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MC Vol. 19 - No.4 - 2013 ( 5 - 8 ) Saeed S. et al
Quarterly Medical Channel www.medicalchannel.pk
RELATIONSHIP BETWEEN BMI AND BLOOD
PRESSURE AMONG STUDENTS OF 3
RD
YEAR
AT INSTITUTE OF MEDICAL TECHNOLOGY
(DUHS)
ABSTRACT:
Introduction: Hypertension, an illness that develops as a result of high blood pressure,
is intensely related with body mass index (BMI). Obesity has been distinguished to be
single best predictor and major controllable contributor of incidence of hypertension.
Objective: To evaluate relationship between BMI and Blood Pressure among students of
3rd year at (IMT) Institute of Medical Technology (DUHS)
Design: Cross sectional study.
Methodology: A total of 320 students, 163 males and 157 females participated in the study
conducted between December 2011 and May 2012 at (IMT) DUHS. All students were
divided into underweight, normal, over weight and obese category according to World
Health Organization (WHO) BMI classification. Hypertension was determined from the
measure of Blood pressure (BP). Comparison of blood pressure among different groups
was made by ANOVA.
Results: Among students 10.6 % were overweight (BMI: 24.9 to 29.9) and 2.2 % were
obese (BMI of >30) while rest had a normal BMI. Their mean age was calculated to be
21.4 years and height 1.68 meters. A consistent increase was seen in the prevalence of
hypertension in: normal, over weight and obese category i.e. 3%, 47% and 85% respectively.
Mean values of systolic BP (104.66, 136.47, 150 mmHg) and diastolic BP (69.93, 92.94,
100 mmHg) also increased with increasing BMI. The prevalence of cardiovascular symptoms
was higher at BMI levels above 24.9 but did not increase consistently with increasing
BMI.
Conclusion: The prevalence of high blood pressure was observed with increasing BMI
among students.
Key words: Blood pressure, Overweight, Obesity
INTRODUCTION:
Hypertension (HTN) is a medical condition in which the blood pressure is chronically
elevated.1 It is usually found incidentally by healthcare professionals measuring blood
pressure during a routine checkup. In isolation, it usually produces no symptoms although
some people do report symptoms during onset or before hypertension is diagnosed.2 Although
no specific medical cause can be determined in essential hypertension, it often has several
contributing factors which include obesity, salt sensitivity, renin homeostasis, insulin resistance,
genetics and age. It is also strongly correlated with BMI.3 The risk of hypertension is
five times higher in the obese as compared to those of normal weight and up to two-thirds
of the obese cases can be attributed to excess weight. More than 85% of cases occur in
those with a BMI>25.4 Literature suggests that diastolic blood pressure intervention alone
may avert one million deaths per year throughout Asia. Increased blood pressure is a very
important public health issue with prevalence of 15% in different parts of world. In Pakistan,
MEDICALMEDICAL
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Original Article
1. SUMMAYA SAEED
FCPS (Surgery), MBBS (Dow),
CRCP (DUHS)
2. AUN ALI
FCPS (Surgery), MBBS (Dow),
CRCP (DUHS)
3. RABEL KHAWAJA
MPH (UK), MBBS (PAK)
4. IRFAN ALI SHAIKH
FCPS (SURGERY), MBBS (PAK)
5. IRFANULLAH SHAH
FCPS (NEURO SURGERY), MBBS
(DOW), CRCP (DUHS)
6. MOHAMMAD WAJEEH
MUSTAFA
7. MUNAZZA MUSTAFA
OCTOBER - DECEMBER 2013
Correspondence:
DR. SUMMAYA SAEED
summayasaeed@hotmail.com
03002820774
15/N Block 6, P.e.c.h.s. Karachi.
Pakistan.
1. Registrar General Surgery,
Surgical Unit V, DUHS and CHK
2. Assistant Professor General
Surgery,
Jinnah Medical And Dental
College, Karachi
3. Instructor Research,
Department Of Obstretrics &
Gynaecology
The Agha Khan University Karachi
4. Assistant Professor General
Surgery,
Jinnah Medical And Dental
College, Karachi
5. Spine Fellow, King Fahad Medical
City (KFMC), Riyadh KSA
6. Critical Care Medical Technologist
DUHS
7. Physical Therapy Trainer Liaquat
National Hospital, Karachi.
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MC Vol. 19 - No.4 - 2013 ( 5 - 8 ) Saeed S. et al
Quarterly Medical Channel www.medicalchannel.pk
circulatory diseases cause more than 12% of all death per year and
there are 5.5 million males and 5.3 million females who are reported
as hypertensive.5 Pakistan health demographic survey 2006-07 shows
that excessive body weight is important cause of hypertension and
achieving a desirable bodyweight is one of the non-pharmacological
therapies, which helps controlling hypertension.6
Obesity is defined as an unnecessary accumulation of fat in the
body resulting in increase in weight beyond that considered desirable
with regard to age, height and weight. This deposition of fat could
be generalized or may occur preferentially in different adipose tissue
compartments.3 It has become major public health issue not only
in developed world but is also affecting the developing countries
like Pakistan.Compared to the developed countries, the developing
countries are at higher risk of the disease related to overweight,
and cardiovascular diseases have grown to be the major cause of
morbidity and mortality in developing world.7 National survey of
Pakistan in 2001 showed 25% of the population as over-weight
according to the Asian-specific BMI cut-off values and 10.3% as
obese, which confirms obesity to be a growing public health issue
in the country.8 Evidence has shown that approximately 30% - 60%
of hypertensive patients are at risk of obesity in males below the
age of 45 years and gaining weight itself is a risk factor of
hypertension.3
Obesity and hypertension both are common health problems in
children, young as well as adults. Recently in 2013 there is the
study done in China which shows, there is strong positive relationship
between BMI and BP in 12 year old children.9 Literature from different
countries has also shown that obesity is associated with high blood
pressure in children as well as adults, those who are obese are at
more risk of hypertension as compared to thin lean people.10 Present
study is focusing on relationship between BMI and blood pressure
in student population of 3rd year in DUHS, Karachi, as in our part
of the world hypertension is considered the disease of older population
and usually most of the studies are conducted are directed towards
the elderly age group, leaving lack of data regarding prevalence
of hypertension among the student population and awareness of
its presence among them. The objective of the study was to evaluate
relationship with reference to predicted normal values and to quantify
the student population in need of treatment for hypertension.
SUBJECTS AND METHODS:
This cross-sectional study was conducted on 3rd year students of
DUHS (IMT) between Dec 2011 and May 2012; after being granted
approval from the ethical committee of DUHS. 320 students, who
participated voluntarily, were screened through a medical history
questionnaire, physical examination, blood pressure and physical
activity. After taking written informed consent, data was collected
through structured questionnaire. The measurements of blood pressure
were taken through pre-checked and reliable apparatus i.e. mercury
sphygmomanometer. The students were seated calm and quiet for
at least 5 minutes prior to measurement on comfortable chairs. For
categorization of blood pressure WHO classification was used
according to which students having blood pressure of 140/90 mm
Hg were labeled as hypertensive.10 Three consecutive readings of
BP were recorded in morning at the interval of 3 minutes between
consecutive measurements in sitting position on three alternate days.
Participants were asked if they were taking any medications for
the treatment of hypertension or obesity. Weight and height were
measured with subjects standing without shoes and wearing light
clothes. Students stood upright with the head in Frankfort plane
for height measurement. Height was recorded to the nearest 0.5
cm and weight was recorded nearest 100g. BMI was then calculated
through standard formula i.e. weight (kg)/height (m2). Data was
entered in SPSS version 16.0. Descriptive analysis of BP, weight,
height and BMI were calculated. Comparison of BP among BMI
groups was made by ANOVA also keeping in view gender distribution
in each. P – value of < 0.005 was taken significant.
RESULTS:
Demographics & BMI:
Baseline characteristics showed that the mean age of the students
was 21.4 years (range 20-23 years) (Table 1). These included 163
(50.9%) males and 157(49.1%) females (male to female ratio. 1.04:
1). 50% of the candidates were < 1.7 meters in height with a mean
height of 1.68 meters. The weight was calculated in kilograms and
27.5% of the students weighted 75 kg and the mean weight of the
study group was found to be 67.1 kg. BMI was categorized according
to WHO classification into 4 categories i.e. underweight <18.5, Normal
weight 18.6 – 24.9, Over weight 25 – 29.9 and Obese > 30. None
of the candidates fell in underweight category hence it was not included
RELATIONSHIP BETWEEN BMI AND BLOOD PRESSURE AMONG STUDENTS
TABLE 1:
Baseline Descriptive Characteristics of the Participants
OVER ALL (N=320)
AGE IN YEARS
20 42(13%)
21 133(42%)
22 115(36%)
23 30(9%)
GENDER
Male 163(50.9%)
Female 157 (49.1%)
HEIGHT IN METERS
1.584 56 (17.5%)
1.645 69(21.6%)
1.706 96(30%)
1.767 49(15.3%)
1.798 48(15%)
1.828 2(0.6%)
WEIGHT IN KG
55 50(15.6%)
60 46(14.4%)
65 70(21.9%)
70 50(15.6%)
75 88(27.5%)
80 15(4.7%)
140 1(0.3%)
BMI CATEGORIES
18.6 - 24.9 279(87.2%)
25 - 29.9 34(10.6%)
>30 7(2.2%)
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MC Vol. 19 - No.4 - 2013 ( 5 - 8 ) Saeed S. et al
Quarterly Medical Channel www.medicalchannel.pk
that there is strong association between BMI and SBP or DBP in
male and female students. Tassaduq et. al, found the increased
prevalence of hypertension with advancing age.5 Whereas, Humayun
et al. indicated strong association of hypertension to BMI rather
than age.3 Tesfaye et. al conducted study in Asia and Africa in 2006
found that SBP and DBP were positively correlated with age while
BMI was not or was negatively correlated in some cases.11 The
findings of present study are similar to the study done by Huang
et. al, showing that females in overweight BMI category indicates
a significant prevalence of hypertension than their male counterparts
in similar category.12 However, our results of female students were
not consistence with the findings of Tassaduq et, al.5 There are
several causes attributable to this change in results of hypertension
in female students, the confounding factor being selection of age.
The prevalence of both hypertensionandobesity is a significantpublic
health challenge and its trend is increasing throughout the world.
As comparedto the year 2000, the number of hypertensive patients
isexpected to rise by 60% by theyear 2025.13 This huge increase
in prevalence of obesityis welldocumented as one of the major risk
factors for theprogress ofhypertensionwhich might be due to their
sedentary life style or eating habits of the population specially students.
During our daily observation, we can say that students are more
addicted to junk foods specially burgers and cold drinks which are
common causes of obesity and the results of present study are
consistent with this hypothesis.
The results of present study enumerate the strong relation of BMI
with hypertension and cardiovascular symptoms. They are constant
with the nationwide importance on prevention as well as control
of weight and obesity. They also specify that measurement of blood
in the analysis. Out of 320 students, 2.2% were obese (BMI >30),
10.6 % were overweight (BMI of 24.9 to 29.9) and 87.2 % had
normal weight. (Table 1)
Gender Distribution and Hypertension:
157 male and 130 female candidates fall in normal weight category,
whereas, in overweight and obese category, female candidates were
more in number. 21 females as compared to 5 male students belong
to overweight category while in obese class there was only one
male student and 6 females. (Table 2)
Relationship between BMI and Blood Pressure:
The prevalence of high blood pressure in normal, over weight and
obese category was 3%, 47% and 85% respectively (Table 3). Mean
values of systolic (104.66, 136.47, 150mmHg) and diastolic BP (69.93,
92.94, 100 mmHg) were found to be higher as the BMI increased
(Table 4). The associations of BMI with cardiovascular symptoms
were statistically significant in obese and overweight category as
compared to normal weight category P – value < 0.0005.
DISCUSSION:
Hypertension possesses an unnecessary economic burden on the
people and health systems; which consumes scarce resource hence
for it management preventive approaches might be cost effective.
The expenses we are paying for comfortable and urbanized society
is an inactive life style and unhealthy dietary habits which result
in difference between energy consumption and expenditure which
in turn leads to obesity.3 The present study comprised of random
sample of male and female students selected on the criteria based
on being healthy (with no known comorbid). The results indicate
TABLE 4-
Mean BP in each BMI Category
Body mass index Mean Systolic BP Mean Diastolic BP
18.6 - 24.9 104.66 69.93
25 - 29.9 136.47 92.94
>30 150.00 100.00
RELATIONSHIP BETWEEN BMI AND BLOOD PRESSURE AMONG STUDENTS
TABLE 2-
Sex * Body mass index Cross tabulation
Body mass index Total
18.6 - 24.9 25 - 29.9 >30
Sex Male 157 5 1 163
Female 130 21 6 157
Total 287 26 7 320
TABLE 3-
Hypertension* Body mass index Cross tabulation
Body mass index Total
18.6 - 24.9 25 - 29.9 >30
Hypertension Yes 9 16 6 31
No 270 18 1 289
Total 279 34 7 320
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MC Vol. 19 - No.4 - 2013 ( 5 - 8 ) Saeed S. et al
Quarterly Medical Channel www.medicalchannel.pk
pressure and body weight and timely diagnosis and control are
exclusively essential for overweight and obese people. Hypertension
is directly associated to BMI, it shows that increase in BMI leads
to increase in the trend of hypertension in both male and female
students. In normal BMI category, fairly increased percentage of
male students showed the signs of hypertension however, in overweight
class, hypertension is high among female candidates. The current
study only focused on students so the diverse age groups were not
included and weight history and effect of weight change on
hypertension were not focused upon. Therefore, we cannot assume
from our data how the ideal weight should be attained. Hypertension
is more common in over weight and obese class in both male and
female students.
CONCLUSION AND RECOMMANDATIONS:
The prevalence of high blood pressure and mean levels of systolic
and diastolic blood pressure increase as BMI increases. The students
who are obese should have timely intervention for reducing their
weight and hence decreasing chances of hypertension. Also they
should be closely monitored so as to pick the disease in early stages
and get standard treatment accordingly.
Conflict of interest: Authors express no conflict of interest.
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RELATIONSHIP BETWEEN BMI AND BLOOD PRESSURE AMONG STUDENTS
