STUDY ON RELATIONSHIP BETWEEN WAIST CIRCUMFERENCE AND BLOOD PRESSURE AMONG SCHOOL GOING ADOLESCENTS

STUDY ON RELATIONSHIP BETWEEN WAIST CIRCUMFERENCE AND BLOOD PRESSURE AMONG SCHOOL GOING ADOLESCENTS

DISSERTATION SUBMITTED FOR THE DEGREE OF M.D BRANCH VII

(PAEDIATRIC MEDICINE) APRIL 2017

THE TAMILNADU

D.R M.G.R MEDICAL UNIVERSITY

CHENNAI, TAMILNADU

CERTIFICATE

This is to certify that the dissertation entitled “STUDY ON RELATIONSHIP BETWEEN WAIST CIRCUMFERENCE AND BLOOD PRESSURE AMONG SCHOOL GOING ADOLESCENTS” is the bonafide work of Dr. KESAVAN.M.R in partial fulfilment of the university regulations of the Tamil Nadu Dr. M.G.R Medical University, Chennai, for M.D Degree Branch VII – PAEDIATRIC MEDICINE examination to be held in April 2017.

.

Dr. M.R. VAIRAMUTHURAJU M.D., Dean,

Madurai Medical College,

Government Rajaji Hospital,

Madurai.

CERTIFICATE

This is to certify that the dissertation entitled “STUDY ON RELATIONSHIP BETWEEN WAIST CIRCUMFERENCE AND BLOOD PRESSURE AMONG SCHOOL GOING ADOLESCENTS” is the bonafide work of Dr. KESAVAN M R in partial fulfilment of the university regulations of the Tamil Nadu Dr. M.G.R Medical University, Chennai, for M.D Degree Branch VII – PAEDIATRIC MEDICINE examination to be held in April 2017

DR. M.S. RAJARAJESWARAN MD DCH DR. K. MATHIARASAN MD DCH

Professor of Paediatrics, Professor & Director

Institute of Child Health & Institute of Child Health &

Research Centre, Research Centre,

Madurai Medical College Madurai Medical College

DECLARATION

I, DR.KESAVAN.M.R, solemnly declare that the dissertation titled “STUDY ON RELATIONSHIP BETWEEN WAIST CIRCUMFERENCE AND BLOOD PRESSURE AMONG SCHOOL GOING ADOLESCENTS” has been conducted by me at the Institute of Child Health and Research centre, Madurai under the guidance and supervision of my unit Chief PROF. DR.

M.S.RAJARAJESWARAN M.D., D.C.H.

This is submitted in part of fulfilment of the award of the degree of M.D (Paediatrics) for the April 2017 examination to be held under the Tamil Nadu Dr.M.G.R Medical University, Chennai. This has not been submitted previously by me for any Degree or Diploma from any other University.

Place: Madurai Date:

Dr.KESAVAN.M.R

ACKNOWLEDGEMENT

I sincerely thank Prof. Dr.M.R.Vairamuthuraju, the Dean, Government Rajaji Hospital and Madurai Medical College for permitting me to do this study.

I express my profound gratitude to Prof. Dr. K. Mathiarasan, Professor and Director, Institute of Child Health & Research Centre, Madurai, for his able supervision, encouragement, valuable suggestions and support for this study.

I am greatly indebted to my teacher, Prof. Dr.S.Balasankar and Prof .Dr.M.S.Rajarajeswaran who guided me throughout my study. I am also greatly thankful for his able supervision, critical review, constant encouragement and full support rendered in every aspect of this study

I express my sincere thanks to Prof. Dr. M. Nagendran, Prof. Dr. M.

Kulandaivel,, Prof. Dr. S. Shanmugasundaram, Prof. Dr. N. Muthukumaran , for their guidance and encouragement throughout the study.

I would like to express my sincere gratitude to former Chiefs Prof. Dr.

G.Mathevan, Prof.Dr.S.Sampath M.D, DCH, Prof DR.Chitra Ayappan M.D, DCH, FRCPCH, FIAS.

I wish to express my sincere thanks to my guide and assistant professors

Dr. P.Ramasubramaniam M.D, and Dr.P.Kannan M.D, for their invaluable guidance, support and suggestions at every stage of this study.

I also express my gratitude to all other assistant professors of our

Department and my fellow post graduates for their kind cooperation in carrying out this study.

I also thank the members of the Ethical Committee, Government, Rajaji Hospital and Madurai Medical College, Madurai for allowing me to do this study.

I express my sincere thanks to my better half Mrs.Nithya.R for her support throughout my study.

Last but not the least, I submit my heartfelt thanks to the children and their

parents for extending full co –operation to complete my study successfully.

ABBREVIATIONS HT : Hypertension

SHT : Systolic Hypertension BP : Blood Pressure

SBP : Systolic Blood Pressure DBP : Diastolic Blood Pressure WC : Waist Circumference WtHR : Waist to Height Ratio CVD : Cardiovascular Disease BMI : Body Mass Index

NHANES : National Health and Nutrition Examination Survey

STEPS : STEPwise Approach to Surveillance (WHO)

WHO : World Health Organization

ABSTRACT Background:

Hypertension is on the raise among school children. Overweight and obesity especially in childhood and adolescents play important role in development of insulin resistance, DM, Hypertension. Obesity indicators like BMI, Waist circumference, WtHR play important role in predicting children with high blood pressure.

Aim and Objective:

To study the relationship between Waist circumference and blood pressure among school going adolescents. And to examine the utility of waist circumference as an indicator of elevated BP compared to BMI.

Methodology:

1392 school going children were included. Their height, weight, Waist circumference and Blood pressure were recorded. BMI was calculated.

Results:

In this cross sectional study carried out on 1392 adolescents in Madurai the incidence of Pre Hypertension and Hypertension was 3.4% and 1.8%

respectively. 6% were overweight, 3% were obese. 6.6 % of the children had

increased waist circumference. Prediction of Prehypertension and Hypertension

among children was found to be statistically significant with Sensitivity= 90.41%,

specificity= 98.03%, ppv=71.74%, npv=99.46%. Prediction of children with high blood pressure by BMI was also found to be statistically significant with Sensitivity= 89.04%, specificity= 95%, ppv=49.62%, npv=99.37%

Conclusion:

Obesity indicators like Waist circumference, BMI because of its ease of measurement can be used as a screening tool to identify children with high blood pressure.

Key words: Waist circumference, BMI, Blood Pressure

TABLE OF CONTENTS

Sl.No. Chapters Page No.

1 Introduction 1

2 Review of literature 2

3 Aim & Objectives 47

4 Methodology 48

5 Results and Analysis 50

6 Discussion 83

7 Conclusion 85

8 Limitation 85

9 Bibliography 87

10

Annexure

 Proforma of the study

 Master chart

 Ethical clearance certificate

 Plagiarism

95

STUDY ON RELATIONSHIP BETWEEN WAIST CIRCUMFERENCE AND BLOOD PRESSURE AMONG SCHOOL GOING ADOLESCENTS

INTRODUCTION

“Hypertension i.e. elevated systolic and /or diastolic BP is now considered to be

on the raise among school going children in recent times.

In India it has been noted that children are on the verge of obesity associated elevated blood pressure.

It has been known that Blood pressure tracks over time; children with increased values are now at an elevated chance of acquiring Hypertension in older age group.”

“Blood pressure readings for children require trained doctors to identify and take out the appropriate values. Since this is difficult to be carried out in schools, utilization of anthropometric measures which are being carried at school physical examination is found to be beneficial and early identification of those young children and adolescents who are at the verge of having elevated blood pressure.

Usually, waist-to height ratio (WHtR), body mass index (BMI) and waist

circumference (WC) which are used as obesity indicators among adults

children

and adolescents can also be utilised as an indicator of High blood pressure.”

Waist Circumference is considered as a good predictor of central adipose tissue deposition and is noted to be a strong predictor of hypertension in Indian adolescents

WC is predictive of such adverse outcomes as abnormal lipid profile and insulin resistance and is a component of paediatric metabolic syndrome

The National Health and Nutrition Examination Survey (NHANES) has proposed the 90th percentile as the cut-off for identifying central adiposity.

REVIEW OF LITERATURE

Childhood hypertension is now emerging as a global health problem. Earlier it was thought that secondary hypertension alone was common among children and adolescents. But later it was found that incidence of primary hypertension is escalating.

Prevalence of primary hypertension among children is noted to be between 3-5%

and pre hypertension about 7-10% in various studies. This is because of increase in the prevalence of obesity, decreased physical activity among children and increased consumption of junk foods.

“Both central and generalized obesity are found to be linked with higher chances

of overall mortality and morbidity. The primary reason for obesity associated

mortality is CVD, for which abdominal obesity is an important precipitating factor.”

“In ancient times BMI has been chosen as an indicator for measuring the body size and structure, and for the diagnosis of nutritional status among children.

However, other methods that reflect abdominal adiposity like waist–hip ratio waist circumference, and waist to height ratio, have been considered to be superior to BMI in predicting the risk for CVD. This is due to the fact that increased visceral adipose tissue deposition is linked to a very wide range of metabolic abnormalities that includes impaired blood sugar levels, decreased insulin sensitivity and deranged lipid levels, which are now a risk for diabetes hypertension and CVD.”

“Based on an extensive review, Huxley et al. (2010) finally concluded that there

was solid evidence stating that measurement of general obesity (e.g. BMI) and

measures of abdominal adiposity (E.g. waist circumference, waist–hip ratio and

waist–height ratio) are linked to increased CVD related events. The authors also

noticed that the measurement of abdominal obesity is considered to be superior

to BMI as predictors of CVD risk, although they noticed that combination of BMI

with Waist circumference, waist to hip ratio etc. may improve their

discriminatory capability. For any given level of BMI, waist circumference or

waist–hip ratio, the absolute risk of diabetes or hypertension (risk factors for CVD incidence) is higher in some population than in Caucasian.”

Ethnic Differences: When studies done among children of Asian origin are considered, it is noticed that Asians (Indians) have elevated metabolic risk at lower waist circumference and waist–hip ratio than Europeans. This may be because of increased amount of body fat and abdominal adipose tissue.

Waist Circumference:

It is a very simple and easy way to identify and look for “abdominal obesity”

Advantages:



It is easy to measure



Inexpensive



Strong correlation with body fat when compared with other accurate methods.

Waist circumference can predict the morbidity of the disease

Methods for measuring waist circumference

1. Placement of the Tape:

“The WHO STEPS protocol is used for the measurement of waist circumference and it says that the measurement should be made at the approximate midpoint between the lower margin of the last palpable rib and the top of the iliac crest.

The United States (US) National Institutes of Health (NIH) protocol provided in the NIH Practical guide to obesity (NHLBI Obesity Education Initiative, 2000) and the protocol used in the US National Health and Nutrition Examination Survey (NHANES) III indicate that the waist circumference measurement should be made at the top of the iliac crest i.e. at the upper lateral border of right ilium.”

. 2. Tightness and type of tape:

“As per this protocol for measurement of waist circumference the tape should be snug tightly around the person, but not to the level of constriction. A stretch resistant tape should be used for this purpose that must be able to give a constant amount of tension of about 100 g. This can be achieved by the utilization of a special indicator type of buckle.”

3. Subject posture and other factors

“As per WHO STEPS protocol child must stand with their arms by their side

hanging, feet must be placed together so that the body weight can be distributed

evenly across.”

“The NHANES III protocol recommends that the subject be standing erect, with

the body weight evenly distributed.”

“This protocol recommends that measurement of the waist circumference to be done at the end of a normal expiration so as to ensure that the lungs are maintained at their FRC.”

“The person must be in a relaxed mood before the measurements are to be made.

They should take a take a few deep, natural breaths before measurements so as to reduce the inward pulling of the abdominal contents during measurements.”

“It has to be done two times provided the measurements are within 1 cm of each other, the average should be calculated. If the difference between the two measurements exceeds 1 cm, the two measurements should be repeated.”

Relationships between waist circumference and waist–hip ratio in predicting disease risk and Mortality:

“1. Measurement of central i.e. abdominal obesity is considered to be superior to BMI in predicting the ultimate risk for CVD, although combining BMI with these measurements has been found to increase their discriminative capacity.

• For any given level of BMI, waist circumference or waist–hip ratio, it has been

noticed that the absolute risk of diabetes or hypertension (risk factors for CVD

incidence) is considered to be higher than among Caucasian people.”

2. “Qiao & Nyamdorj (2010) stated that, in relation to Diabetic mellitus, all Anthropometric measures (BMI, waist circumference, waist–hip ratio and waist–

height ratio) similar in identifying the risk level. However, most of the data obtained from many cross‐sectional and case control studies states that waist circumference or waist–hip ratio are considered to be better than BMI in detecting the risk for Diabetic mellitus.”

3.”In the INTERHEART case–control study of myocardial infarction done over varied populations groups among 52 countries (Yusuf et al., 2005), BMI, waist circumference (WC) and waist–hip ratio were all strongly and linearly associated with risk of myocardial infarction ,stroke and hypertension. Relationships with BMI were attenuated by adjustment for waist–hip ratio, but relationships with waist circumference measurements were relatively unaffected by adjustment for BMI, indicating the independence of measures of abdominal obesity in predicting risk.”

Waist Circumference percentiles in Indian children

Due to wide variation in central adiposity based on age, gender and ethnicity

difference there has been variation in the cut-off used for waist circumference

among children .Waist Circumference percentile curves for Indian children age and sex wise was identified by Khadilkar et al

Age and sex specific Waist circumference has been identified in their study. And

their ROC has suggested 70

percentile as a risk for metabolic syndrome.

BODY MASS INDEX (BMI)

Body Mass Index (BMI) is used for defining childhood obesity. Overweight is defined as BMI greater than or equal to 85

percentile and less than 95th percentile compared with children belonging to same age and sex. For obesity definition the BMI must be greater than or equal to 95

percentile compared with the children of same age and sex. BMI is to be calculated by dividing the child’s weight in kilogram by the square of height in meters. For children BMI is age and sex specific. Body Mass Index is relatively a simple measure and a valuable tool..

BMI in children are affected by variances like age, sex, height hormonal factors, adiposity rebound phenomenon etc. Against this backdrop the International obesity task force (IOTF) has concluded that the definition of obesity in children should be consistent with adults, a reference representative of the world population. Asian children, particularly Indian children carry the tendency to have a higher percentage fat and more sensitive to metabolic consequences.

Indian Academy of Pediatrics has updated the BMI chart in coherence and with same method as the IOTF criteria being more appropriate for Indian children.

IAP BMI Charts:

Interpretation

Normal Range: 5

to 85

Percentile.

Overweight: > 85

to 95

Percentile. (23 Adult equivalent risk for overweight)

Obese: > 95

Percentile. (27 Adult equivalent risk for obesity)

IAP BMI CHART BOYS

IAP BMI CHART GIRLS

Waist to hip Ratio:

“WHR is now being increasingly used for measurement of abdominal obesity. It is calculated by measurement of the waist and then measuring the hip at the widest diameter of the buttock. Dividing the waist measurement by the hip measurement gives the waist to hip ratio.”

Advantages:

“Has a very good correlation with body fat when compare with measurements of

other specific methods.

Inexpensive

Waist-to-hip ratio can help in predicting disease risk”

Limitations:

“Error while measuring are noticed frequent because it requires minimum of 2

readings to be taken.

It is difficult to measure hip circumference when compared to measuring waist circumference.

More complex to interpret than waist circumference; reason being waist-to-hip

ratio can be altered by increased abdominal fat or decrease in lean muscle mass

in the hip.”

Two people with varied BMIs can have similar WtHR this is because turning two different measurements to ratio, leading to loss of information.

May be difficult to measure and less accurate and difficult to measure when BMI is >35.

HYPERTENSION

“To define hypertension among children and adolescents it should be always

based on the normative blood pressure data provided among healthy children.

Normal Blood Pressure is usually defined by Systolic Blood Pressure and Diastolic Blood Pressure that is less than the 90th percentile for sex, age, and height.”

“Hypertension is defined as the average SBP or DBP that is greater than or equal

to the 95th percentile for sex, age, and height taken on at least three different occasions.”

Definition of Hypertension as per “The JNC 7 Committee states that for

prehypertension definition the recommended Blood Pressure level must be more

than 120/80 mmHg and it also has recommended preventive health-related

strategies and certain lifestyle changes, for individuals having SBP levels that

exceed 120 mmHg.

Latest recommendation states that just like the elderly or

adults even for children with BP levels more than or equal to 120/80 mmHg, but

which is below the 95th percentile, can be taken as prehypertensives.”

White-coat hypertension:

“A clinical situation in which the child and or patient is reported to be having

Blood pressure levels greater than 95th percentile when it is detected in hospital setting while the patient’s average BP is found to be much lower than 90th percentile outside health care facility.”

Measurement of Blood Pressure in Children:

This is to be done among all children greater than or equal to three years of age during each and every hospital visit.

“The Blood Pressure tables given for children are actually based on the

auscultatory methods utilised for measurements, therefore the ideal method for measurement among children is by means of auscultation. To confirm hypertension, the BP in children is measured by using a standard clinical sphygmomanometer, by means of a stethoscope that has to be placed over the brachial artery pulse, proximal and medial to the cubital fossa, and below the bottom edge of the cuff (i.e., about 2 cm above the cubital fossa).When the bell of the stetescope is being used then it will easily pick up certain softer korotkoff sounds very easily.”

This is found to be of practical importance.

“Ideally BP should be measured after having ensured that the child has not taken

any provocating food items or medications that is known to aggravate Blood

pressure, and has to be at a position of comfort or ease for at least minimum of

five minutes, and seated with his back properly supported, feet on the floor and right arm supported, and the cubital fossa must be at the level of the heart.

It is generally considered to take measurements using the right arm than compared to using the left arm because in certain conditions like Coarctation of aorta there are probabilities of false low values which can be depicted in left arm.”

“For the correct measurement of Blood Pressure in children requires the use of a

cuff that should be appropriate to the size of the child’s upper right arm. The equipment necessary to measure BP in children, ages three through adolescence, includes child cuffs of different sizes and must also include a standard adult cuff, a large adult cuff, and a thigh cuff. The latter two cuffs may be needed for use in adolescents.”

“By convention, an appropriate cuff size is a cuff with an inflatable bladder width

that is at least 40 percent of the arm circumference at a point midway between the olecranon and the acromion.”

For such a cuff to be optimal for an arm, the cuff bladder length should cover 80–100 percent of the circumference of the arm.

Such a requirement demands that the bladder width to- length ratio be at least 1:2.”

Cuff bladder length (80 to 100% of arm circumference)

Cuff bladder width (about 40% of arm circumference SBP is determined by the onset of the “tapping” Korotkoff sounds (K1).

The fifth Korotkoff sound (K5), or the disappearance of Korotkoff sounds, is DBP. The standard device for BP“measurements has been the mercury manometer.

Because of its environmental toxicity, mercury has been increasingly removed from health care settings. Elevated BP must be confirmed on repeated visits before characterizing a child as having hypertension.”

“Blood Pressure monitoring in child younger than 3 years

■ Preterm babies, Birth weight less than 1500 grams, NICU admission

■ UTI, haematuria

■ Kidney disorders or anomalies

CHD

■ Positive Family history of renal pathology

■ Solid organ transplant

■ Cancer, BMT

■ Drugs

■ Systemic diseases

■ ICT”

“Ambulatory BP monitoring (ABPM): It is a process where a portable BP

device, which is used by the patient, records BP over a period of time which is about one day. It is utilised for detecting and or initiating treatment of hypertension among young kids.

By frequently measuring the Blood Pressure, ABPM helps in arriving at the mean BP during the day, night, and for the 24 hours period and also in the measurement of the various degrees where BP exceeds the upper limit of normal over a time frame (i.e., the BP load). ABPM is useful in evaluating white-coat hypertension, the risk for hypertensive target organ injury, any apparent drug resistance, and hypotensive symptoms with antihypertensive drugs. ABPM is also useful for evaluating patients for whom more information on BP patterns is needed, such as those with episodic hypertension, chronic kidney disease, diabetes, and autonomic dysfunction.

Conducting ABPM requires specific equipment and trained staff. Therefore,

ABPM in children and adolescents should be used by experts in the field of

paediatric hypertension who are experienced in its use and interpretation.”

ETIOLOGY AND PATHOPHYSIOLOGY OF HYPERTENSION IN CHILDREN

BP is defined as the product of peripheral vascular resistance (PVR) and cardiac output.

“An increase in either peripheral vascular resistance or the cardiac output leads to elevated Blood Pressure; if any one of these variables raises while the other falls, BP may not increase. When hypertension is because of any other disease process, it is commonly noted as secondary hypertension.”

“For primary it is defined when there is no identifiable cause that could be attributed to. Many factors, like hereditary, stress, diet, increased BMI, may be involved in the pathogenesis of developing primary hypertension.”

“Secondary hypertension is commonly seen in young infants and young children.

The younger the child, the higher the BP and the presence of symptoms related to hypertension, the more likely there will be an underlying secondary cause of hypertension. Many childhood diseases can be attributed to be responsible for chronic hypertension or intermittent hypertension .The most likely cause varies with age of presentation.”

“Chronic Hypertension causes

1. RENAL

 Chronic pyelonephritis

 CGN

 Hydro nephrosis

 Congenital renal anomalies

 Cancer of the kidney

 Injury to kidney

 Solitary renal cyst

 Post irradiation insult

 VUR nephropathy

 Segmental hypoplasia of the kidney

 Ureteral obstruction

 Transplant rejection

 SLE”

“VASCULAR

 Coarctation of abdominal aorta or thoracic aorta

 Renal artery lesions (stenosis, fibromuscular dysplasia, thrombosis , aneurysm)

 AV shunts

 NF

 Umbilical artery catheterization (UAC) with thrombus formation

 Renal vein thrombosis

 Certain Vasculitis syndromes

 Williams-Beuren syndrome

 Moya Moya disease

 Giant cell arteritis”

“ENDOCRINE

 Hyperthyroidism

 Hyperparathyroidism

 CAH

 Cushing syndrome

 Primary Aldosteronism

 Apparent mineralcorticoid excess

 Liddle syndrome

 Geller syndrome”

“CENTRAL NERVOUS SYSTEM

 Tumors of CNS

 Intracranial bleed

 Traumatic brain insult

 Quadriparesis”

“Causes for Transient or Intermittent Hypertension in Children

1. RENAL

 APSGN

 HSP

 HUS

 ATN

 After renal transplantation (immediately and during episodes of rejection)

 Post transfusion azotaemia

 Volume overload state

 Post-surgical complication of genitourinary tract

 Acute Pyelonephritis

 Injury to the kidney

 Malignant infiltrates of the kidney

 Crohns disease”

2. “MEDICATIONS AND TOXINS

 Cocaine

 OCP

 Sympathomimetic agents

 Amphetamines

 Phencyclidine”

 “Lead, mercury, cadmium, thallium

 Antihypertensive withdrawal (clonidine, methyldopa, propranolol)

 Vitamin D intoxication

 Corticosteroids and adrenocorticotropic hormone

 Cyclosporine or sirolimus treatment post transplantation

 Licorice ingestion””

3. “CENTRAL AND AUTONOMIC NERVOUS SYSTEM

 Raised ICT

 GBS

 Acute Intermittent Porphyria

 Polio

 Burns injury”

 Spinal cord injury (autonomic storm)

 “Familial dysautonomia

 SJS

 Posterior fossa lesions

 Encephalitis”

4. “MISCELLANEOUS

 Preeclampsia

 Fractures of long bones

 Hypercalcemia

 Following Coarctation of aorta repair

 WBC transfusion

 ECMO

 Obstruction of the airways”

Hypertension in preterm babies due to catheterization of umbilical artery or renal vein thrombosis.

In early childhood period kidney disease, Endocrine disease, Coarctation of aorta is identified.

“Children and adolescents associated with primary (essential) hypertension are

commonly overweight, often have a strong family history of hypertension, and

usually have BP values at or slightly above the 95

percentile for age. Primary

hypertension is the most common form of hypertension in adults, and it is

recognized more often in adolescents than in young children .The cause of

primary hypertension is likely to be multifactorial; such as obesity, genetic alterations in calcium and sodium transport, vascular smooth muscle reactivity, the renin–angiotensin aldosterone system, sympathetic nervous system over activity, and insulin resistance have been implicated in this disorder. Elevated levels of uric acid might play a crucial role in the pathophysiology of primary hypertension and proof-of-concept studies have confirmed that lowering of uric acid levels results in lower BP in overweight youth with hypertension or

Prehypertension. Some children and adolescents demonstrate salt sensitive Hypertension, a factor that is ameliorated with weight loss and sodium restriction.”

Evaluation of essential Hypertension and its risk factors:

“During childhood primary hypertension is associated with mild and / or Stage 1

hypertension and usually has a positive family history of HT or Coronary vascular

disease. Obesity is usually associated among children with essential

hypertension. Various studies all over the globe have noticed that in those

children with elevated Body mass index it has been noted that the incidence of

hypertension is on the raise. Approximately 30% of children who are obese have

high BP.”

“This strong association of elevated BP with obesity and the marked increase in

the prevalence of childhood obesity

indicate that both hypertension and prehypertension are becoming a significant health issue in the young. Overweight children frequently have some degree of insulin resistance — a prediabetes condition. Overweight and high BP are also part of the insulin-resistance or the metabolic syndrome, a condition associated with multiple metabolic risk factors for CVD as well as for type 2 diabetes.”

“The clustering of other CVD risk factors that are included in the insulin

resistance syndrome (high triglycerides, low high-density lipoprotein cholesterol [HDL-C], truncal obesity, and hyperinsulinemia) is found significantly higher among children with high BP than in children with normal BP.”

“Earlier hypertension in childhood was considered as a simple independent risk

factor for CVD, but its link to the other risk factors in the insulin-resistance syndrome indicates that a broader approach may be appropriate in affected children .So a detailed history, physical examination, and laboratory evaluation of hypertensive children and adolescents is required. Risk factors, in addition to high BP and overweight, include low plasma HDL-Elevated plasma triglyceride, and abnormal glucose tolerance.”

“Fasting plasma insulin concentration is generally elevated, but an elevated

insulin concentration may be reflective only of obesity and is not diagnostic of

the insulin-resistance syndrome. To identify other cardiovascular risk factors, a

fasting lipid panel and fasting glucose level should be obtained in children who are overweight and have BP between the 90th and 94th percentile and in all children with BP greater than the 95th percentile. If there is a strong family history of type 2 diabetes, a hemoglobin A1c or glucose tolerance test may also be considered. These metabolic risk factors should be repeated periodically to detect changes in the level of cardiovascular risk over time.”

“In children with primary hypertension, the presence of any comorbidity that is

associated with hypertension carries the potential risk to increase the risk for CVD and can have an adverse effect on health outcome. Considering these associated risk factors and appropriate evaluation in those children in whom the hypertension is verified are important in planning and implementation therapies that could decrease the comorbid risk as well as controlling Blood Pressure.”

Evaluation for Secondary Hypertension

It is more common among children than adults.

“Very young children, children with Stage 2 hypertension, and children or

adolescents with clinical signs that suggest the presence of systemic conditions

associated with hypertension should be evaluated more extensively as compared

to those with Stage 1 hypertension”

“A thorough history and physical examination are the first steps in the evaluation

of any child with persistently elevated BP. Elicited information should aim to identify not only signs and symptoms due to high BP but also clinical findings that might uncover an underlying systemic disorder. Thus, it is important

to seek signs and symptoms suggesting renal disease (gross haematuria, edema, fatigue), heart disease (chest pain, exertional dyspnoea, palpitations), and diseases of other organ systems (e.g., endocrinologic, rheumatologic).”

“Questions regarding trauma, UTI, sleep disorders must be elucidated. Family

history of HT, DM, obesity, disorders of sleep, kidney pathology, Cerebrovascular accident, MI must be elicited. Drug history is important as many medications are available easily over the counter. Many drugs are notorious for increasing blood pressure levels.”

“While examining the child it is imperative to first measure the anthropometric

indices like waist circumference, weight, height etc. Strong association of obesity

with hypertension has now made that measurement of BMI is very essential and

its value calculated using the IAP BMI charts. Poor growth may indicate an

underlying chronic illness. When hypertension is confirmed, BP should be

measured in both arms and in a leg. Normally, BP is 10–20 mmHg higher in the

legs than the arms. If the leg BP is lower than the arm BP, or if femoral pulses

are weak or absent, coarctation of the aorta may be present.”

“Target-Organ Abnormalities in Childhood Hypertension:”

“Strong link or correlation of Hypertension with elevated chances of Stroke , MI

,and other cardiovascular risk has been noted among adolescents and adults ,

and management of high BP results in marked reduction in the risk of cardiovascular events.”

“Children and adolescents with marked elevation BP are also at increased risk of

adverse outcomes, including hypertensive encephalopathy, convulsions, cerebrovascular accidents and congestive heart failure.”

“When High Blood pressure is associated with CKD it has been noted that the

end organ damage is present even at low blood pressures .The time limit and the elevation of Blood pressure causing target organ damage in children is not known.”

“Non-invasive techniques like utilization of ultrasound which can demonstrate

structural and functional changes in the vasculature related to BP.Recent clinical studies using these techniques demonstrate that childhood levels of BP are associated with carotid intimal-medial thickness

and large artery compliance

(41)

in young adults.”

“LVH is the most prominent clinical evidence of target-organ damage caused by

hypertension in children and adolescents.”

Abnormalities of “the retinal vasculature have been reported in adults with Hypertension”

CLINICAL RECOMMENDAT I O N

“Echocardiography is now being recommended as a primary tool for evaluating

patients for target organ abnormalities by assessing the presence or absence of LVH.”

“Left ventricular mass is being determined from standard echocardiographic

Measurements of the left ventricular end-diastolic dimension (LVED), the intraventricular septal thickness (IVS), and the thickness of the left ventricular posterior wall (LVPW) and can be calculated as: LV Mass (g) = 0.80 [1.04

(IVS + LVED + LVPW) 3 – (LVED) 3] + 0.6 (with echocardiographic measurements in centimetres).”

Left ventricular mass index is calculated to standardize measurements of left

ventricular mass

“Children and adolescents with established hypertension should have an

echocardiogram to determine if LVH is present. A conservative cut point that

determines the presence of LVH is 51 g/m2. This cut off point is above the

99th percentile for children and adolescents and is associated with increased

morbidity in adults with hypertension.”

Condition such as overweight, obesity, central adiposity has a pathological effect over the heart. It has to be kept in mind while utilizing left ventricular mass index.

Ascertainment of left ventricular mass index is very helpful in clinical decision making.

“Left ventricular hypertrophy is now considered as an early indication of starting

antihypertensive medication. For those children who are having Left ventricular hypertrophy it is mandatory that the left ventricular mass index is determined on a regular basis.”

“Currently additional testing for other target organ abnormalities (such as

determining carotid intimal-medial thickness and evaluating urine for microalbuminuria) is not recommended for routine clinical use.”

Nonpharmacological treatment of hypertension in children and adolescents:

“Weight reduction in overweight or obese individuals

Increased daily intake of fresh vegetables, fruits, and lowered fat dairy (the

Dietary Approaches to Stop Hypertension Study [DASH] eating plan)

Dietary reduction of sodium, increasing the physical activity and reduction in the consumption of alcohol. Smoking cessation has significant cardiovascular benefits.”

“Because of the strong correlation between weight and BP, excessive weight gain

is more likely to be associated with elevated Blood Pressure over time. So, maintaining normal weight gain in childhood would lead to decreased chance of hypertension in later life. Weight loss in overweight adolescents is associated with an estimated reduction in BP. Weight control not only reduces Blood Pressure, it also decreases BP sensitivity to salt and decreases other cardiovascular risk factors, such as dyslipidaemia and insulin resistance. In studies that achieve a reduction in BMI of around 10 percent, short-term reduction in Blood Pressure were in the range of 8–12 mmHg. Although difficult, weight loss, if successful, is highly effective. Identifying a complication of overweight, such as hypertension, can be a helpful motivator for patients and families to make certain lifestyle changes. Weight control can easily make pharmacological treatment unnecessary but should not delay drug therapy use especially when indicated.”

“Education and certain behavioural changes can be implemented in those patients

who are willing to attain weight loss or prevent weight gain. Children must spend

adequate time in playing outdoor games and in reduction of sedentary activities

like computer games playing, viewing television etc. to be reduced to less than

120 minutes per day

The family and patient should identify those physical activities that the child enjoys and must engage in them regularly, and self- monitor the time spent in physical activities (30–60 minutes per day) should be achieved.”

“Dietary changes include portion-size control, decrease in consumption of sugar-

containing beverages and energy-dense snacks, elevated consumption of fresh fruits and vegetables, and regular meals including a healthy breakfast.”

“Sodium reduction in children and adolescents has been associated with small reductions in BP, in the range of 1–3 mmHg.”

“Sodium intake must be restricted to about 1.2 g/day for 4- to 8-year-old children and 1.5 g/day for older children.”

“Regular physical activity is associated with many cardiovascular benefits. A

recent meta-analysis that combined 12 randomized trials, for a total of 1,266 children and adolescents, concluded that physical activity leads to a small, but not statistically significant, decrease in BP.” (48)

“However, both regular physical activity and decreasing sedentary activity—such

as watching television and playing video or electronic games—are important components of paediatric obesity treatment and prevention.”

“Regular aerobic physical activity (30–60 minutes of moderate physical activity

on most days) and limitation of sedentary activities to less than 2 hours per day

are recommended for the prevention of obesity, hypertension, and other cardiovascular risk factors.”

Pharmacologic Therapy of Childhood Hypertension

“The short and long term consequences of untreated hypertension among children

is not known much. Effect of anti-hypertensive drugs on the child’s growth is not known. Initiation of drug therapy in children should be started meticulously after giving undue consideration.”

“Indications for Antihypertensive Drug Therapy in Children

■ Symptomatic hypertension

■ Conditions causing Secondary hypertension

■ Hypertensive target-organ damage

■ Diabetes (types 1 and 2)

■ Unresponsive to drug therapy”

“Specific types of antihypertensive medications must be utilized selectively

among certain class of hypertensive children in regard to the predisposing

pathological or clinical situation. Examples such as the utilising Angiotensin

converting enzyme inhibitor or Angiotensin Receptor Blockers in children with Diabetic mellitus, micro albuminuria or renal pathology or utilising beta- adrenergic blockers or calcium channel blockers (CCB) in hypertensive children with certain types of migraine headaches is essential.”

“All antihypertensive medications should be delivered in the same pattern. The

child should be initiated on the lowest possible recommended dose. Gradually the strength can be titrated upwards until the desired effects are achieved i.e. blood pressure control.”

“A drug from another class must be initiated when adequate control of blood

pressure is not achieved with the highest possible dosage of the drug or when side effects of the drug is being reported. Drugs having complementary mechanism of action can be given in combination such as diuretic with Angiotensin Converting Enzyme inhibitor, or a vasodilator with a diuretic or beta-adrenergic blocker.”

For those children associated with uncomplicated primary hypertension and no hypertensive target organ damage, the goal BP should be less than the 95th percentile for sex, age, and height, whereas for those children with chronic

Renal disease, diabetes, or hypertensive target organ damage, the target BP should be less than 90th percentile for sex, age, and height.

It is imperative to keep a check on the levels of sodium, potassium etc., look for

side effects of drugs, any end organ damage, drug resistant while giving the anti-

hypertensive drugs. Advice and education must be provided for the children on the basis of non-pharmacological treatment also. Step down therapy can also be tried in some children based on their clinical response. This approach widely helps in gradual reduction of the drugs after an extended course of good Pressure control is achieved, with eventual goal of completely discontinuing the drug therapy. Children with uncomplicated primary hypertension, especially those overweight or obese children who successfully lose weight, are now being considered as the best candidates for this step-down approach.

Such patients require ongoing BP monitoring even after the cessation of drug therapy, as well as continued nonpharmacological treatment, because there are chances that hypertension may sometimes recur.

Severe, symptomatic hypertension with BP well above the 99th percentile occurs in some children, usually those with underlying renal disease, and it requires immediate treatment.

“Hypertensive emergencies in children are commonly associated with signs of

hypertensive encephalopathy causing convulsions. These must be treated by an

intravenous antihypertensive drug which produces a controlled reduction in BP,

with the sole objective of reducing by 25 percent over the first 8 hours of arrival

in the emergency department followed by slowly reducing the pressure over the

next 1 to 2 days.”

“Hypertensive urgencies: Is another clinical scenario that causes less severe

clinical features like that of severe headache, nausea, projectile vomiting.

Management is by utilisation of antihypertensive drugs parenteral or by mouth

based on the child’s clinical features on presentation.”

“Stepped-care approach to antihypertensive therapy in children and

adolescents”

AIM AND OBJECTIVE

1. To study on the relationship between waist circumference and blood pressure among school going adolescents.

2. To examine the utility of waist circumference as an indicator of elevated blood pressure when compared to BMI

Study design: Cross sectional observational study.

Period of study: 5 months (April 2016-August 2016)

Study subject: School children aged 11 - 17 years, numbering 1392 (50.5% boys

& 49.5% girls) formed the study group.

Inclusion criteria:

Healthy school going children aged 11 to 17 years in Madurai Exclusion criteria:

Children already diagnosed to have secondary hypertension.

Children having any acute illness.

Present history suggestive of cardiovascular, chronic respiratory or any other systemic illness

Children on chronic drugs like steroids

Ethical clearance: Was obtained from the Institutional ethical committee.

Approvals was also obtained from the Principal of participating schools

Method of collection of data:

The details of the students were collected in a pre-structured proforma.

Anthropometric indices of the children like height, weight and waist circumference were measured. Blood pressure was measured for all children after five minutes of rest in seated position with the right arm supported at the level of the heart.

For children whose Blood Pressure were above 90th centile reading was repeated twice at 5-10 minutes interval in the same visit and average Blood Pressure was recorded. Blood Pressure consistently between 90-95th centile were considered to be pre-hypertensive.

For children whose BP was above the 95th percentile, Blood Pressure recordings were repeated at weekly intervals twice and Blood Pressure reading that was found to be consistently above 95th percentile were considered as hypertensive.

Height for each student was measured, Non-elastic measuring tape, fastened to a vertical wall was used.

For weight measurement, an electronic weighing scale was used to measure weight.

From these values “Body Mass Index was calculated using this formula

BMI = Weight (kg)/Height (m)

.”

Waist circumference measurement were performed in accordance with methodology used in the NHANES.

Waist Circumference for the children were measured with the child standing erect by using a stretch-resistant tape. The tape was applied horizontally just above the upper lateral border of the right ilium. Each measurement were made at the end of a normal expiration and recorded to the nearest 0.1 cm.

STATISTICAL ANALYSIS

For statistical analysis the data was entered in MS Excel and analysed using SPSS v20. Qualitative data were summarised as frequencies and percentages.

Quantitative data were checked for normality. Normally distributed data were

summarised using mean and standard deviation. Median and interquartile range

was used for summarizing non normally distributed data. Association between

qualitative variables were tested using chi square tests. Difference in distribution

of quantitative variables across the 2 groups were tested using using independent

t test and Mann Whitney U test using normal and non- normally distributed

variables respectively. Difference in distribution of quantitative variables across

more than two groups was tested using analysis of variance. Statistical

significance was interpreted using an arbitrary cut-off of p= 0.05.

RESULTS AND ANALYSIS Study Group elements

In this study a total of 1392 children were screened out of which 50.5% (n=703) were boys and 49.5% (n=689) were girls

Tables: Profile of study participants GENDER DISTRIBUTION

GENDER NUMBER PERCENTAGE

MALE 703 50.5

FEMALE 689 49.5

TOTAL 1392 100

50.5%

49.5%

Profile study of participants

Male Female

Table: Anthropometry of the study participants

Anthropometry Male Female Total

Height 153.9±12.36 151.34±10 152.65±11.32

Weight 41.86±12.13 42.08±8.96 41.97±10.67

Waist

circumference

65.84±9.35 66.5±8.65 66.17±9.01

BMI 17.31±3.21 18.11±2.67 17.71±2.98

In this study the anthropometric measurements of the study population were measured. The mean height for male children (153.9 cm) was found to be higher than that of females where it was found to be 151.34 cm.

The mean BMI was found to be higher among girls (18.11) than among boys where it was found to be 17.31.

The mean Waist circumference was also found to be higher among girls in this

study group compared to boys.

TABLE: Nutritional status of study population using BMI

BMI Category Frequency Percentage

Normal 1261 90.6

Overweight 91 6.5

Obese 40 2.9

Total 1392 100

CHART: Nutritional status of study population using BMI

NORMAL 91%

OVERWEIGHT 6%

OBESE

3%

BMI CATEGORY

NORMAL OVERWEIGHT OBESE

In the present study it was noted that out of the total 1392 children who were screened it was noted that the overall percentage of overweight children was found to be 6.5 % (n = 91) and the percentage of obese children in this study was found to be 2.9% (n = 40)

INCIDENCE OF OVERWEIGHT AND OBESITY

In this study it was noted that the incidence of obesity was found to be higher in

older age group. With obesity of 5.3% @ 17 years age , 3.5 % @ 14 years and

3.4 % at 15 years of age respectively.

Table: Age wise distribution of BMI

AGE Measure Normal Overweight Obese

11 N 176 17 8

% 87.6% 8.5% 4.0%

12 N 189 11 2

% 93.6% 5.4% 1.0%

13 N 188 13 1

% 93.1% 6.4% 0.5%

14 N 151 15 6

% 87.8% 8.7% 3.5%

15 N 187 11 7

% 91.2% 5.4% 3.4%

16 N 186 13 5

% 91.2% 6.4% 2.5%

17 N 184 11 11

% 89.3% 5.3% 5.3%

Total N 1261 91 40

% 90.6% 6.5% 2.9%

Figure: Age wise distribution of BMI

87.60%

93.60% 93.10%

87.80%

91.20% 91.20%

89.30%

8.50%

5.40% 6.40% 8.70%

5.40% 6.40%

5.30%

4.00%

1.00% 0.50% 3.50% 3.40% 2.50%

5.30%

0.00%

10.00%

20.00%

30.00%

40.00%

50.00%

60.00%

70.00%

80.00%

90.00%

100.00%

11 12 13 14 15 16 17

Normal Overweight Obese

Figure: Sex wise distribution of BMI in the study participants- Component bar graph

In this study it was found that more percentage of children were in obese category in males when compared to females. In males 3.6% were found to be obese, while among females only 2.2% were found to be in obese category. However in both groups percentage of overweight was found to be equal - 6.5% each.

89.9 91.3

6.5 6.5

3.6 2.2

M A L E F E M A L E

PERCENTAGE

Normal Overweight Obese

Mean and SD for BMI in each age group

AGE IN

YEARS

FREQUENCY MEAN STANDARD

DEVIATION

11 201 16.79 2.71

12 202 16.38 2.43

13 202 17.62 2.33

14 172 17.83 3.41

15 205 17.94 2.76

16 204 18.33 2.82

17 206 19.04 3.46

In this study it was noted that the mean BMI of study participants progressively

increased during their adolescent age. From mean BMI of 16.79 at 11 years to

19.04 at 17 years of age. The mean BMI was highest at 17 years of age (19.04)

followed by 18.33 at 16 years of age , 17.94 at 15 years of age.

Table: Age wise distribution of WC in Study population AGE Measure <70th

percentile

70-90th percentile

>90th percentile

11 N 184 12 5

% 91.5% 6.0% 2.5%

12 N 190 11 1

% 94.1% 5.4% 0.5%

13 N 191 10 1

% 94.6% 5.0% 0.5%

14 N 159 9 4

% 92.4% 5.2% 2.3%

15 N 193 5 7

% 94.1% 2.4% 3.4%

16 N 191 8 5

% 93.6% 3.9% 2.5%

17 N 192 7 7

% 93.4% 4.5% 2.1%

Total N 1300 62 30

% 93.4% 4.5% 2.1%

Waist circumference was measured among the study population. In this study it was noted that 6.6% of children had increased waist circumference.

6.6 % of children at 17 years of age had increased waist circumference

(70th percentile).6.4% of children at 16 years had elevated waist circumference

Figure: Sex wise distribution of WC in the study participants- Component bar graph

In this study it was noted that percentage of children who had elevated waist circumference was found to be 6.7 % in males which was slightly higher than females where it was found to be 6.5 %.

93.3 93.5

4.7 4.2

2 2.3

0 10 20 30 40 50 60 70 80 90 100

Male Female

Percentage

<70th percentile 70-90th percentile >90th percentile

Mean and Standard Deviation of waist circumference in study population

Age WAIST CIRCUMFERENCE VALUE

N Mean Std. Deviation

11 201 63.27 8.44

12 202 63.62 8.42

13 202 67.90 8.37

14 172 68.20 9.91

15 205 65.45 8.47

16 204 66.68 9.01

17 206 68.32 9.14

In this study the mean Waist circumference was found to be highest at 17 years

of age being 68.32 cm. Then mean waist circumference at 14 years of age was

found to be 68.2. The least mean waist circumference was noted at 11 years –

63.27 cm.

Figure: Box- Whiskers plot showing distribution of Waist circumference in study population- sex wise

This picture depicts sex wise distribution of waist circumference in the study

population.

AGE WISE DISTRIBUTION OF BLOOD PRESSIURE

AGE Normal Prehypertension Hypertension

11 189 9 3

94.0% 4.5% 1.5%

12 195 5 2

96.5% 2.5% 1.0%

13 192 9 1

95.0% 4.5% 0.5%

14 164 5 3

95.3% 2.9% 1.7%

15 191 9 5

93.2% 4.4% 2.4%

16 194 7 3

95.1% 3.4% 1.5%

17 194 4 8

94.2% 1.9% 3.9%

Total 1319 48 25

94.8% 3.4% 1.8%

In this study the incidence of pre hypertension was found to be 3.4% (n=48) and that of hypertension was found to be 1.8% (n= 25).

Incidence of hypertension was found to be higher in older age group when it was compared to younger age group.

Highest incidence of hypertension was found at 17 years of age – 3.9%

followed by 2.4% at 14 years of age.

Least incidence of hypertension was found at 13 years of age – 0.5 %.

The incidence of pre hypertension was detected at younger age group – 4.5% at 11 and 13 years of age group.

It was found out that the incidence of hypertension was found to be higher in

later adolescent age group when compared to early adolescent period.

AGE WISE DISTRIBUTION OF BLOOD PRESSIURE IN STUDY POPULATION

94.00%

96.50%

95.00% 95.30%

93.20%

95.10% 94.20%

4.50% 2.50%

4.50%

2.90% 4.40% 3.40% 1.90%

1.50% 1.00% 0.50% 1.70% 2.40% 1.50%

3.90%

0.00%

10.00%

20.00%

30.00%

40.00%

50.00%

60.00%

70.00%

80.00%

90.00%

100.00%

11 12 13 14 15 16 17

Normal Pre Hypertension Hypertension

BP Percentile No of Children Percentage

Normal < 90% 1319 94.8

90-95 PRE HT

48 3.4

>95 HT

25 1.8

TOTAL 1392 100

Percentage of Children 0

10 20 30 40 50 60 70 80 90 100

< 90 90-95 (PRE HT) >95 (HT) 94.8

3.4 1.8

BLOOD PRESSURE DISTRIBUTION

Percentage of Children

Out of 1391 children 1319 (94.8%) had Normal BP of less than 90 th centile, 48(3.4%) with BP between 91-95th centile (PRE HYPERTENSION) and 25 (1.8%) students with BP more than 95th centile (HYPERTENSION).

Figure; Distribution of BP among normal, overweight and obese

individuals

In this study it was found that among patients with normal BMI the incidence of Pre Hyper tension and hypertension was found to be 0.63%.

Among those with overweight (BMI 85-95%), pre hypertension was found in

30.77 % of children and hypertension among 7.69 % of children. Among those

children who were overweight Pre hypertension was found in 30% of children

and Hypertension noted in 45% of the subjects.

Table: Association between Systolic BP and BMI among study participants BMI Normal Prehypertension Hypertension Chi square, p

value

Normal 1254(99.4) 7(0.6) 0 805.96,<0.001

Overweight 56(61.5) 28(30.8) 7(7.7)

Obese 10(25) 12(30) 18(45)

In this study it was found that Systolic hypertension was found in 45 % of obese children, 7.7% with overweight children and none in children with normal BMI.

It was found statistically significant with p value <0.001

99.4

61.5

25

0.6

30.8 30

0

7.7

45

0 20 40 60 80 100 120

NORMAL OVERWEIGHT OBESE

ASSOCIATION OF SYSTOLIC BP AMONG CATEGORIES OF BMI

NORMAL PRE HYPER TENSION HYPERTENSION

Table: Association between Diastolic BP among categories of BMI

BMI Normal Prehypertension Hypertension Chi square, p value

Normal 1259(99.8) 2(0.2) 0 589.8,<0.0001

Overweight 66(72.5) 22(24.2) 2(3.3)

Obese 17(42.5) 14(35) 9(22.5)

In this study it was found that incidence of Hypertension was found to be 22.5 % among obese children, 3.30% with overweight and none with normal BMI. It was found to be statistically significant with p value <0.0001.

99.80%

72.50%

42.50%

0.20%

24.20%

35%

0% 3.30%

22.50%

0.00%

20.00%

40.00%

60.00%

80.00%

100.00%

120.00%

NORMAL OVERWEIGHT OBESE

ASSOCIATION OF DIASTOLIC BP AMONG CATEGORIES OF BMI

NORMAL BP PRE HYPERTENSION HYPERTENSION