Journal of Human Hypertension (2014), 1–6 & 2014 Macmillan Publishers Limited All rights reserved 0950-9240/14 www.nature.com/jhh
Prevalence of and risk factors for hypertension in urban and rural India: the ICMR–INDIAB study A Bhansali1, VK Dhandania2, M Deepa3, RM Anjana3, SR Joshi4, PP Joshi5, SV Madhu6, PV Rao7, R Subashini3, V Sudha3, R Unnikrishnan3, AK Das8, DK Shukla9, T Kaur9, V Mohan3 and R Pradeepa3 for the ICMR–INDIAB Collaborative Study Group The aim of the study is to determine the prevalence of hypertension (HTN) and its risk factors in urban and rural India. In Phase I of the Indian Council of Medical Research–India Diabetes (ICMR–INDIAB) study, individuals aged X20 years were surveyed using a stratiﬁed multistage sampling design, in three states (Tamil Nadu, Maharashtra and Jharkhand) and one union territory (Chandigarh) of India. Blood pressure was measured in all study subjects (n ¼ 14 059). HTN was deﬁned as systolic blood pressure X140 mm Hg, and/or DBP X90 mm Hg and/or use of antihypertensive drugs. Overall age-standardized prevalence of HTN was 26.3% (self-reported: 5.5%; newly detected: 20.8%). Urban residents of Tamil Nadu, Jharkhand, Chandigarh and Maharashtra (31.5, 28.9, 30.7 and 28.1%) had signiﬁcantly higher prevalence of HTN compared with rural residents (26.2, 21.7, 19.8 and 24.0%, respectively). Multivariate regression analysis showed that age, male gender, urban residence, generalized obesity, diabetes, physical inactivity and alcohol consumption were signiﬁcantly associated with HTN. Salt intake X6.5 g per day, showed signiﬁcantly higher risk for HTN (odds ratio: 1.4, 95% conﬁdence interval: 1.0–1.9, P ¼ 0.042) even after adjusting for confounding variables. In conclusion, prevalence of undiagnosed HTN is high in India and this calls for regular screening. Journal of Human Hypertension advance online publication, 31 July 2014; doi:10.1038/jhh.2014.57
INTRODUCTION The burden of hypertension (HTN) as a major public health problem can no longer be ignored, as evidenced by the decision of the World Health Organization (WHO) to designate high blood pressure as the theme for World Health Day 2013. HTN is a leading risk factor for non-communicable diseases globally and is responsible for 13% of global deaths.1 In adults, HTN is a major risk factor for cardiovascular disease, and frequently occurs in conjunction with diabetes.2 The risk factors for HTN include age, obesity, excess salt intake, tobacco use, lack of physical activity and excess alcohol consumption.1 India already has the second largest number of people in the world with diabetes,3 and the prevalence of HTN is also rising.4 According to WHO 2008 statistics, the prevalence of HTN was 23.1% among Indian men and 22.6% among Indian women.5 Although this is marginally lower than the global average of 29.2 and 24.8% in men and women, respectively, the absolute number of people with HTN in India remains high owing to the vast population of the country. Also the asymptomatic nature of the initial stage of the disease leads to a high number of undiagnosed cases, often ranging between 75 and 80%,6 which is the case in other low and middle-income countries as well.7 This paper reports on the prevalence of HTN in India, based on the results of Phase I of the Indian Council of Medical Research–India Diabetes (ICMR–INDIAB) study, which is a large representative national study on diabetes and other metabolic diseases in India. This 1
article presents data from Phase I of the study, covering a population of 213 million individuals.
MATERIALS AND METHODS The study subjects were recruited from the ICMR–INDIAB study, a large, ongoing cross-sectional, community-based survey involving adults of both sexes aged 20 years and above. The detailed methodology has been published earlier.8 Phase I of the study was carried out from November 2008 to April 2010. This phase included three states namely Tamil Nadu (population-67.4 million), Maharashtra (population-112.7 million), Jharkhand (population-31.5 million) and one Union Territory namely Chandigarh (population-1.4 million) located in the south, west, east and north of the country, respectively, representing all four regions of the country. The INDIAB–North East Phase involving all the eight north eastern states namely Assam, Arunachal Pradesh, Manipur, Meghalaya, Mizoram, Nagaland, Tripura and Sikkim and the ICMR–INDIAB-Rest of India Phase involving all the other states in India are currently in progress. The sample size was calculated based on the primary objective of the study, which was to estimate the prevalence of diabetes in India. Thus, the sample size was calculated separately for urban and rural areas, as previous studies show large variations in urban and rural prevalence of type 2 diabetes mellitus (approximately 10 and 4%, respectively). Using a precision of 20% and allowing for a nonresponse rate of 20%, the sample size was calculated to be 2800 individuals in rural areas and 1200 individuals in urban areas, with a total sample size of 4000 individuals per state. Thus, the sample size for the entire study once completed will be 1 24 000 individuals (28 states including two UTs and one NCT).8 This paper describes the prevalence of HTN from 16 000 individuals from the States of
Department of Endocrinology, Postgraduate Institute of Medical Education and Research, Chandigarh, India; 2Diabetes Care Center, Department of Diabetology, Ranchi, India; Department of Epidemiology and Diabetology, Madras Diabetes Research Foundation and Dr Mohan’s Diabetes Specialities Centre, Chennai, India; 4Department of Endocrinology, Lilavati Hospital, Mumbai, India; 5Department of Medicine, Indira Gandhi Government Medical College, Nagpur, India; 6Department of Medicine, University College of Medical Sciences and GTB Hospital, Delhi, India; 7Department of Endocrinology and Metabolism, Nizam’s Institute of Medical Sciences, Hyderabad, India; 8Department of Endocrinology, Jawaharlal Institute of Postgraduate Medical Education and Research, Puducherry, India and 9Department of Non Communicable Diseases, Indian Council of Medical Research, New Delhi, India. Correspondence: Dr V Mohan, Department of Epidemiology and Diabetology, Madras Diabetes Research Foundation and Dr Mohan’s Diabetes Specialities Centre, No. 6, Conran Smith Road, Gopalapuram, Chennai 600 086, India. E-mail: [email protected]
Received 13 January 2014; revised 7 May 2014; accepted 29 May 2014 3
Prevalence of hypertension in India A Bhansali et al
2 Tamil Nadu, Maharashtra and Jharkhand, and the Union Territory of Chandigarh (Phase I of the ICMR–INDIAB study). The study employed a stratiﬁed multistage sampling design.9 A three-level stratiﬁcation was done using geography, population size and socioeconomic status (SES), and the primary sampling units were villages in rural areas and census enumeration blocks in urban areas. One individual was chosen from each household following the WHO-KISH method. The study comprised a total of 16 607 individuals (5112 urban and 11 495 rural) from 363 primary sampling units (188 urban and 175 rural). Approval of the Institutional Ethics Committee was obtained before study commencement and written informed consent was obtained from all participants in the local language. In all subjects recruited, a structured questionnaire was administered to collect information regarding sociodemographic and behavioral details, physical activity and anthropometric measures including height, weight, body mass index (BMI) and waist circumference were measured using standardized techniques. Blood pressure was recorded in the sitting position in the right arm to the nearest 1 mm Hg, using the electronic OMRON HEM 7101 machine (Omron Corporation, Tokyo, Japan). The ﬁnal reading was recorded as the average of two readings taken 5 min apart. The Omron HEM 7101 blood pressure measuring device was validated as per the international validation protocol for 33 subjects. The average differences between the Omron HEM-7101 device and mercury sphygmomanometer readings were 0.3 þ / 1.9 and 0.9 þ / 1.4 mm Hg for systolic and diastolic blood pressure (DBP), respectively, which fulﬁlled the recommendation criteria of the International Protocol.10 Fasting capillary blood glucose (CBG) was determined in all subjects using One Touch Ultra glucose meter (Johnson & Johnson, Milpitas, CA, USA) after 8 h of overnight fasting. Oral glucose 82.5 g (equivalent to 75 g of anhydrous glucose) was given and a 2-h post-load CBG was collected. In individuals with self-reported diabetes, only fasting CBG was measured. In every ﬁfth subject, a semiquantitative food frequency questionnaire was administered to collect detailed information on dietary intake over the past year. Quantitation of dietary salt intake assessed the amount of salt used during cooking and/or added at the table.
Deﬁnitions Self-reported HTN. Individuals with self-reported history of HTN and on drug treatment for HTN. Newly detected HTN. Individuals with systolic blood pressure (SBP) X140 mm Hg, and/or DBP X90 mm Hg and/or on treatment with antihypertensive drugs (Joint National Committee (JNC) 7 Criteria).11 Isolated systolic HTN was deﬁned as SBP X140 and DBP o90 mm Hg (Joint National Committee (JNC) 7 Criteria).1 Isolated diastolic HTN was deﬁned as DBP X90 and SBP o140 mm Hg (Joint National Committee (JNC) 7 Criteria)).1 Generalized obesity was deﬁned as a BMI X25 kg m 2 for both genders based on the WHO Asia Paciﬁc Guidelines with or without abdominal obesity.12 Diabetes was deﬁned by the physician diagnosis of diabetes and the current use of medications for diabetes (insulin or oral hypoglycemic agents) and/or fulﬁllment of criteria laid down by the WHO Consultation Group Report, that is, a fasting CBG X126 mg dl 1 (X7 mmol l 1) and/or a 2-h post-glucose CBG value X220 mg dl 1 (X12.2 mmol l 1).13 BMI. BMI was calculated using the formula, weight (in kilograms)/height (in square meters). SES. SES for urban areas was determined by using the 2011 revised Kuppuswamy’s scale14 of SES classiﬁcation based on occupation, education and family income per month (in Rupees) as parameters. For rural areas, SES was determined using house type and the Standard of Living Index as given by National Family Health Survey (NFHS-3).9 Physical activity. Physical activity was assessed using the Global Physical Activity Questionnaire developed by the WHO.15 To assess the physical activity, domain-wise metabolic equivalent scores were calculated and individuals were categorized as sedentary, moderate and vigorous. For this article, physical activity was dichotomously coded as sedentary and active (the latter category comprising individuals who reported moderate or vigorous activity). Journal of Human Hypertension (2014) 1 – 6
Statistical analysis Statistical analyses were performed using SAS statistical package (Version 9.0; SAS Institute, Inc., Cary, NC, USA). Estimates were expressed as mean±s.d. One-way analysis of variance or Student’s ‘t’-test were used to compare groups for continuous variables and w2-test was used to compare proportions between the two groups. Multiple logistic regression analysis was used to examine the association between various exposures (age, gender, place of residence, generalized obesity, cigarette smoking, alcohol consumption, income status and literacy level) and outcome (HTN). Using backward selection, variables that remained signiﬁcant were retained in the ﬁnal model. P-value o0.05 was considered signiﬁcant. The prevalence rate and mean SBP and DBP obtained in the present study were age standardized to the 2001 Census of India using a direct method. For projections, Government of India population projections for 2011 for the respective states/UT based on 2001 Census of India were used.16
RESULTS Of the 16 607 subjects selected for Phase 1 of INDIAB, 14 277 subjects (86%) participated, of whom blood pressure measurements were available in 14 059 subjects (98.5%). Overall, the agestandardized prevalence of HTN in the four regions was 26.3% (self-reported HTN: 5.5%; newly detected HTN: 20.8%). The overall age-standardized prevalence of HTN was highest in Tamil Nadu: 27.6% (self-reported HTN: 5.6%; newly detected HTN: 22.0%) followed by Chandigarh: 25.8% (self-reported HTN: 8.0%; newly detected HTN: 17.8%), Maharashtra: 25.0% (self-reported HTN: 4.4%; newly detected HTN: 20.5%) and Jharkhand: 23.8% (selfreported HTN: 3.5%; newly detected HTN: 20.8%). The populations studied in all four regions comprised of 49.7% males, with a mean age of 40±14 years, age-standardized mean SBP of 127.3 mm Hg (95% conﬁdence interval (CI):126.9–127.6) (Male: 129.0 mm Hg (95% CI: 128.6–129.4); female: 125.9 (95% CI: 125.4–126.3)) and age-standardized mean DBP of 77.6 mm Hg (95% CI: 77.4–77.8) (Male: 78.5 mm Hg (95% CI: 78.2–78.8); female: 76.8 mm Hg (95% CI: 76.5–77.0)). Table 1 presents the sociodemographic and biochemical characteristics of subjects with and without HTN in the four regions studied. The prevalence of HTN was signiﬁcantly higher in men than in women in all regions except Jharkhand. Hypertensive subjects were older, had a greater BMI and waist circumference, and a signiﬁcantly higher prevalence of smoking, alcohol consumption, generalized obesity and diabetes than normotensive subjects in all four regions studied. Those with HTN had lower education and income levels compared with normotensive individuals. Figure 1 shows the age-standardized prevalence of HTN (selfreported, newly diagnosed and overall) in the urban and rural population of all the four regions studied. Overall, HTN was more prevalent in urban areas compared to rural areas. In urban areas, the highest prevalence of HTN (overall) was observed in Tamil Nadu (31.5% (29.5–35.3%)), followed by Chandigarh (30.7% (29.6– 35.8%)), Jharkhand (28.9% (27.6–33.6%)) and Maharashtra (28.1% (27.9–33.1%)). In the rural areas as well, Tamil Nadu had the highest prevalence of HTN (26.2% (25.2–29.7%)) followed by Maharashtra (24.0% (22.9–26.2%)), Jharkhand (21.7% (20.5– 23.9%)) and Chandigarh (19.8% (18.8–22.1%)). The prevalence of newly diagnosed HTN was higher than self-reported HTN across all three states and the UT. Overall, isolated systolic HTN was present in 10.5% of subjects in all the four regions studied (12.1% in Tamil Nadu and Jharkhand, 10.5% in Maharashtra and 7.8% in Chandigarh). Isolated diastolic HTN was present in 3.4% of subjects in all the four regions studied (4.6% in Tamil Nadu, 4.0% in Maharashtra, 3.8% in Chandigarh and 2.5% in Jharkhand). Figure 2 presents the age- and gender-speciﬁc prevalence of HTN in urban and rural areas. In all the regions, the prevalence of HTN increased with increasing age. Even in the age group of 20–24 years, the prevalence of HTN ranged from 5.4–13.9% in urban and from 9–10% in rural areas. At every age interval, the prevalence of HTN in urban areas was higher compared with rural & 2014 Macmillan Publishers Limited
Prevalence of hypertension in India A Bhansali et al
3 Table 1.
Sociodemographic and biochemical characteristics of subjects with and without hypertension
n Male, n (%) Age (years) BMI Waist (cm) Male Female SBP (mm Hg) DBP (mm Hg) Fasting CBG (mmol l 1)a 2 h PG CBG (mmol l 1)a Smoking, n (%) Alcohol, n (%)
2558 1178 (46.1) 39±13 21.8±4.0
1057 576 (54.5)* 50±15* 23.4±4.5*
2841 1381 (48.6) 38±13 20.4±3.7
1018 542 (53.2)** 49±15* 22.7±4.4*
2469 1239 (50.2) 37±13 19.8±3.4
803 405 (50.4) 48±15* 21.6±4.7*
2527 1225 (48.5) 33±10* 22.5±4.3
786 446 (56.7)* 44±14* 25.5±4.8*
78±11 73±11 120±10 75±8 5.3±1.6 6.2±1.9 502 (19.6) 523 (20.5)
84±12* 79±12* 150±18* 89±11* 5.8±2.1* 7.1±2.9* 241 (22.8)** 260 (24.6)**
76±11 68±10 119±11 74±8 5.3±1.3 6.3±1.7 274 (9.6) 300 (10.6)
84±12* 75±12* 149±16* 89±11* 5.8±2.1* 7.2±2.6* 134 (13.2)** 167 (16.4)*
75±10 70±10 119±11 73±8 5.2±1.3 6.3±1.6 301 (12.2) 671 (27.2)
83±13* 74±12* 152±17* 88±10* 5.6±2.0* 6.8±2.2* 150 (18.7)* 269 (33.5)**
80±11 76±12 119±11 73±8 5.6±1.7 6.6±2.1 402 (15.9) 376 (14.9)
90±12* 87±12* 146±16* 89±11* 6.3±2.7* 7.7±3.0* 136 (17.3) 174 (22.1)*
Education, n (%) No formal school Less than primary school Primary/high school Hr.Sec/technical UG/PG or above
733 317 1176 191 138
(28.7) (12.4) (46.0) (7.5) (5.4)
353 138 453 64 49
(33.4) (13.1) (42.9) (6.1) (4.6)$$
791 320 1207 339 180
(16.8) (16.8) (70.6) (10.9) (1.7)
355 118 405 91 48
(34.9) (11.6) (39.8) (8.9) (4.7)$
1131 184 799 246 107
(45.8) (7.5) (32.4) (10.0) (4.3)
414 42 221 76 50
(51.6) (5.2) (27.5) (9.5) (6.2)
492 98 1299 426 211
(19.5) (3.9) (51.4) (16.9) (8.3)
181(23.0) 31 (3.9) 407 (51.8) 86 (10.9) 81 (10.3)$$
Socioeconomic status, n (%) Low Medium High Generalized obesity, n(%) Diabetes, n (%)
834 884 832 519 164
(32.7) (34.7) (32.6) (20.3) (6.4)
406 307 344 356 185
(38.4) (29.0) (32.5)$$ (33.7)* (17.5)*
1072 836 931 335 145
(37.8) (29.4) (32.8) (11.8) (5.1)
425 304 289 296 146
(41.7) (29.9) (28.4) $$ (29.1)* (14.3)*
818 1140 508 207 91
(33.2) (46.2) (20.6) (8.4) (3.7)
304 349 148 170 107
(38.0) (43.6) (18.5)$$ (21.2)* (13.3)*
361 746 1418 609 167
(14.3) (29.5) (56.2) (24.1) (6.6)
150 200 436 399 163
(19.1) (25.4) (55.5) (50.8)* (20.7)*
Abbreviations: BMI, body mass index; CBG, capillary blood glucose; DBP, diastolic blood pressure; Hr Sec, higher or secondary education; n, sample size; PG, postgraduate; SBP, systolic blood pressure; UG, undergraduate. *Po0.001; **Po0.05 compared with subjects without hypertension; $P for trend o0.001; P for trend o0.05. aValues presented for individuals who underwent diabetes screening.
Age-standardized prevalence of HTN (self-reported, newly detected and overall) in urban and rural population.
& 2014 Macmillan Publishers Limited
Journal of Human Hypertension (2014) 1 – 6
Prevalence of hypertension in India A Bhansali et al
Age- and gender-specific prevalence of diabetes in four regions.
Multiple regression analysis using hypertension as dependent variable (for pooled data) Variable
Final multivariate model a Odds ratio (95% CI)
Hypertension Age (per year) Male gender Urban residence Generalized obesity Diabetes Physical inactivity Alcohol Smoking Low socioeconomic status No formal education
1.06 1.11 1.33 2.39 1.56 1.22 1.53 0.97 0.98 1.10
(1.05–1.06) (1.00–1.24) (1.18–1.49) (2.16–2.65) (1.35–1.80) (1.11–1.33) (1.34–1.73) (0.85–1.11) (0.87–1.10) (0.99–1.23)
o0.001 0.045 o0.001 o0.001 o0.001 o0.001 o0.001 0.684 0.667 0.077
(rural subjects n ¼ 1434 and urban n ¼ 525, response rate 89.5%) were evaluated for their salt intake in association with HTN risk. Overall, the mean salt intake in urban areas was signiﬁcantly higher than that in the rural areas (7.6±3.3 g per day vs 6.8±3.5 g per day, Po0.001). The mean salt intake was highest in Chandigarh (8.3±3.2 g per day), followed by Maharashtra (7.2±3.7 g per day), Tamil Nadu (6.8±3.0 g per day) and Jharkhand (5.9±3.6 g per day). The multivariate adjusted odds were computed for HTN based on total salt intake. Those who consumed more than 6.5 g per day (Xmedian) of salt had a signiﬁcantly higher risk of developing HTN as compared with those who consumed less than the median intake of salt in the population studied (OR:1.40, 95% C.I: 1.0–1.9, P ¼ 0.042) even after adjusting for potential confounders including age, gender, waist circumference, physical inactivity, household income, alcohol, diabetes, major cooking oil used and intake of carbohydrates, saturated fatty acids, polyunsaturated fatty acids, dietary ﬁber, pulses and legumes, fruits and vegetables and dairy products.
Abbreviation: CI, confidence interval. aIncluded all variables with Po0.20 in univariate analysis.
areas in all the four regions studied. In all regions studied except Jharkhand, HTN was signiﬁcantly higher in males compared to females. The estimated number of adults with HTN in the four regions are as follows: Maharashtra is estimated to have 19.0 million individuals with HTN followed by Tamil Nadu with 13.6 million, Jharkhand with 4.4 million and Chandigarh with 0.22 million. Table 2 shows the multivariate logistic regression analysis using HTN as the dependent variable. The risk factors associated in the unadjusted model were included in the multivariate model as independent variables. Age (odds ratio (OR) 1.06 (95% CI 1.05– 1.06, Po0.001)), male gender (OR 1.1 (95% CI 1.0–1.2, P ¼ 0.045)), urban residence (OR 1.3 (95% CI 1.2–1.5, Po0.001)), generalized obesity (OR 2.4 (95% CI 2.2–2.7, Po0.001)), diabetes (OR 1.6 (95% CI 1.4–1.8, Po0.001)), physical inactivity (OR 1.2 (95% CI 1.1–1.3, Po0.001)) and alcohol consumption (OR 1.5 (95% CI 1.3–1.7, Po0.001)) were signiﬁcantly associated with HTN. Details of dietary intake were available in 2189 subjects (data obtained from every ﬁfth subject), of whom 1959 subjects Journal of Human Hypertension (2014) 1 – 6
DISCUSSION HTN currently affects about one billion people worldwide11 and it is estimated that this could increase to 1.56 billion people by 2025.17 Most of the developing countries including India report a marked increase in the prevalence of HTN.18 A meta-analysis done in 200419 estimated the prevalence of HTN in India to be 25% in urban and 10% in rural areas by pooling data from various epidemiological studies and reported that the prevalence of HTN varied considerably from one region of India to another. The ﬁrst epidemiological study on HTN in India was conducted in urban north India in 1942 by Chopra and Chopra,20 following which many studies have been carried out in urban and rural areas of India.6,20–27 Several studies in India have shown an increasing trend in the prevalence of HTN among adults in both urban and rural areas. A recent systematic review of prevalence, risk factors and awareness of HTN in India28 reported that the prevalence of HTN (criteria: X140/90 mm Hg, 15 studies) in Northern India, Southern India and Western India showed a signiﬁcant increasing trend over time. The prevalence of HTN in urban and rural areas from 1991 to 2011 ranged from 13.9 to 46.3% and 4.5 to 58.8%, respectively (Northern regions: urban-27.5 to 46.3%, rural-4.5 to & 2014 Macmillan Publishers Limited
Prevalence of hypertension in India A Bhansali et al
5 35.9%; Southern regions: urban-20.0 to 44.0%, rural-11.4–45.0%; Western regions: urban 13.9–36.9%, rural-21.0%; and Eastern region: urban-24.9%, rural-33.3–58.8%). In the present study, the prevalence of HTN for urban and rural areas ranged from 28.1– 31.5 and 19.8–26.2%, respectively. Maharashtra had the greatest number of individuals with HTN, but the prevalence was highest in Tamil Nadu for both urban and rural areas. Jharkhand had the lowest prevalence of HTN, which could be due to lower intake of salt, which has been implicated as a risk factor for HTN.29 Other studies have also reported that migration from isolated low-salt societies (rural) to an urban environment with an increased salt intake is associated with increase in HTN.30,31 Thus, the higher prevalence of HTN in urban areas in our study could be attributed to increased salt intake in urban areas compared to rural areas. A cross-sectional study conducted in 26 861 individuals aged 35 to 70 years, recruited between January 2003 and December 2009 in urban and rural areas of India, as part of a multinational study conducted in 17 countries-Prospective Urban Rural Epidemiology (PURE) study, reported the prevalence of HTN to be 30.7%.32 The overall prevalence of HTN in the current study is 26.3%-thus nearly one-fourth of the adult population X20 years of age now have HTN. The higher prevalence in the PURE study could be due to the older age of the study population compared with our study. The Indian Migration Study, conducted in 2010 in rural dwelling individuals from 18 states of India (n ¼ 13 695) reported a HTN prevalence of 20% in men and 22% in women.33 In our study also we found that the prevalence of HTN in rural areas is catching up with urban prevalence rates. Various factors might have contributed to this rising trend in rural areas including consequences of urbanization such as change in life style, diet and behavioral pattern and stress. Analysis from pooling of prior epidemiological studies estimated that there were 45 million and 42 million people with HTN in urban and rural areas of India respectively in 2002.34 However, results from our study showed that the number of individuals with HTN in these three states and one UT alone was 37.2 million suggesting that HTN is becoming a major public health problem in India. In the South-East Asian region, screening studies have identiﬁed high proportions (450%) of individuals with previously undiagnosed HTN.35 The Chennai Urban Rural Epidemiology Study reported that nearly 70% of hypertensive subjects were not aware of their condition.6 Another ﬁve-city urban study in India (Kolkata, Nagpur, Mumbai, Thiruvananthapuram and Moradabad) revealed that only a quarter of hypertensive patients were aware of their diagnosis.27 In the Screening India’s Twin Epidemic study conducted in 100 centers in 10 Indian states,2 22.2% of patients, were newly diagnosed with HTN. The overall prevalence of undiagnosed HTN in this study was 20.8%, which is higher than that reported in the Chennai Urban Rural Epidemiology Study (13.4%).6 In the present study, in all three states and UT, the high ratio of newly diagnosed to self-reported HTN (ratio-3.8:1) is a cause for concern as this implies that a large segment of the population with HTN are unaware of their condition. There was also a strong relationship of obesity and diabetes with HTN prevalence in all four locations. Therefore, proper management of one condition could lead to improved outcomes and reduced burden of other co-morbidities. A systematic analysis of health examination surveys and epidemiological studies in 199 countries and territories with 786 country years and 5 4 million participants, looked at the national, regional and global trends in SBP for adults 25 years and older from 1980 to 2008 and reported that SBP is currently highest in low-income and middle-income countries.36 The systematic analysis reported that the age-standardized SBP rose in India from 1980 to 2008 in both sexes, from 120.9 mm Hg to 123.1 mm Hg in women and from 122.1 mm Hg to 123.9 mm Hg in men. Our study shows that this has further increased to 125.9 mm Hg in women and 129.0 mm Hg in men and also that & 2014 Macmillan Publishers Limited
the prevalence of Isolated systolic HTN was higher (10.5%) than that reported by other studies.6,37 Various risk factors including obesity, sedentary behavior, alcohol use, higher social class, salt intake, diabetes mellitus and smoking are associated with HTN in developing countries.38 The Chennai Urban Population Study reported that age, BMI, waist hip ratio and glucose intolerance had a signiﬁcant association with HTN.24 In another study conducted in urban North Indians, age, higher BMI and abdominal obesity, higher SES, high dietary fat and salt intake and physical inactivity were independently associated with HTN.23 In a study done in a rural area, factors like upper SES, sedentary activity, tobacco use and diabetes were signiﬁcantly associated with HTN.39 These ﬁndings were consistent with the present study ﬁndings, which revealed that age, male gender, urban residence, generalized obesity, diabetes, physical inactivity and alcohol consumption were associated with HTN. The strength of this study is that the study sample is truly representative of the regions studied in terms of geography, SES and population size, the sample size is large (n ¼ 14 059) and data on the prevalence of HTN has been obtained in both urban and rural areas, in whole states of the country. However, the study also has a few limitations. First, the cross-sectional nature of the design does not allow for cause–effect relationships to be made. Only prospective longitudinal follow-up studies can throw light on the true risk factors associated with HTN. Secondly, data from three states were used to project the number of people with HTN in India, and it is possible that these numbers might change once the entire study, comprising the other states of the country, is completed. However, the type of sampling (representing whole states and sampling of one member per household) has ensured high randomness of selection, and thereby representativeness, enhancing the credibility of our estimates. In conclusion, ﬁndings from this study show that the prevalence of HTN continues to rise across the country. As India is undergoing economic growth and demographic transition, this burden is likely to increase further. Urban areas have a higher prevalence than rural areas but this gap is being rapidly narrowed. As the majority of the population lives in rural areas,40 this ﬁnding will have important implications for planning of health services in the country. Health care systems should be strengthened for early detection and effective treatment of individuals with HTN.
What is known about topic Over the past three decades, HTN has reached epidemic proportions in India and is now a major public health problem. In addition, it is also associated with other metabolic disorders including diabetes, cardiovascular diseases, stroke and so on. Various studies have reported increasing prevalence of HTN from different parts of India particularly from urban areas. However, there has been no nationally representative study on the prevalence of HTN in India. What this study adds This national study presents the prevalence of HTN in urban and rural areas based on representative samples obtained from four regions representing North, South, East and West of India covering a population of 213 million. The sampling is made truly representative of the population in terms of geography, population size and SES. This study is of signiﬁcance because it shows large increases in prevalence of HTN not only in urban areas, but also in rural areas in India.
CONFLICT OF INTEREST The authors declare no conﬂict of interest.
Journal of Human Hypertension (2014) 1 – 6
Prevalence of hypertension in India A Bhansali et al
6 ACKNOWLEDGEMENTS We gratefully acknowledge the ICMR, New Delhi for the ﬁnancial support for the study and the ICMR–INDIAB Expert Group for their valuable suggestions and scientiﬁc inputs. We also thank the ICMR–INDIAB Quality Managers, Quality Supervisors and the ﬁeld team for smooth conduct of the study and the participants for their cooperation. This is the sixth paper from the ICMR–INDIAB Study (ICMR –INDIAB -6).
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AUTHOR CONTRIBUTIONS RMA and VM conceived the study, its design and were involved in implementation of the study, interpretation of the data and helped to draft and revise the manuscript. MD, VS, RU and RP were involved in the design and coordination of the study, interpretation of the data and drafting the manuscript. AB, VKD, SRJ and PPJ were responsible for supervision of the study in their respective states. PVR, AKD, DKS and TK were part of the study expert committee and helped revising the manuscript critically for important intellectual content. MD, VS and RP helped in the execution of the study and were responsible for maintaining quality in the study. RS and RP were responsible for data management and statistical analyses. All authors read and approved the ﬁnal manuscript.
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