedentary habits, etc. Similar to the present study, Prashanth et al. found that as the age increased, the prevalence of hypertension also increased. With the advance in age from 28 to 49 years, the prevalence was higher in males and, afterwards, the females took over.  Haldiya et al. (2004) also reported that the prevalence of hypertension was increasing with increase in the age. 
It has been observed that the overall prevalence of hypertension is less in females, i.e. 17.1%. When further analyzed, it may been observed in a later age group that the prevalence is higher in females than that in males, which may be due to the lack of estrogen and increased obesity, and this difference between sex and hypertension has been found to be statistically significant.
Prashanth et al. mentioned that as the age increases, the prevalence of hypertension also increases. With the advance in age from 28 to 49 years, the prevalence is higher in males and, afterwards, the females take over. These findings are similar to the present study.  Jajoo et al., and  Lt Col Agarwal et al.  also observed similar results in their studies.
In a multiple linear regression model (stepwise method), age and weight were found to be significantly associated with high SBP and DBP. In our study, two significant variables - age and weight - together explain 9.9% variations of SBP and 6.8% variations of DBP. BP is dependent on many factors. We have only included some of them. Hence, the remaining unexplained variation of BP is either not included in the model or not yet known by the existing literature. Midha et al. also observed a significant increase in the prevalence of isolated systolic hypertension with higher age and BMI both in bivariate and in multivariate logistic regression.  Gothankar observed a significant association between obesity (assessed by BMI) with hypertension and diabetes. 
| Conclusions|| |
The classification of hypertension was performed using the seventh report of the Joint National Committee on Prevention, Detection, Evaluation and Treatment of High Blood Pressure (JNC 7 criteria). Of the 574 study subjects, 20.73% of the participant had normal BP. It has been observed that a large number of participants, 58.90%, could be categorized in the pre-hypertensive group. 20.38% of the participants were hypertensive (stage I-17.59% and stage II-2.78%).
In the present study, it is revealed that as the age advances, the prevalence of hypertension also increases. This was statistically significant. Hypertension was more prevalent in males than in females.
- The increasing trend of prevalence of hypertension with increasing age strongly suggests to prepare and implement a community-based "High Risk" screening program to prevent the modern epidemic of hypertension.
- The large number of the pre-hypertensive individuals according to the JNC 7 criteria may show early progression of hypertension and possibly coronary artery disease, which is common in India, and should be kept under surveillance and extensive Behavioral Change Communication activities should be a part of an integral prevention program.
- There is a shift of hypertension toward the young population; hence, primordial prevention and tracking of hypertension activities should start from the school level and early adolescence periods.
Non-inclusion of other possible variables like waist circumference, hip circumference, waist hip ratio, addiction, dietary habit and exercise history might be the limitations of this study.
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[Table 1], [Table 2], [Table 3], [Table 4], [Table 5]