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|Year : 2019
: 12 | Issue : 2 | Page
|Prevalence of hypertension and prehypertension in schoolchildren from Central India
Ashish Patel1, Anil Bharani1, Meenakshi Sharma2, Anuradha Bhagwat3, Neepa Ganguli3, Dharampal Singh Chouhan4
1 Department of Medicine, MGM Medical College, Indore, Madhya Pradesh, India
2 Scientist ‘F’, Division of Noncommunicable Diseases, Indian Council of Medical Research, New Delhi, India
3 JVMM Project on Community Control of Rheumatic Fever/Rheumatic Heart Disease, Rheumatic Fever/Rheumatic Heart Disease Registry, Indore, India
4 Department of Community Medicine, R D Gardi Medical College, Ujjain, Madhya Pradesh, India
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|Date of Web Publication||30-Apr-2019|
| Abstract|| |
Background: Epidemiological transition with increasing burden of cardiovascular risk factors is evident not only in adults but also in children. The data on the prevalence of prehypertension and hypertension in children show large regional differences in India and such data are not available from Central India. We, therefore, conducted a large cross-sectional study in Indore to determine the distribution of blood pressure (BP) and the prevalence of hypertension and prehypertension among schoolchildren.
Methods: A total of 11,312 children (5305 girls, 6007 boys) aged 5–15 years, drawn from 80 government and private schools in equal proportion, were evaluated. Anthropometric measurements were obtained and BPs were measured using The Fourth Report on The Diagnosis, Evaluation, and Treatment of High Blood Pressure in Children and Adolescents as reference standard. BP ≥90th to <95th percentile for given percentile of height was considered as prehypertension, whereas any BP ≥95th percentile was defined as hypertension. Multiple linear regression analysis was used to find out the determinants of hypertension in these children.
Results: Prehypertension was detected in 6.9% and 6.5% and hypertension was found in 6.8% and 7.0% of boys and girls, respectively. Height and weight were found to be a significant predictor of systolic and diastolic BP among both boys and girls.
Conclusions: Our results show a high prevalence of prehypertension and hypertension in Indore schoolchildren with age and height being significant determinants. This highlights the need for routine BP measurements in children by pediatricians when they treat them for intercurrent illnesses or vaccinate them. It should also be mandatory as a part of school health checkup programs to detect childhood hypertension for further counseling and therapy.
Keywords: Blood pressure, pediatric hypertension, school health checkup
|How to cite this article:|
Patel A, Bharani A, Sharma M, Bhagwat A, Ganguli N, Chouhan DS. Prevalence of hypertension and prehypertension in schoolchildren from Central India. Ann Pediatr Card 2019;12:90-6
|How to cite this URL:|
Patel A, Bharani A, Sharma M, Bhagwat A, Ganguli N, Chouhan DS. Prevalence of hypertension and prehypertension in schoolchildren from Central India. Ann Pediatr Card [serial online] 2019 [cited 2019 Aug 21];12:90-6. Available from: http://www.annalspc.com/text.asp?2019/12/2/90/257389
| Introduction|| |
It has been shown that even a slight elevation of blood pressure (BP) in childhood is likely to elevate the risk of hypertension by several folds in adult population.,,, Epidemiological transition with increasing burden of cardiovascular risk factors such as obesity and hypertension is already evident not only in adult population but also in pediatric population in developing countries including India.,,,,,, The survey data show large variation in the prevalence of prehypertension and hypertension among the children from various part of India.,, Further, large studies on the prevalence of pediatric hypertension from Central India are lacking.
The present study was conducted as part of the Indian Council of Medical Research (ICMR) Jai Vigyan Mission mode project on “Community Control of Rheumatic Fever/Rheumatic Heart Disease” (2007–2014). Our primary aim was to know about the distribution of BP in schoolchildren aged 5–15 years and secondarily to find out the prevalence of prehypertension and hypertension among them. The Fourth Report on The Diagnosis, Evaluation, and Treatment of High Blood Pressure in Children and Adolescents was used as reference standard.
| Methods|| |
The sample size was calculated using the formula from the WHO STEPwise approach to chronic disease surveillance (N = Z2 × P [1-P]/e2), where N = sample size, Z = level of confidence, P = baseline level of the selected indicator, and e = margin of error. P was estimated at 0.50 (recommended by the STEPS survey guidelines when the estimated baseline is unknown), Z = 1.96 (at 95% confidence interval), and e = 0.05; thus, the estimated sample size was n = 1.962 × 0.5 (1–0.5)/0.052 = 384. This basic sample size was adjusted for design effect for age–sex estimates, 5–15 years' age range (1-year intervals), and the required sample size was, therefore, n = 384 × 2× 11 = 8448.
We studied a total of 11,312 children (5305 girls, 6007 boys) from 80 schools located in 43 out of total 69 municipal wards of Indore. Schools were selected to represent students attending government schools and private schools in equal proportions. The protocol was approved by the Institutional Ethics and Scientific Committee.
Blood pressure measurement
The mercury BP instrument used in our study was new leak proof and their accuracy was checked with standard mercury manometer (Baumanometer, W. A. BAUM Co., Inc., New York, USA) kept for calibration purposes.
The children were evaluated by a team consisting of two specially trained pediatricians, two research assistants, and a social worker who visited the school at least a week before the examination date. The preexamination visit was intended to familiarize with the teachers and students and to discuss and schedule the plan of examination.
All children were clinically examined in a comfortable position in a noise-free room during morning hours. Weight was measured using a calibrated scale and height using a stadiometer. BP measurement was carried out using mercury sphygmomanometer, following standard guidelines in sitting position. At least 5 min of rest in sitting position was provided before taking BP. Children were asked to sit on appropriate sized chairs, allowing for comfortable sitting with back supported, legs uncrossed and touching the ground, and arm supported during measurements. Observers and children were instructed to keep silence. The right arm was selected for BP measurement for consistency. Appropriate BP cuff was selected covering at least 40% of arm circumference with midline of cuff positioned over the arm following palpation of the brachial artery in the antecubital fossa. BP was measured in each child three times at a minimum interval of at least 5 min in between successive measurements on the same day. The onset of the first Korotkoff sound was taken as systolic BP (SBP) and end of Korotkoff sounds as diastolic BP. In circumstances where Korotkoff sounds were heard till 0 mmHg, the BP measurement was repeated with less pressure on the head of the stethoscope. In the event of persistence of very low fifth Korotkoff sounds, fourth Korotkoff sounds (muffling of the sounds) were recorded as the diastolic BP.,,
First readings of both SBP and diastolic BP were discarded to lessen the effect of anxiety on BP. A mean of the second and third values, for both SBP and diastolic BP, was computed and taken as BP of the child and used for further analysis. Body mass index (BMI) was calculated based on height and weight data for every child in the entire cohort [Table 1]. Data from The Fourth Report on The Diagnosis, Evaluation, and Treatment of High Blood Pressure in Children and Adolescents were considered as reference value for defining prehypertension and hypertension.
|Table 1: Distribution of anthropometric variables according to age and gender|
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BP ≥90th to <95th percentile was considered as prehypertension, and BP ≥95th percentile was considered as systemic hypertension. Further, hypertension was classified as Stage I (≥95th to ≤99th percentile plus 5 mmHg) and Stage II (>99th percentile plus 5 mmHg). We added 5 mm to observed ≥95th and ≥99th-percentile values to define Stage I and Stage II hypertension more clearly since the difference between the 95th and 99th percentiles is only 5–10 mmHg which is not large enough. Further, children were considered to have prehypertension if they were found to have SBP >120 mmHg and/or diastolic BP >80 mmHg, even if this value is <90th percentile of BP for each year of age group.
Multiple linear regression with stepwise forward elimination was used to assess the determinants of SBP and diastolic BP in the reference sample. Separate analyses were performed for sex, SBP, and diastolic BP. The results suggested that age and height were the principle determinants of SBP and height was the principle determinants of diastolic BP in our study sample. To evaluate BP levels at specific height percentiles for 1-year age groups, we first converted height percentiles to the z-score scale.
We then regressed BP on height for each 1 year for male and female groups. Separate analyses were performed for SBP and diastolic BP thus:
- SBP(age)=α1+ β1 (z height) + e1 (Equation 1)
- Diastolic BP(age)= α2+ β2 (z height) + e2 (Equation 2).
As the third step, we estimated the 95th and 90th percentiles for BP at specific height percentiles for each 1-year sex-pooled group. For instance, the 95th percentile of SBP for a child with height corresponding to the 90th percentile for the age group was estimated thus:
95th percentile of SBP (for age-specific 90th percentile of height) = α1+ β1 (1.28) +1.645 σ
where σ2 was estimated from the residual mean square from the regression model represented by Equation 1.
The corresponding 90th percentile of SBP for the child would be:
90th percentile of SBP (for age-specific 90th percentile of height) = α1+ β1 (1.28) +1.28 σ.
Similarly, percentile of diastolic BP was calculated using the regression model in Equation (2). All statistical analyses were performed using the SPSS 23 version (IBM Corp, USA) and Microsoft Excel (Microsoft Corp, USA).
| Results|| |
Age- and gender-specific distributions of anthropometric variables (weight, height, and BMI) in the study group are shown in [Table 1]. The age-specific BP distribution for boys and girls based on height percentile is shown in [Table 2] and [Table 3]. Cutoff values of height percentiles can be found in supplementary appendix [Supplementary Table 1 [Additional file 1]].
Data from The Fourth Report on The Diagnosis, Evaluation, and Treatment of High Blood Pressure in Children and Adolescents were considered as reference value for defining target BP, prehypertension, and hypertension. Prehypertension was detected in 6.9% and 6.5% of boys and girls, respectively, whereas hypertension was found in 6.8% (Stage I: 6.7%; Stage II: 0.1%) of boys and 7.0% (Stage I: 6.6%; Stage II: 0.3%) of girls [Table 4].
On regression analysis, age and height were the principle determinants of SBP and height was the principle determinants of diastolic BP in our study sample. Age- and sex-specific regression coefficients are presented in [Table 5].
| Discussion|| |
Primary hypertension in children was once considered a rarity and has emerged as an important public health problem world over. The prevalence of hypertension in children is high in India compared to developed countries like the USA where the prevalence of elevated BP was found to be 2.7%–3.7% in different population-based surveys. Similarly, the prevalence of childhood hypertension has varied between different populations within India [Table 6].,,,,, We have shown the distribution of normal BP in a large cohort of children between ages of 5 and 15 years and the prevalence of prehypertension and hypertension among them from Indore district of Madhya Pradesh situated in Central India. Prehypertension was detected in 6.9% and 6.5% of boys and girls, respectively, whereas hypertension was found in 6.8% of boys and 7.0% of girls. With this prevalence, one out of every ten children would require some intervention to control hypertension, to reduce the risk associated with elevated BPs during childhood., Chadha et al., in a sample of 10,215 schoolchildren from New Delhi, reported a much higher prevalence of hypertension (11.9% for boys and 11.4% for girls) which is not duplicated in other studies from Amritsar, Assam, Shimla, Surat, or by us at Indore.,,,, Using similar cutoff criteria of hypertension, Borah et al. from Assam reported hypertension in 7.6% of schoolchildren with a higher prevalence among girls, similar to our findings. Sharma et al. from Shimla reported a 5.9% prevalence of hypertension and 12.3% prevalence of prehypertension in school-going children aged 11–17 years. However, for defining stages of hypertension, they did not add 5 mmHg to the 95th and 99th percentile values as adopted in The Fourth Report on The Diagnosis, Evaluation, and Treatment of High Blood Pressure in Children and Adolescents.
Differences in the prevalence of hypertension among these studies could partly be attributed to selection of different cutoff points for defining hypertension, age difference, differences in the study design, the number of visits made for measurement of BP, and method of averaging BP taken between different visits. For example, we have discarded the first BP readings to lessen the effect of anxiety and taken the average of the second and third BP readings in consideration, whereas Borah et al. have used a mean of three measurements of BP.
We classified BP as normal, prehypertension, or hypertension based on a single BP reading on a planned school visit. Multiple studies have shown that repeated measurements on different occasions lead to a reduction in proportion of hypertensive patients., However, multiple readings of BP taken on the same day were also considered appropriate in a series of epidemiological surveys.
Children born to hypertensive parents are known to have a higher prevalence of hypertension. Further subclinical endothelial dysfunction has been reported in normotensive children of hypertensive parents. There is a high prevalence of hypertension in India affecting one-fourth of adult population. We have, however, not obtained a family history in our cohort and, therefore, do not know if parental hypertension in these children contributed to a higher prevalence of prehypertension and hypertension found in our study. Our study cohort had equal representation from relatively richer and economically deprived children; thus, any possible effect of socioeconomic status of the parents on BP is unlikely.,,, We have not performed detailed anthropometric measurements besides height, weight, and BMI and thus do not have information on the prevalence of central obesity in our study population that could have a bearing on observed BP. We have not evaluated the salt intake and other dietary habits and physical activities in our cohort. This could be considered in design of future studies specifically for the assessment of BP in children.
Despite these limitations, to conclude, there is a high prevalence of prehypertension and hypertension in our cohort. Thus, children should have BP recorded during school health checkups as a routine and further routine BP measurements should invariably be done when children come in medical contact for concurrent illnesses and for vaccination. Those who show elevated BPs should be counseled along with their parents and should be periodically followed by pediatricians and family practitioners for further therapy.
Financial support and sponsorship
This study was financially supported by ICMR, New Delhi, India.
Conflicts of interest
There are no conflicts of interest.
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Dr. Anil Bharani
119, Ravindra Nagar, Indore - 452 001, Madhya Pradesh
Source of Support: None, Conflict of Interest: None
[Table 1], [Table 2], [Table 3], [Table 4], [Table 5], [Table 6]