Title: Prevalence and incidence of hypertension: Results from
a representative cohort of over 16,000 adults in three cities of
Authors: Dorairaj Prabhakaran, Panniyammakal Jeemon,
Shreeparna Ghosh, Roopa Shivashankar, Vamadevan S. Ajay,
Dimple Kondal, Ruby Gupta, Mohammed K. Ali, Deepa
Mohan, Viswanathan Mohan, Masood M. Kadir, Nikhil
Tandon, Kolli Srinath Reddy, K.M. Venkat Narayan
Reference: IHJ 1211
To appear in:
Received date: 26-3-2017
Accepted date: 27-5-2017
Please cite this article as: Dorairaj Prabhakaran, Panniyammakal Jeemon, Shreeparna
Ghosh, Roopa Shivashankar, Vamadevan S.Ajay, Dimple Kondal, Ruby Gupta,
Mohammed K.Ali, Deepa Mohan, Viswanathan Mohan, Masood M.Kadir, Nikhil
Tandon, Kolli Srinath Reddy, K.M.Venkat Narayan, Prevalence and incidence of
hypertension: Results from a representative cohort of over 16,000 adults in three cities
of South Asia (2010), http://dx.doi.org/10.1016/j.ihj.2017.05.021
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Prevalence and incidence of hypertension: Results from a representative cohort of over
16,000 adults in three cities of South Asia.
Short title: Incidence of hypertension in South Asia.
Authors: Dorairaj Prabhakaran1,2, Panniyammakal Jeemon1,2, Shreeparna Ghosh1,2, Roopa
Shivashankar1,2, Vamadevan S Ajay1,2, Dimple Kondal1,2, Ruby Gupta1,2, Mohammed K Ali2,3,
Deepa Mohan4, Viswanathan Mohan4, Masood M Kadir5, Nikhil Tandon2,6, Kolli Srinath
Reddy1,2, K M Venkat Narayan2,3.
1Public Health Foundation of India, New Delhi, India
2Centre for Control of Chronic Conditions, New Delhi, India
3Rollins School of Public Health, Emory University, Atlanta, USA
4Madras Diabetes Research Foundation, Chennai, India
5Aga Khan University, Karachi, Pakistan
6All India Institute of Medical Sciences, New Delhi, India
The authors’ takes responsibility for all aspects of the reliability and freedom from bias of
the data presented and their discussed interpretation.
Prof. D Prabhakaran
Vice President, Public Health Foundation of India
Director, Centre for Control of Chronic Conditions
Sector 44, Plot 47, Gurgaon, NCR, Haryana, 122001
Background: Despite high projected burden, hypertension incidence data are lacking in
South Asian population. We measured hypertension prevalence and incidence in the Center
for cArdio-metabolic Risk Reduction in South Asia (CARRS) adult cohort. Methods: The CARRS
Study recruited representative samples of Chennai, Delhi, and Karachi in 2010/11, and
socio-demographic and risk factor data were obtained using a standard common protocol.
Blood pressure (BP) was measured in the sitting position using electronic
sphygmomanometer both at baseline and two year follow-up. Hypertension and control
were defined by JNC 7 criteria. Results: In total, 16,287 participants were recruited
(response rate=94.3%) and two year follow-up was completed in 12,504 (follow-up
rate=79.2%). Hypertension was present in 30.1% men (95% CI: 28.7-31.5) and 26.8% women
(25.7-27.9) at baseline. BP was controlled in 1 in 7 subjects with hypertension. At two years,
among non-hypertensive adults, average systolic BP increased 2.6 mm Hg (95% CI: 2.1-3.1),
diastolic BP 0.7 mm Hg (95% CI: 0.4-1.0), and 1 in 6 developed hypertension (82.6 per 1000
person years, 95% CI: 80.8-84.4). Risk for developing hypertension was associated with age,
low socio-economic status, current alcohol use, overweight, pre-hypertension, and
dysglycemia. Risk of incident hypertension was highest (RR=2.95, 95% CI: 2.53-3.45) in
individuals with pre-hypertension compared to normal BP. Collectively, 4 modifiable risk
factors (pre-hypertension, overweight, dysglycemia, and alcohol use) accounted for 78% of
the population attributable risk of incident hypertension. Conclusion: High prevalence and
poor control of hypertension, along with high incidence, in South Asian adult population call
for urgent preventive measures.
Key words: Hypertension, prevalence, incidence, South Asia, India
Hypertension is a common risk factor for cardiovascular disease (CVD) and a major global
public health problem . Globally, hypertension affects approximately one in four adults
 and results in over ten million deaths annually . Furthermore, low- and middle-income
countries (LMIC) contribute to nearly two-thirds of the mortality attributable to
hypertension . Although the average systolic blood pressure (SBP) is decreasing
worldwide since 1980’s at the rate of 1 mmHg SBP per decade, it is increasing in LMICs,
especially in the South Asian population . There are several studies that document the
prevalence of hypertension in South Asian countries [6-8], and numerous meta-analyses
have unequivocally demonstrated that treating and effectively lowering blood pressure (BP)
is associated with reductions in cardiovascular events and mortality [9, 10]. However, the
treatment and control among prevalent hypertension cases are relatively poor in resource
poor settings, though data are quite limited and little is known about hypertension
management in South Asia .
Studies conducted in the Indian sub-continent suggest that hypertension onset occurs
relatively early in life  and is often associated with clustering of multiple cardiovascular
diseases risk factors . However, there is paucity of data on the incidence and factors
associated with progression to hypertension in this population. Reliable data on
hypertension incidence is important to estimate the future burden of hypertension and to
identify potential risk factors and subpopulations to target with preventive interventions.
In this report, we used data from a large, urban population cohort representative of three
large cities in South Asia with the objective to examine prevalence, treatment and control,
two year incidence, and factors associated with incident hypertension.
The CARRS Study  recruited representative population cohorts of three metropolitan
urban cities in south Asia with large, growing, and heterogeneous populations, namely
Chennai, Delhi and Karachi. The cities were choosen based on convenience. The detailed
methods including sample selection and measurements have been published elsewhere
. Briefly, households were selected in each of the three cities using a multi-stage cluster
random sampling technique (selection of districts followed by random selection of
municipal wards or census enumeration blocks and finally the selection of households
within these sampling units) to ensure representativeness of the population. Two
participants, one man and one woman, aged 20 years or older, were selected from each
household based on “Kish method” as used in the WHO’s STEPS surveys .
Trained field workers collected socio-demographic and risk factor data from all eligible
participants using a structured questionnaire. Baseline assessment was done in year 2010-
11. They also measured height, weight, waist circumference, systolic and diastolic BP from
all participants using standardized equipment and measurement techniques. Blood pressure
was recorded in the sitting position using electronic sphygmomanometer; Omron HEM-7080
and HEM-7080IT-E; Omron Corporation, Tokyo, Japan (certified by the British Hypertensive
Society and the American association for Advancement of Medical Instrumentation [AAMI]
protocols). A minimum of 2 measurements were taken, and 5 minutes apart. A third reading
was also taken if the difference between first and second readings were ≥ 10 or ≥ 5 mm Hg
for systolic and diastolic BP, respectively. The mean of the last two was used for analyses.
Additionally, fasting blood samples were also collected for biochemistry analyses. Standard
assay methods for assessment of diabetes (plasma glucose, haemoglobin A1c) and
dyslipidemia (total cholesterol, VLDL-cholesterol, LDL- cholesterol, HDL-cholesterol and
triglycerides) were used across the three sites. All laboratories participated in an external
quality assurance program (RIQAS) from RANDOX for clinical chemistry, lipids and HbA1c.
Performance of all participating labs were within the acceptable levels of <2 in the Cycle
Average Standard Deviation Index (score close to zero indicates optimal performance) for all
the parameters in the RIQAS. A summary of all surveillance indicators, measures, methods
and instruments used in the study has been published in detail .
Trained field workers contacted all the study participants in the baseline survey annually
and collected information on risk factors using a structured questionnaire. Additionally,
anthropometry measurements and blood pressure readings were taken from all eligible
participants during the second year follow-up. We used the same make of equipment for BP
and anthropometric measurements, and standardization procedures for all study related
measurements in the annual surveys as in the baseline survey. Year-2 follow-up was
conducted in 2013-14.
Hypertension prevalence, awareness, and treatment
Hypertension was defined as SBP of ≥140 mmHg and/or a diastolic blood pressure (DBP) of
≥90 mmHg and/or self-reported treatment for hypertension. Similarly, incident
hypertension was defined as follow-up SBP of ≥140 mmHg and/or DBP of ≥90 mmHg and/or
self-reported diagnosis of hypertension by a qualified physician among those who were not
hypertensive at baseline . Pre-hypertension was defined as SBP of ≥120 and/or DBP of
≥80 among individuals without hypertension. Incidence was estimated in individuals without
hypertension at baseline.
To estimate awareness, treatment, and control of hypertension, we used the common
denominator of total number of individuals with hypertension. Participants who had been
told that they had hypertension by a healthcare professional and self-reported their status
were categorised as ‘aware’, and those who reported current use of prescribed anti-
hypertensive medication/s were categorised as ‘treated’. ‘Control of hypertension’ was
defined as having an average of <140 and <90 mmHg for SBP and DBP, respectively, in
hypertensive subjects at baseline. Parental history of hypertension was defined as self-
reported status of treatment of hypertension in parents when they were <60 years old.
Socioeconomic Status (SES)
Household asset index and education were used to describe the SES of each participant.
Principal components analysis was used to estimate cumulative household assets based on
weighted scores for ownership of different household assets. Asset scores were then
divided into tertiles of SES . Education categories included in the analyses were ES1;
“graduation & above”, ES2; “up to secondary”, ES3; “up to primary”, and ES4; “illiterates or
individuals with no formal education”.
Physical activity was assessed using International Physical Activity Questionnaire (IPAQ).
Waist circumference was used to define central obesity (men: ≥90 cm and women: ≥80 cm).
A body mass index (BMI) of ≥25 kg/m2 was defined as overweight. Diabetes was defined as
having either HbA1c value more than equal to 6.5% or fasting blood glucose more than
equal to 126 mg/dL or self-reported glycemia-lowering medications. Prediabetes was
defined as having HbA1c value between 5.7 to 6.5% and/or fasting glucose between 100 to
125 mg/dL. Dysglycemia was defined as either pre-diabetes or diabetes. Chronic kidney
disease (CKD) status was derived from serum creatinine based estimated glomerular
filtration rate (eGFR) measurements using the Chronic Kidney Disease Epidemiology
Collaboration (CKD-EPI)  study equation. An eGFR of less than 60 ml/min/1.73 m2 was
defined as CKD. We did not have data from Karachi on serum creatinine.
Research ethics oversight
The Institutional Review Boards (IRBs) of the Public Health Foundation of India, New Delhi,
All India Institute of Medical Sciences, New Delhi, Madras Diabetes Research Foundation,
Chennai, India, Aga Khan University, Karachi, Pakistan, and Emory University, Atlanta, USA
approved the CARRS study. All respondents gave written informed consent, themselves or
through a next of kin/family member in the case of illiterate respondents, prior to
enrolment and participation in the study.
The characteristics of the study population were summarized separately for men and
women. The data were presented as mean with their standard deviation (SD) for continuous
variables or as percentages for categorical variables. All estimates of mean BP, prevalence
and incidence of hypertension were age-standardized to the 2010 World Bank regional
population. Estimates were also adjusted based on survey weights to account for population
representation due to sampling at different levels in each cluster. Prevalence estimates
were calculated after accounting for the complex multi-stage survey design, stratification,
and sampling weights.
Incidence of hypertension was estimated using follow-up data collected up to the second
year among non-hypertensive individuals at baseline. Uneven response rate in the follow-up
surveys in different risk groups was adjusted by inclusion of weights generated for non-
response. Initially, logistic regression model coefficients were generated to estimate the
probability of non-response after adjusting for baseline variables such as location (city), age,
sex, education, tobacco use, BMI, pre-hypertension and diabetes. Further, we used an
inverse propensity score as a weight in estimating the incidence of hypertension. Incidence
rates were calculated per 1000 person years of follow-up and also as cumulative
percentages over two year follow-up period with their 95% confidence intervals.
Generalised linear model with Poisson family was employed to calculate the incidence
relative risk ratio (RR) of potential risk factors of hypertension. Multivariable models
included all baseline variables that were associated with incident hypertension in the
bivariate models at 2nd year follow-up (p<0.05). Parental history of blood pressure before
age 60 was also included in the multivariable model. Analyses were repeated after imputing
missing co-variates at baseline by using multiple imputation involving chained equations.
The methods of multiple imputation have been explained elsewhere . Proportion of
data missing ranged from 1% for socio-demographic data to 23% for body weight. Multiple
imputation was done using multiple imputation chained equations (MICE) approach for all
missing observations in the exposure variables of interest at baseline. Ten imputed datasets
were generated. Imputed values of missing continuous variables were modelled using linear
regression and predictive mean matching, and imputed values of ordinal variables were
modelled using ordinal logistic regression. Model convergence was checked, and diagnostics
were performed on the imputed dataset. Population attributable fraction (PAF) of major
modifiable risk factors were also estimated directly from the RR coefficients (Box 1, online
Enrolment and Response rate
We approached a total of 17,274 individuals in 10,002 households in the three study sites
and 16,287 participants were recruited (the overall response rate was 94.3% at the
participant level; 6,906 Chennai [90.9%], 5,364 Delhi [98.9%], and 4,017 Karachi [94.3%]).
There were 2393 households with single subjects (827 males and 1566 females). Fasting
blood samples were collected at baseline from 13,720 of the participants (response
rate=84.2%). The response rate in the first, second and either of the initial two annual
follow-up surveys were 78.6%, 79.2% and 93.2%, respectively. Individuals with elevated
levels of CVD risk factors (for example; elevated BP in the prehypertension range)
responded more than individuals with all optimal level risk factors. In the second annual
follow-up survey the odds of participation among tobacco users [OR: 1.19; 1.04-1.36], and
individuals with pre-hypertension [OR: 1.18; 1.02-1.36] were high as compared to non-users
and normotensives, respectively.
General characteristics of the study population
The mean age (SD) of the population was 42 years (13.3) and 40 years (12.9) in men and
women, respectively. Women were 52% of the study population. Nearly 55% of men and
41% women reported more than secondary education, and one of five individuals was
either illiterate or had no formal education (Table 1). Men were relatively older in Karachi
(mean age 43.2, SD=16.2 years) as compared to Chennai (41.0, 13.1) and Delhi (42.2, 11.8).
Less than primary school education among participants was more frequent in Karachi than
Chennai or Delhi (Table 1).
Mean blood pressure levels
The mean SBP was highest in Delhi (men; 129±17 mmHg and women; 121±18) and lowest in
Karachi (men; 123±20 mmHg and women 117±23). In older age groups, mean SBP was
higher in both men (mean SBP in <=24 and >=65 years age group: 117.4 and 140.1 mmHg)
and women (105.1 and 139.3 mmHg) (Table S1). DBP was also elevated in higher age groups
until the age of 64 years and then started showing a decline especially in Delhi.
Prevalence, awareness, treatment and control of hypertension
Consistent with the mean blood pressure levels, the age adjusted prevalence of
hypertension in men was highest in Delhi (37%) and lowest in Karachi (24%). Twenty eight
percent of women in Delhi and Karachi were hypertensive, and in Chennai, 29% men and
25% women were so (Figure S1). The prevalence was higher with age in both men and
women (Table S2). Hypertension prevalence was particularly high in men <24 years in Delhi
in comparison to adults of same age category in other cities (Table S2). Prehypertension was
prevalent in nearly one third (30.3%) of the study population (men: 36%, and women:
25.2%) and the overall prevalence was highest in Delhi (33.3%) and lowest in Karachi
(26.5%) (Figure S1).
Among those with hypertension at baseline, awareness levels were highest in Karachi (men;
27% and women; 57%). They were 24 and 38% respectively, in Chennai and 22 and 36%
respectively, in Delhi. Overall, treatment and control levels of hypertension, respectively,
were very low in Delhi (men; 18 and 7%, women; 33 and 16%) and Chennai (men; 22 and
10%, women; 37 and 20%). More than half of women (55%) in Karachi were treated for
hypertension, while BP control status was observed in 27% (Figure 1 and Table S3).
Although hypertension control rates were higher in individuals with established disease
conditions such as diabetes (22.9%), chronic kidney disease (22.4%), heart disease (38.2%),
and stroke (32.2%), they were still far less than optimal level (Table S4). Based on self-
reported data at the time of the survey, more than two third (68.3%) of individuals with
known hypertension were taking drugs regularly.
Hypertension awareness, treatment, and control showed a positive linear relationship with
educational status (the rates were lowest in illiterate or participants with no formal
education and highest in participants with more than graduate level education) only in men
(Figure S2). However, hypertension prevalence was not associated with educational status.
Incidence of hypertension
The mean SBP and DBP each increased in both men and women without hypertension at
baseline during the two year follow-up period (Figure S3). The highest secular increase in
SBP was in women in the older age groups (>55 years) (Table S5). On average SBP increased
by 2.6 mm Hg (95% CI: 2.1-3.1) and DBP by 0.7 mm Hg (95% CI: 0.4-1.0) over a mean follow
up of 2 years. One of six participants without hypertension (16.2%) at baseline developed
hypertension during the 2 year follow-up period. The overall age and non-response rate
adjusted incidence rate was 82.6 per 1000 person-years (95% CI: 80.8-84.4), whereas the
incidence rate adjusted only for non-response rate was 74.6 per 1000 person-years (95% CI:
70.5-79.1) (Table S6 and Table 2). Age adjusted incidence was highest in Delhi (94, 72 and 69
per 1000 person years of follow-up in Delhi, Chennai and Karachi, respectively). Nearly 9 of
10 incident cases (87.9%) were detected at the time of second year survey. Overall, there
were no differences in the incidence of hypertension in men and women (Fig 2). The
incidence of hypertension, however, was lower in women than in men in the younger age
group (<55 years), but was higher in women than men in the older age group (>55 years).
Incidence of hypertension was more than two times higher in participants with pre-
hypertension in all age groups at baseline than those with normal blood pressure (Figure
Predictors of incident hypertension
Hypertension incidence was similar in men and women (adjusted RR=1.08, 95% CI: 0.92-
1.26) in the multi-variable regression model. Hypertension incidence rate was positively and
linearly associated with age, and inversely and linearly associated with educational status
(Table 2). Overweight (BMI≥25.0 kg/m2) was associated with 28% higher incidence of
hypertension than those with BMI 18-23 kg/m2 (RR=1.28; 95% CI: 1.04-1.59). Current
alcohol use was associated with a 34% higher risk of hypertension relative to non-drinkers
(RR=1.34, 95% CI: 1.10-1.62). Presence of dysglycemia at baseline was associated with
higher incidence of hypertension (RR for diabetes=1.27, 95% CI: 1.05-1.53 and RR for pre-
diabetes=1.12; 95% CI: 0.96-1.32) in comparison to participants with normal glycemic levels.
Incident hypertension was three times higher (RR=2.95, 95% CI: 2.53-3.45) in individuals
with pre-hypertension at baseline in comparison to individuals with normal BP. Regression
results were comparable in the complete case analyses and in the analyses with imputed
missing covariates at baseline (Table 2). Collectively, 4 modifiable risk factors (pre-
hypertension, overweight, dysglycemia, and alcohol use) accounted for 78%% of the
population attributable risk of incident hypertension (Table S7).
Based on population-based data from adults over 20 years of age from three large cities in
South Asia, we estimated that on an average, one of three men and one of four women
have hypertension. Hypertension awareness, treatment, and control are alarmingly low.
Among non-hypertensive subjects, one of six adults developed hypertension over a two year
period, probably the highest incidence reported in the world. Propensity to develop
hypertension was higher among older, low socio-economic status participants, current
alcohol users, and individuals characterized as overweight, pre-hypertensive and
dysglycemic. The rate of progression from pre-hypertension to hypertension is three times
higher than that of individuals with normal BP.
Our study findings on prevalence, awareness, and treatment of hypertension are consistent
with previously reported data from the Indian sub-continent [6, 19, 20]. The incidence of
hypertension among one of six adults over a two year period is a great cause of concern. It
was significantly higher than the incidence data reported from developed countries [21, 22].
In absolute terms, this translates to more than doubling of the prevalence of hypertension
(assuming that the same rate continues for a decade) in a span of ten years with a
corresponding 243% and 271% increase among men and women, respectively. Our findings
imply that the previous estimates by Kearney and colleagues on the prevalence of
hypertension by 2025 (25% increase) is probably an under-estimate . The anticipated
increase in hypertension prevalence, in concurrence with a projected increase in prevalence
of diabetes in this population , will lead to dramatic rises in the incidence of
We report that the risk for progression to hypertension in this population is associated with
several socio-demographic (age, and educational status) and biological factors (overweight,
blood pressure levels, and dysglycemia). Unlike the previous studies where they had used
prevalent hypertension [24, 25], the outcome variable in our analyses was incident
hypertension, confirming temporality of association. Some findings of public health
significance are that the incidence of hypertension in individuals with pre-hypertension is
more than three times than in those with normal BP, and furthermore, it is considerably
higher in older age groups. Even at younger age groups, hypertension incidence risk is
significantly higher in individuals with pre-hypertension than in those with normal BP. Risk
stratiﬁcation and targeted preventive strategies among non-hypertensive persons who are
at greatest risk for progression to hypertension may help prevent the rapid rise in
prevalence of hypertension.
Although the overall incidence of hypertension was similar in men and women, the pattern
was distinctly different in older and younger age groups. The advantage women had in the
younger age group is completely offset by higher incidence of hypertension in the older age
group in comparison to men. This may be due to changes in the level of endogenous sex
hormones in the post-menopausal age group as they are associated with greater
longitudinal rise in BP . The predilection of hypertension was 28% higher in participants
above the BMI of 25 kg/m2, in comparison to individuals with BMI of 18-22.99 kg/m2, after
adjustment of the effect of waist circumference and other potential confounding variables.
However, it was similar in individuals with BMI of 23-24.99 kg/m2 and in individuals with
BMI of 18-22.99 kg/m2. This implies that the overweight cut-off of BMI>23 kg/m2 as
suggested by some of the authors  are probably not relevant for hypertension risk
stratification in South Asian settings.
The susceptibility to develop hypertension is higher in lower educated groups. These
findings affirm our previous observations [28, 29] and is in contrast to the opinion expressed
by a selected group of authors that non-communicable diseases and their risk factors are
not a problem in poor communities . The social gradient in hypertension has profound
implications for the countries and the health care system in south Asia. As described in our
study, a large majority of the incident hypertension remain undiagnosed in the absence of
regular surveillance. They are more likely to result in complications of hypertension. Even if
they are identified earlier, the probability of receiving treatment will be relatively low
especially among individuals in the low socio-economic strata. Further it is well-established
that majority of patients with hypertension will require 2 or more drugs to achieve BP
control . In this context, the high incidence rate of hypertension will also have huge
financial implications for drug requirements. With families and individuals spending a
significant proportion of their income for health care in South Asian countries especially in
the lower socio-economic strata, the impact of the rising prevalence of hypertension on
household economy is substantial.
Strengths and limitations
Prevalence and incidence estimates based on representative population-based sample from
three large cities in South Asia, standardized measurement techniques, uniform study
protocol and estimates after accounting for the complex study design are the major
strengths of the study. The response rate in the baseline and follow-up surveys are very
high. The incidence estimates are also adjusted for relatively lower non-response rate in the
follow-up surveys. Finally, generalizability of our findings is limited to adult men and women
living in metropolitan cities in the Indian sub-continent.
Sources of funding
This project has been funded in part by with Federal funds from the United States the
National Heart, Lung, and Blood Institute (NHLBI), National Institutes of Health (NIH),
Department of Health and Human Services, under contract no. HHSN268200900026C; and
the UnitedHealth Group, Minneapolis, MN, USA. Several members of the research team at
PHFI, Emory University, All India Institute of Medical Sciences, Aga Khan University and
Madras Diabetes Research Foundation were/are supported by D43 NCDs in India Training
Program through Award Number D43HD05249 from the Eunice Kennedy Shriver National
Institute of Child Health & Human Development (NICHD) and Fogarty International Center;
and the Wellcome Trust (Grant No: 096735/B/11/Z). Panniyammakal Jeemon is currently
supported by a Wellcome Trust-DBT India Alliance Clinical and Public Health Intermediate
Acknowledgement of grant support: This project has been funded in part by with Federal
funds from the United States the National Heart, Lung, and Blood Institute (NHLBI), National
Institutes of Health (NIH), Department of Health and Human Services, under contract no.
HHSN268200900026C; and the UnitedHealth Group, Minneapolis, MN, USA.
Potetial conflicts of interests: None to declare
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Figure 1: Prevalence, awareness, treatment and control of hypertension in adults over 20-
years of age in three South Asian cities. The denominator for awareness, treatment and
control are all individuals with hypertension at baseline.
Figure 2: Incidence of hypertension stratified by age groups in men and women. Incidence
rate is given per 1000 person years of follow-up.
Table 1. General characteristics of the study population
Socio economic status, %
ES1=educational status (above graduates), ES2=secondary school education, ES3=primary school and above, ES4=lower than primary or no
formal education or illiterates. High is third tertile, medium is second tertile, low is first tertile in the principal component analysis score.
Table 2: Incidence of and risk factors for hypertension
incidence rate per
1000 p-y (95% CI)
per 1000 p-y
Unadjusted RR, CI
Adjusted RR, CI
1.23* [1.05, 1.45]
Age groups, years
1.37 [0.94, 2.00]
1.05 [0.92, 1.21]
1.13 [0.95, 1.34]
1.14 [0.95, 1.36]
1.23* [1.02, 1.49]
0.82 [0.60, 1.12]
1.10 [0.91, 1.34]
1.25* [1.03, 1.52]
Waist circumference , cm
1.06 [0.90, 1.27]
1.09 [0.95, 1.26]
Current alcohol use
0.96 [0.80, 1.15]
1.03 [0.86, 1.23]
1.22* [1.03, 1.44]
1.09 [0.95, 1.26]
Parental history of hypertension
1.10 [0.93, 1.29]
eGFR , ml/min/1.73 m2
Baseline blood pressure levels , mmHg
1.18* [1.04, 1.35]
*p<0.05, **P<0.01, ǂp<0.001, RR=relative risk ratio, ∏Adjusted for uneven response rate in different risk groups, Ⱡmodel includes serum
creatinine based eGFR measurements from Delhi and Chennai (data are not available in Karachi). p-y=person years, ci=confidence interval,
eGFR=estimated glomerular filtration rate, BMI=body mass index, ES1=educational status (above graduates), ES2=secondary school education,
ES3=primary school and above, ES4=lower than primary or no formal education or illiterates.