|
|
|
Indian Pediatr 2010;47: 873-876 |
 |
Prevalence of Hypertension Among
Schoolchildren in Shimla |
|
Avinash Sharma, Neelam Grover, Shayam Kaushik, Rajiv
Bhardwaj and Naveen Sankhyan*
From Indira Gandhi Medical College, Shimla, Himachal
Pradesh; and *Department of Pediatrics, All India Institute of Medical
Sciences, New Delhi.
Correspondence to: Dr Avinash Sharma, Department of
Pediatrics, Rajendra Prasad Government Medical College, Tanda, Kangra,
Himachal Pradesh 176 001, India.
Email: [email protected]
Received: May 29, 2009;
Initial review: July 1, 2009;
Accepted: October 6, 2009.
Published online: 2010
January 15.
PII: S097475590900381-1
|
|
Abstract
This cross-sectional study was done to find the
prevalence of sustained hypertension and prehypertension among school
children aged 11-17 years. A total of 1085 apparently healthy students
from rural and urban schools in hills of northern India were examined
using standard methods. Students with blood pressures above the 90th
centile were re-examined after four weeks. The mean BMI of the students
was 17.5±2.7 kg/m2, 5 (0.4%) were obese, and 39 (3.5%) overweight. After
two evaluations, hypertension was identified in 62 (5.9%) children and
prehypertension in 130 (12.3%). Urban and rural children had comparable
rates of elevated BP (hypertension and prehypertension). Rates of
elevated BP were significantly higher (46.5% vs 17%, P<0.001)
among those with high BMI (overweight and obese) compared to those with
normal BMI. In conclusion, nearly 20% of the school children had
elevated blood pressures.
Keywords: Blood pressure, Body mass index, India, Obesity,
Prehypertension.
|
|
H
ypertension is a major public
health problem worldwide and is one of the risk factors for coronary
artery disease and cerebrovascular disease. Development of adult
hypertension may start very early in life, and children maintain their
position in the blood pressure distribution over time(1). As the symptoms
of childhood hypertension are largely nonspecific, most children with
essential hypertension are likely to be asymptomatic(2). The data on
prevalence of prehypertension and sustained hypertension in school going
children is scanty in India(3-7). The present study was designed to
determine the prevalence of sustained hypertension and prehypertension
among apparently healthy school children residing in the hills of northern
India.
Methods
This cross-sectional, school-based survey was carried
out from November 2005 to December 2006 by the Departments of Pediatrics
and Cardiology, Indira Gandhi Medical College, Shimla. The study was
approved by the institutional ethics committee. We enrolled children aged
11-17 years from both urban and rural schools in and around Shimla, which
is situated in the moderate altitudes of Himalayas (800-2000 m). After
obtaining informed consent from the parents, all children present on the
day of first contact in a particular school were enrolled. Those on
anti-hypertensive medication and known to have chronic heart, renal or
hepatic disease, and those who were absent on first day were excluded.
Information on age, sex and family history of hypertension and
cardiovascular disease was recorded. Family history was taken to be a
history of hypertension in the parents or the grandparents. Height and
weight were measured, using "Detecto" stadiometer (UNICEF) with beam
balance, with sensitivity of 0.1 cm and 0.1 kg, respectively. Zero error
was set after every 10 measurements. Body mass index (BMI) was calculated
and cut-off values for adolescents proposed by Cole, et al.(8) were
used for defining overweight and obesity. Before blood pressure
measurements, students were familiarized to the instrument and the nature
of the procedure was explained. Blood pressure was determined by
auscultation in right arm after a minimum rest of 30 minutes, by
standardized method using the mercury gravity sphygmomanometer(9,10). For
each student, the blood pressure was measured thrice in the same visit
with a minimum of 30 seconds rest between each determination and mean
blood pressure was calculated. The systolic blood pressure was deter-mined
by the onset of the "tapping" Korotkoff-1 sound and the diastolic at its
disappearance (Korotkoff-5). The children were considered hypertensive if
the systolic or diastolic blood pressure or both were equal to or more
than the 95 th percentile for height
for age and sex. Prehypertension was defined as systolic or diastolic
blood pressure or both between 90th and 95th percentile for height for age
and sex, or if the systolic blood pressure was more than 120 mm of Hg or
the diastolic blood pressure was more than 80 mm of Hg(9). Height for age
standards was determined using the CDC 2000 growth charts(11). Students
found to have hyper-tension or prehypertension on first visit were
contacted to undergo a second set of blood pressure measurements at least
four weeks later. Three further sets of reading were taken on second
contact, 4 weeks or later after the first measurement. The pre stated
norms were then used to conclude the presence or absence of hypertension
or prehyper-tension. All anthropometric and blood pressure measurements
were made by a single observer.
With an estimated prevalence of elevated blood pressure
(prehypertension and hypertension) at 0.1 and precision for upper and
lower 95% CI at ±0.02, the sample size required was 865. SPSS-15 software
was used for the analysis of data. Since the measurements were normally
distributed, mean and standard deviation were calculated for height,
weight, age, blood pressure and body mass index. Continuous variables were
compared using student-t test. Dichotomous variables were compared using
chi-square test; P <0.05 was considered significant.
Results
Of the 1085 students (570 boys) enrolled on first
contact, 518 (47.7%) were from rural schools (Table 1) and
30 students were not available for evaluation at the second contact.
Hypertension was significantly more prevalent among urban students
compared to rural students (7.1% vs. 4.3%, P=0.047). Among
62 students with hypertension, 19 (30.7%) had a family history of
hypertension. Significantly more urban children had a family history of
hypertension. The prevalence of hypertension was significantly higher in
those with a family history of hypertension (8.6% vs 5%, P=0.04).
The prevalence of prehypertension was significantly higher among rural
children (Table I). Among 39 overweight students, 10 had
hypertension and 7 had prehypertension. Among five obese students, two had
hypertension and one had prehypertension. Rates of elevated blood pressure
(prehypertension and hypertension) were significantly higher (46.5 vs
17%, P <0.001) among those with high BMI (overweight and obese)
compared to those with normal BMI.
TABLE I
Anthropometric Data and Blood Pressure Measurements
|
Variables |
Rural |
Urban |
Total |
| |
Boys |
Girls |
Total |
Boys |
Girls |
Total |
|
| |
(n=259) |
(n=259) |
(n=567) |
(n=311) |
(n=256) |
(n=567) |
(n=1085) |
| Prehypertension |
42 |
32 |
74 (14.3%)* |
29 |
27 |
56(9.8%) |
130(12.3%)† |
| Hypertension |
10 |
12 |
22 (4.3%)* |
17 |
23 |
40(7%) |
62(5.9%)† |
| Elevated blood pressure††
|
52 |
44 |
96 (18.5%) |
46 |
50 |
96(16.9%) |
192(18.2%) |
| Lost to follow up |
4 |
4 |
8 (1.5%) |
14 |
8 |
22(3.8%) |
30(2.7%) |
| Obese |
0 |
0 |
0* |
2 |
3 |
5(1%) |
5(0.4%) |
| Overweight |
1 |
3 |
4 (0.1%)*** |
15 |
20 |
35(6.2%) |
39(3.5%) |
| High BMI (Obese and overweight) |
1 |
3 |
4 (0.1%)*** |
17 |
23 |
40(7%) |
44(4%) |
|
* P <0.05, *** P <0.001 for rural vs urban using Chi square test. There were no significant differences between boys and girls, †- percentage calculated after exclusion of those lost to follow up,††- Elevated blood pressure includes those with hypertension and prehypertension; BMI: body mass index. |
Discussion
It is important to determine the prevalence of
hypertension and prehypertension in children, not only because it varies
from one community to the other(12), but also because it is essential to
identify the population at risk. Early identification translates into
early interventions and possibly prevention of later morbidity and
mortality(9). In the studied school children, 5.9% had hypertension and an
additional 12.3% had prehypertension. This reflects an alarming situation,
where overall almost 1 out of every 5 children needs some intervention as
guided by the Fourth Task Force recommendations(9).
The rates of high blood pressure in this study are
marginally higher than those reported in a recent survey in United States,
wherein 13.6% of boys and 5.7% of the girls aged 8-17 years were
classified as pre-elevated blood pressure and 2.6% of the boys and 3.4% of
the girls were having elevated blood pressure(13). In a large survey of
5641 Pakistani children aged 5 to 14 years, the overall prevalence of high
blood pressure was 12.2%. The authors observed that despite lower BMIs of
south Asian children, the prevalence of hypertension was substantially
greater than the 5% predicted prevalence of high blood pressure in
children in the United States based on same criteria(12). It is possible
that there exist different risk factors among children of South Asia.
Within India, regional differences in blood pressure among children older
than 13 yr of age were highlighted by Krishna, et al.(3). North
Indian boys and girls had significantly higher systolic blood pressure
compared with south Indian children.
In this study, on first evaluation, 31.3% of the
students were hypertensive, but on repeat measurement only 5.9% were
hypertensive. In the Muscatine study enrolling 6,622 students, 13% of
school children had hypertension when first examined, but on repeated
measurements less than 1% had their blood pressure in the hypertensive
range(14). Similar has been the observations of other resear-chers(4,15).
A more precise clinical estimate would include blood pressure measurements
on ³3
separate occasions. However, multiple readings of blood pressure from the
same day are considered appropriate for epidemiological studies(16).
We found significantly more urban students to have
hypertension and more rural children to have prehypertension. This could
be a chance finding, as the prevalence was comparable when hypertension
and prehypertension were combined, and viewed as elevated blood pressure.
In the study from Pakistan, similar high rates of hypertension were
observed among rural children(12).
The association between elevated blood pressure and
high BMI observed by us has been noted by various workers including few
from this part of the world(5,6,13,17). The Muscatine study
reported 56.1% out of 41 hypertensive subjects to be obese(14). Sorof,
et al.(15) also showed more prevalence of hypertension in obese
children as compared to non-obese (33% vs 11%). In a survey of two
schools catering to urban affluent high socio-economic class in Pune, the
prevalence of high systolic blood pressure was 12.0% in boys and 9.7% in
girls and increased with increasing levels of BMI, weight, triceps skin
fold thickness and percent body fat(7). Interestingly, our study showed a
high pre-valence of hypertension and prehypertension among students
despite a low prevalence of obesity.
There were some limitations of this study. All
measurements were made by a single observer, which may be a source of
bias. A third or fourth measurement of blood pressure could have possibly
lowered the number of hypertensive children. Furthermore, we have not
systematically studied or adjusted for factors such as salt intake,
physical activity and dietary habits, which would be pertinent for future
surveys. Findings of the present study suggest a need for larger
population based studies to accurately estimate the prevalence
hypertension among children in our country.
Contributors: AS, NG and SLK were involved in
concept and protocol design, review of literature, analysis and
preparation of manuscript. RB was involved in collection, analysis and
interpretation of data and finalization of the manuscript. NS was involved
in analysis, interpretation and finalization of the manuscript. AS serves
as guarantor of the study.
Funding: None.
Competing interests: None stated.
|
What This Study Adds?
• Prehypertension or hypertension was found in nearly 20% school
children in Shimla.
|
References
1. Shear CL, Burke GL, Freedman DS, Berenson GS. Value
of childhood blood pressure measurements and family history in predicting
future BP status: Results from 8 years of follow-up in the Bogalusa Heart
Study. Pediatrics 1986; 77: 862-869.
2. Tanne JH. Children should have blood pressure and
cholesterol checked by age of 5. Br Med J 2002; 325: 8.
3. Krishna P, Bajaj S, Thennarasu K, Desai N, Prasamma
KM. Regional differences in the reference blood pressure in young Indians.
Indian Pediatr 2007; 44: 921-923.
4. Gupta AK, Ahmad AJ. Normal blood pressures and the
evaluation of sustained blood pressure elevation in childhood. Indian
Pediatr 1990; 27: 33-42.
5. Mohan B, Kumar N, Aslam N, Rangbulla A, Kumbkarni S,
Sood NK, et al. Prevalence of sustained hypertension and obesity in
urban and rural school going children in Ludhiana. Indian Heart J 2004;
56: 310-314.
6. Anand NK, Tandon L. Prevalence of hypertension in
school going children. Indian Pediatr 1996; 33: 377-381.
7. Rao S, Kanade A, Kelkar R. Blood pressure among
overweight adolescents from urban school children in Pune, India. Eur J
Clin Nutr 2007; 61: 633-641.
8. Cole TJ, Bellizi MC, Flegal KM, Dietz WH.
Establishing a standard definition for child overweight and obesity
worldwide: international survey. Br Med J 2000; 320: 1240-1244.
9. National High Blood Pressure Education Program
Working Group on High Blood Pressure in Children and Adolescents. The
Fourth Report on the diagnosis, evaluation and treatment of high blood
pressure in children and adolescents. Pediatrics 2004; 114: 555-575.
10. Update on the 1987 Task Force Report on High Blood
Pressure in Children and Adolescents: a working group report from the
National High Blood Pressure Education Program. National High Blood
Pressure Education Program Working Group on Hypertension Control in
Children and Adolescents. Pediatrics 1996; 98: 649-658.
11. CDC Growth charts: United States, In: Ghai
OP, Gupta P, Paul VK. Ghai Essential Pediatrics, 6th ed. CBS Publishers:
New Delhi, 2004. p. 7-43.
12. Jafar TH, Islam M, Poulter N, Hatcher J, Schmid CH,
Levey AS, et al. Children in south Asia have higher body
mass–adjusted blood pressure levels than white children in the United
States: A comparative study. Circulation 2005; 111; 1291-1297.
13. Ostchega Y, Carroll M, Prineas RJ, McDowell MA,
Louis T, Tilert T. Trends of elevated blood pressure among children and
adolescents: data from the National Health and Nutrition Examination
Survey 1988-2006. Am J Hyperten 2009; 22: 59-67.
14. Rames LK, Clarke WR, Connor WE, Reiter MA, Lauer
RM. Normal blood pressure and evaluation of sustained blood pressure
elevation in childhood: the Muscatine study. Pediatrics 1978; 61: 245-251.
15. Sorof JM, Lai D, Turner J, Poffenbarger T, Portman
RJ. Overweight, ethnicity, and the prevalence of hypertension in school
aged children. Pediatrics 2004; 113: 475-482.
16. Muntner P, He J, Cutler JA, Wildman RP, Whelton PK.
Trends in blood pressure among children and adolescents. JAMA 2004; 291:
2107-2113.
17. He Q, Ding ZY, Fong DYT, Karlberg J. Blood pressure
is associated with body mass index in both normal and obese children.
Hypertension 2000; 36: 165-170.
|
|
|
 |
|
