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African Journal of Biomedical Research
Ibadan Biomedical Communications Group
ISSN: 1119-5096
Vol. 6, Num. 3, 2003, pp. 129-132
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African Journal of Biomedical Research, Vol. 6, No. 3, Sept, 2003,
pp. 129-132
PREVALENCE OF OBESITY AND HIGH LEVEL OF CHOLESTEROL IN HYPERTENSION: Analysis
of Data from the University College Hospital , Ibadan
YEKEEN L.A, SANUSI R.A AND KETIKU A.O*
Department of Human Nutrition, College of Medicine University
of Ibadan , Ibadan .
* Author for correspondence
Received: January 2003
Accepted in final form: June 2003
Code Number: md03053
This study was undertaken to determine what proportion of patients with
hypertension are obese and or have elevated serum cholesterol. The data of
two hundred and fifty patients who attended the outpatient clinics of the
University College Hospital, Ibadan from January 1998 to December 2001 were
analysed. Almost half of the subjects (48.8%) had mild, 40.8% moderate, and
8.8% severe hypertension. While mild hypertension was more in the females
(55.4%), moderate and severe hypertension was more among males. Among the
subjects that were overweight (BMI>25<30), 44% were males and 56% were
females. There were more obese (BMI>30) among the females (63.6%) than
the males (36.4%). Only 166 of the subjects had serum cholesterol analysis,
and only 9.6% had a hyper-cholesterol (>240mg/dl) level. Obesity and hyper-cholesterol
and hypertension are known risk factors in cardiovascular diseases. Since
weight reduction has been noted to reduce severity of hypertension, this
should be a cost effective intervention in both the control of hypertension
and lowering the risk of coronary heart diseases.
Keywords: hypertension, obesity, serum cholesterol. Running
title: prevalence of obesity in hypertension.
INTRODUCTION
Obesity and high blood cholesterol have been identified as risk factors in
hypertension (Jones and Davis 1992). People with hypertension are also more
likely to have lipid abnormality and obesity than those with normal blood pressure
(Wannarinthee et al 1998). Furthermore blood pressure is strongly related
to body weight and control of obesity is a critical component of prevention
and control of hypertension (Kummayinka 1997). Clinical trials have also suggested
a reduction in the incidence of coronary heart disease by lowering serum cholesterol
levels.
Although the population prevalence of obesity and hypertension is not known,
a country-wide survey in Nigeria in 1990-91 put the prevalence of hypertension
at 11.2% in those older than l5years old (Mabadeje, 1999). Hypertension is
the most important of the known risk factors of cardiovascular disease (Sokolow,
Mcllroy and Roberts 1975).
Since each of these conditions is associated with appreciable morbidity and
mortality, and they may occur together increasing the associated complications,
this study was undertaken to determine the percentage (or proportion) of patients
with hypertension that are obese or have hypercholesterolemia or both. As dietary
control and exercise can influence obesity and high cholesterol level, these
may become more prominent in the management of hypertension. This is because
epidemiologic studies have suggested that 70% of elevated blood pressure is
due to environmental factors, prominent among which is weight gain (Pickering,
1968).
The general objective of this study was to determine the proportion of patients
with hypertension who are obese and who also have high blood levels of cholesterol.
METHODOLOGY
This study was descriptive, cross-sectional and retrospective in design. The
location of the study was the medical outpatients (MOP) clinic of the University
College Hospital (UCH), Ibadan, Nigeria. This is the oldest teaching Hospital
in Nigeria with an outpatient population of over 200,000 per year (Ajayi, 1997).
Subjects of the study were hypertensive patients who were attending MOP clinic
for medical treatment. The selection criterion was open and it included all
hypertensive patients that had attended that clinic between January 1998 and
December 2001. The sampling technique adopted was purposive. Incomplete data
in the patient's records was the exclusion criterion. Two hundred and fifty
(250) patients who received treatment from January 1998 to January 2001 and
had adequate records, constituted the study sample.
Data was extracted from individual case notes, which were retrieved from the
medical records department after all issues of ethical clearance had been adequately
satisfied. Extracted data included; age, gender, weight, height, blood pressure
on the first visit and total cholesterol in blood. Body mass index (BM1) was
derived from weight and height measurements. Data analysis was performed using
the statistical package for social sciences (SPSS) for window version 7.5.
Main analysis included descriptive statistics; however relationships were explored
using cross-tabulations, correlation and linear regression.
RESULTS
A total of two hundred and fifty subjects were studied; One hundred and two
(40.8%) were males, while one hundred and forty eight (59.2%) were females.
The mean age was 48 (± 9.1) yrs. and mean BMI 28.6 (±4.1) as
shown in Table 1. The profile of severity of hypertension and gender (Table
2) showed the prevalence of mild hypertension to be higher in females while
moderate and severe hypertension were more in males.
Table 1: Characteristics of Subjects and Gender
|
MALES |
FEMALES |
|
N |
Mean |
SD |
N |
Mean |
SD |
Age (yrs) |
102 |
48.2 |
9.1 |
148 |
47.6 |
9.1 |
BMI(kg/m 2 ) |
102 |
27.9 |
3.2 |
148 |
29.1 |
4.6 |
Cholesterol (mg/dl) |
77 |
209.8 |
44.4 |
89 |
208.6 |
29.2 |
Diastolic BP (mmHg) |
102 |
108.5 |
13.5 |
148 |
105.5 |
12.8 |
Systolic BP (mmHg) |
102 |
173.5 |
19.7 |
148 |
171.5 |
17.5 |
Table 2: Gender, Obesity and Hypertension
|
MALES |
FEMALES |
Hypertension |
n |
% |
n |
% |
Mild DBP>90mmHg |
40 |
39.2 |
82 |
55.4 |
Moderate DBP>l05mmHg |
47 |
46.0 |
55 |
37.2 |
Severe DBP> 130mmHg |
12 |
11.8 |
10 |
6.7 |
Obesity |
n |
% |
n |
% |
Overweight (BMI 25-29.9) |
60 |
58.8 |
76 |
51.4 |
Grade 2 obese (BMI 3 0-39.9) |
28 |
27.5 |
49 |
33.1 |
Grade 3 Obese (BMI >40) |
0 |
0.0 |
5 |
3.4 |
Non-Obese (BMI 18.5-24.99) |
12 |
11.8 |
16 |
10.8 |
This difference is statistically significant at p<0.05. Among the males
40 (39.2%) had mild hypertension, while 47(46%) had moderate hypertension
and 12 (11.4%) had severe hypertension. Among the females, while 82 (55.4%)
had mild hypertension, 55 (37.2%) had moderate hypertension and 10 (6.7%) had
severe hypertension. This result suggests that except in the mild hypertension
category, there are more males in the moderate and severe categories of hypertension.
There are also more who are overweight (BMI>25<30) among the males (59%)
than in females (51%). However grade 2 obesity (BMI>30<40) is more in
females (33%) than in males (28%). The non-obese are about equal among the
males (11.8%) and females (10.8%). Only 166 of the subjects bad serum cholesterol
estimation and among these 26 (34%) males and 27 (30%) females had a desirable level
of less than 200mg/dl (National Cholesterol Education Program, 1988). In the borderline (serum
cholesterol level of > 200 < 240mg/dl) category, 42 (43%) were males
while 55 (57%) were females. Among the 16 that had high level of serum cholesterol
(hyper-cholesterol), 9 (5 6%) were males while 7 (44%) were females. The proportion
of patients having hyper-cholesterol in the study is low (9.6%). These are
shown in Table 3.
A brief summary of the interface between obesity and hypertension shows that
majority (50%) of those with mild and moderate hypertension are in the overweight
category (BMI > 25 < 30). Also greater proportion of females in grade
one (BMI > 25 <30) and two (BMI > 30 < 40) obesity, had mild hypertension
while greater proportion of males in similar categories of obesity had moderate hypertension
(Table 4).
Table 3: Cholesterol profile of Obese Hypertensives
Serum Cholesterol |
MALE |
FEMALE |
n |
% |
n |
% |
Desirable |
26 |
33.8 |
27 |
30.3 |
Borderline |
42 |
54.5 |
55 |
61.8 |
High |
9 |
11.7 |
7 |
7.8 |
Total |
77 |
100 |
89 |
100 |
Desirable = <200mg/di
Borderline= >200<240mg/di
High > 240mg/di
(National Cholesterol Education Programme 1998)
DISCUSSION
The population specific prevalence of hypertension in Nigeria is not known
with certainty. However in a countrywide survey in 1990-1991 Mabadeje (1999)
reported a rate of 11.2% in those aged 15 years old and above. Olatunbosun et
al (2000) in a study of urban-based civil servants in Ibadan found the
prevalence of hypertension to be 10.3%, although this was higher in men (13.9%)
than in women (5.3%). Similarly, the prevalence of hypertension in the elderly
whose ages were over 55years was 30% (Ezenwaka et al 1997). Okesina et al (1999)
also observed a prevalence of 15.2% hypertension in Maiduguri with a rate of
19.1% in males and 10.3% in females. The degree of hypertension varies among
the sexes. This study shows that while there was more of the mild hypertension
in the females (55.4%), more of the moderate and severe categories occur in
men. Lack of categorization of the degree of hypertension limits easy comparison
with previous studies. Cooper et al (1997) had reported a hypertension prevalence
of 16% in West Africa and had implicated obesity and dietary intake of sodium
and potassium.
While overweight category was higher in males (5 8.5%) than in females (51.3%),
grade two obesity was more in the females (33%) than males (27%). These differences
were statistically significant (pet al 2000, Okesina et al 1999).
Okesina et al (1999) had reported an overall prevalence of obesity
to be 2% in the Maiduguri study with a higher 3.2% in females and 1.2% in males.
The percentage of subjects whose BMI was> 30 in this study was 33% in females
and 27.4% in males. Okosun et al (1999) had suggested that the prevalence
of hypertension was closely linked to abdominal adiposity; however since waist-hip
ratio was not measured in this study, it is difficult to confirm their observation
with the findings of the present study. Ezenwaka et al (1997) had also
reported a higher prevalence of obesity and high blood pressure in women and
in urban settings. Hyper-cholesterol was found in 5.4% of the men and 4.2%
of the females in this study.
Table 4: Hypertension severity and Obesity category
HYPERTENSION
CATEGORY |
Obesity Category
|
Males |
Females |
Mild (%) |
Moderate (%) |
Severe(%) |
Mild (%) |
Moderate(%) |
Severe(%) |
Overweight (BMI 25-29.9) |
23 (22.5) |
29 (28.4) |
6 (5.9) |
45 (30.4) |
29 (19.6) |
2 (1.4) |
Obese
(BMI > 30) |
09 (8.8) |
14 (13.7) |
5 (4.9) |
28(18.9) |
19 (12.8) |
07 (4.7) |
|
32 |
43 |
11 |
73 |
48 |
09 |
Okesina et al (1999), had found a zero % when hyper-cholesterol was defined
as a level greater than 206.7mgldl, however the criterion for this study is
serum cholesterol level greater than 240mg/dl (National Cholesterol Education
Programme 1998). As the prevalence of hypertension in several population studies
has overshot the 10% trigger- point, it is necessary to activate intervention
to lower this rate. The control of dietary energy intake, sodium consumption
and inactivity are areas of potential interventions. So far the prevalence
of coronary heart disease is still low in Africa; paradoxically the risk factors
of hypertension, obesity and high serum cholesterol associated with coronary
heart disease are emerging.
As exploration of effect of obesity categories on severity of hypertension
showed that while prevalence of obesity (BMI> 30) is almost twice as high
in females than in males, prevalence of moderate hypertension is higher in
males than in females. It is safe therefore to suggest that except in severe
hypertension, obesity and hypertension are highly associated.
The importance of this finding is to enable care-givers in hypertension
pay more attention to the control of obesity so that several complications
associated with it might be prevented. The risk factors of coronary heart disease
(CHD) already seen in several of the obese patients can be lowered by dietary
intervention, as well as other medical control of hypertension. It is clear
that the population prevalence of obesity, hypertension and hyper-cholesterol
if known will be useful in planning interventions.
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