Prevalence of Hypertension and Prehypertension in Iranian Children

AUTHORS

Farshid Kompani ORCID 1 , Azar Nickavar 2 , * , Mohammad Reza Khalilian 3 , Sara Rahafard 4 , Behdokht Abuali 5 , Seyyed Mohammad Mahdi Hosseiny 6

1 Pediatric Nephrology Division, Neonatal and Children's Health Research Center, Golestan University of Medical Sciences, Gorgan, Iran

2 Department of Pediatric Nephrology, Iran University of Medical Sciences, Tehran, Iran

3 Department of Pediatrics, School of Medicine, Shahid Beheshti University of Medical Sciences, Tehran, Iran

4 Neonatal and Children's Health Research Center, Golestan University of Medical Sciences, Gorgan, Iran

5 Ahvaz Jundishapur University of Medical Sciences, Ahvaz, Iran

6 Pediatric Neurology Fellowship, Tehran University of Medical Sciences, Tehran, Iran

How to Cite: Kompani F, Nickavar A, Khalilian M R, Rahafard S, Abuali B, et al. Prevalence of Hypertension and Prehypertension in Iranian Children. Nephro-Urol Mon.In Press(In Press):e114828. doi: 10.5812/numonthly.114828.

ARTICLE INFORMATION

Nephro-Urology Monthly: In Press (In Press); e114828
Published Online: August 16, 2021
Article Type: Research Article
Received: March 27, 2021
Accepted: June 13, 2021
Uncorrected Proof scheduled for 13 (4)
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Abstract

Background: Hypertension (HTN) is a significant public health problem worldwide. Early diagnosis of HTN and its related risk factors has been considered as one of the main requirements of general healthcare in children.

Objectives: This study aimed to examine the nomograms of normal systolic and diastolic blood pressure (BP) and the prevalence of asymptomatic HTN and pre-HTN in a population of school-aged children.

Methods: Systolic and diastolic BP, height, and weight were measured in 5811 healthy school-aged children (2904 males and 2907 females) during healthcare visits. HTN was defined as systolic or diastolic BP ≥ 95th percentile for age, gender, and height of the screened population on ≥ 3 occasions. Pre-HTN was considered as systolic or diastolic BP between 90 - 95 percentile.

Results: HTN and pre-HTN were detected in 8.4% and 7.8% of the children, respectively. The prevalence of HTN was 8.6% among the males and 8.2% among the females. Systolic HTN and pre-HTN were detected in 5.8 and 6.4% of the cases compared to diastolic HTN and pre-HTN observed in 5.9 and 6.1% of the participants, respectively. In addition, HTN was detected in 27.9% of children with obesity.

Conclusions: According to the high incidence of asymptomatic HTN and pre-HTN in asymptomatic children, it is recommended to perform routine BP measurement during medical care visits of all healthy school children and to prevent and treat obesity in childhood.

1. Background

The prevalence of pediatric hypertension (HTN) has been increasing throughout the world. In total, about 1 - 10% of children and adolescents suffer from HTN, and pre-HTN has been reported in 2 - 16% of children (1-4). HTN has also become increasingly recognized in 0.2 - 3% of newborn infants, particularly those requiring intensive care (5).

Primary HTN is highly prevalent in older children and adolescents. It is usually mild and asymptomatic, with potential cardiovascular and renal complications in untreated long-term patients (1, 4).

Increased body weight has been recognized as one of the potential risk factors of incipient and future HTN. The incidence of elevated blood pressure (BP) is over 15% in overweight and obese children. The increased consumption of a high calorie diet, lifestyle modification, and lack of physical activity are the major risk factors of increasing body weight and HTN (6).

2. Objectives

Limited studies have been conducted to identify the trend of increased blood pressure (BP) in children. Since early diagnosis and management of HTN might prevent further complications, this study was performed to identify the prevalence of HTN and pre-HTN in apparently healthy school-aged children.

3. Methods

This cross-sectional study was conducted on 5811 school children (7 - 11 years) admitted to the healthcare offices for routine clinical visits and referred to the nephrology clinics. The Local Ethics Committee of Gorgan University approved the study, and informed consent was obtained from the patients' legal guardians.

3.1. Inclusion Criteria

Asymptomatic healthy school-aged children with normal physical conditions without associated disorders were included in the study.

3.2. Exclusion Criteria

Children with a history of physical, mental, cardiac, renal, endocrine, nervous, and psychologic disorders, in addition to those on any medical treatments, were excluded from the study.

A single trained observer measured height, weight, and BP in all the children. Height for age standards was determined using the CDC 2000 growth charts and classified based on age and gender as short (≤ 25th percentile), average (25 - 75 percentile), and tall (≥ 75th percentile) stature.

Body mass index (BMI) was calculated by weight (kg)/height (m2) and classified as underweight (BMI< 5th percentile), normal (BMI: 5 - 85 percentile), overweight (BMI: 85 - 95 percentile), and obese (BMI > 95th percentile) (7). BP was determined after 3 - 5 minutes of rest in the sitting position, using the standard mercury sphygmomanometer, with an appropriate cuff covering two-thirds of the right arm. BP measurements was repeated within 2 weeks of the initial high BP value.

Systolic BP was determined by the onset of the first Korotkoff-1 sound, and diastolic BP was measured with the disappearance of Korotkoff-5. According to the Fourth Report on BP in Children and Adolescents (2004), normal BP is defined as the mean systolic and diastolic BP < 90th percentile for age, gender, and height on at least three occasions. Values between 90 - 95 percentile or > 120/80 mmHg in adolescents were defined as pre-HTN, and HTN was considered as BP ≥ 95th percentile on ≥ 3 different occasions (1, 7).

3.3. Statistical Analysis

The data were analyzed using IBM SPSS Statistics for Windows version 22.0. Continuous variables were expressed as mean ± standard deviation, and categorical variables were expressed as percentages. A P < 0.05 was considered statistically significant.

4. Results

A total of 5811 children (2904 males and 2907 females) aged between 7 - 11 years were enrolled in the study. Each age group consisted of about 20% of the cases. Systolic and diastolic BP based on weight and height in both genders are shown in Tables 1 - 4.

Table 1. BP Levels for Girls by Age and Height Percentile
Age (y)/BP percentileSBP, mm HgDBP, mm Hg
Height Percentile
5th10th25th50th75th90th95th5th10th25th50th75th90tht95th
7
50th9092959710010210551545658616365
90th969810010210410610856586163656769
95th989910110310510710859616365666870
99th9910110310510710911161636567697172
8
50th9192959810210611052535659636770
90th95969910210510911255565962667074
95th96979910210611011357586163677074
99th989910210510811211662636567697275
9
50th94959710110510710955565862666970
90th96989910510911211458596166707274
95th979910110611111411658606267727476
99th10010210410911311611861636570747779
10
50th969710010310610911157586165677173
90th9910110310710911211460616468717476
95th10010110410811011411561636569727577
99th10510610811111311511765666972747779
11
50th979910210611111411659616468727576
90th10010210510911411711863646771757879
95th10210410711011411711964666872767980
99th10510610811211611811967687073777981
Table 2. BP Levels for Boys by Age and Height Percentile
Age (y)/BP PercentileSBP, mm HgDBP, mm Hg
Percentile of Height
5th10th25th50th75th90th95th5th10th25th50th75th90th95th
7
50th899092969910210552535458606365
90th94959610010310610856575962656770
95th97989910210410710957596063666871
99th10010110210510610811061626366687073
8
50th9193969910310711052545760636770
90th959710010310711111456586164677174
95th979910210510811211557596265697376
99th9910110410610911211559616467707477
9
50th93949710210610911154565963677072
90th959710010511011311557596266717476
95th969810110611111411658606368727577
99th10010210510911411611862646771767981
10
50th959610110410711011156576265687172
90th989910410711011311559616569717476
95th10010110510911111411661626670737577
99th10110310811211511812062646872757980
11
50th9710010310711111411659616468727577
90th10110310611011411711963656871757880
95th10310510811111511812065677073767980
99th10610911111511912112468707376798284
Table 3. BP Levels for Girls by Age and Weight Percentile
Age (y)/BP PercentileSBP, mm HgDBP, mm Hg
Percentile of Weight
5th10th25th50th75th90th95th5th10th25th50th75th90th95th
7
50th9293959710010210553545658616365
90th9910010110310510710959606163666870
95th10110210210410610710961626365676971
99th10310410510610710811065666768707273
8
50th9294969910210510753555760636668
90th9810010110410610911058606264676971
95th10010210310510811011161626466687072
99th10310510610811011311464656768707273
9
50th95969710110410811056575863666972
90th9910010110610911311560616367707376
95th10110210310711011411662626468727578
99th10310410510911311611864656670737679
10
50th98999810310610911259605964677173
90th10110210210711011311562636368717577
95th10310410410811111411664656570737678
99th10610710711111411611867686872757779
11
50th10010110210610911311561626467707376
90th10410510711011411812067676972757880
95th10710811011211611912169707174767981
99th11211211311511712012175757677798081
Table 4. BP Levels for Boys by Age and Weight Percentile
Age (y)/BP PercentileSBP, mm HgDBP, mm Hg
Percentile of Weight
5th10th25th50th75th90th95th5th10th25th50th75th90th95th
7
50th899193969810110452545558606365
90th96989910110410610858606163656870
95th9810010110310510710959616264676971
99th10010210310510710911162646567697174
8
50th9494969910110610955555759626670
90th10110110310410611011261616365677174
95th10210210410610711011363636566687174
99th10510510710810911111365656768707376
9
50th95969810110611011157576063677172
90th999910210611111511760616467717677
95th10010110410811211711962626569737879
99th10510510811111411811966676972767981
10
50th979810010310711011259606264687173
90th10210210510711111511763646669727678
95th10310410610911211611864656770737778
99th10410510811211712212566677073788385
11
50th10010110310611011411661626467717576
90th10510610811111411711968687072757879
95th10810911011311511811971727374767879
99th11111111311511712012174747577788081

Mean systolic and diastolic BP were 101.41 mmHg (57.5 - 125 mmHg) and 62.51 mmHg (44.5 - 85.0 mmHg) in all the cases, respectively. Mean systolic/diastolic BP was 101.5/62.7 mmHg in the males and 101.2/62.3 mmHg in the females. Overall, mean systolic and diastolic BP increased with age, weight, height, and BMI in both genders.

The majority of the patients had normal BP (83.8%), followed by pre-HTN (7.8%) and HTN (8.4%). Most of the patients had normal systolic BP (87.8%), followed by systolic pre-HTN (6.4%) and systolic HTN (5.8%). In addition, the patients mostly had normal diastolic BP (88%), followed by diastolic pre-HTN (6.1%) and diastolic HTN (5.9%).

The majority of the males (82.9%) and the females (84.7%) had normal BP. However, 8.6% of the males and 8.2% of the females had HTN, while 8.5% of the males and 7.1% of the females had pre-HTN. The distribution of systolic and diastolic BP in both genders is shown in Table 5.

Table 5. Frequency of Normal BP, Systolic and Diastolic HTN, and pre-HTN in Both Genders (%)
GenderNormal BPTotal HTNTotal Pre-HTNSHTNDHTNS Pre-HTND Pre-HTN
Males82.98.68.55.8676.4
Females84.78.27.15.95.75.75.8

Abbreviations: SHTN, systolic HTN; DHTN, diastolic HTN; SPre-HTN, systolic pre-HTN; Dpre-HTN, diastolic pre-HTN.

Of the children, 22.5% were short, 55% were average, and 22.5% were tall. The prevalence of HTN was 5.5%, 7.9%, and 10.1% in short, average, and tall patients, respectively.

The mean BMI was 16.65 kg/m2 (10.24 - 31.74). Of the children, 5.2% were underweight, 80.1% were normal, 10% were overweight, and 4.7% were obese. Further, the prevalence of HTN was 6.6, 6.3, 16.7, and 27.9% in underweight, normal, overweight, and obese children, respectively. Of children with pre-HTN, about 4.7% were underweight, 7.3% were normal, 11.7% were overweight, and 11.2% were obese (Table 6, Figures 1 - 4).

Table 6. Frequency of Normal BP, pre-HTN, and HTN Based on Weight in Both Genders (%)
WeightNormal BPPre-HTNHTN
MaleFemaleMaleFemaleMaleFemale
Underweight89.787.85.53.84.88.3
Normal 85.787.186.66.36.3
Overweight70.17312.810.617.116.3
Obese5665.511.211.332.823.2
Figure 1. Nomogram of diastolic BP by BMI in girls
Figure 2. Nomogram of diastolic BP by BMI in boys
Figure 3. Nomogram of systolic BP by BMI in girls
Figure 4. Nomogram of systolic BP by BMI in boys

5. Discussion

The development of adult HTN may start early in life (8). Persistent HTN during infancy and early childhood is the primary cause of cardiovascular events, chronic kidney disease, and stroke in adulthood. Accordingly, early detection of HTN and its risk factors in different communities seems necessary to prevent future HTN-related complications and morbidity (4, 5).

The present study’s findings indicated that the mean systolic and diastolic BP increased in the children with increasing age, height, weight, and BMI in both genders, showing the effect of age, height, weight, and BMI on BP measurement in both genders. Moreover, HTN and pre-HTN were documented in 8.4 and 7.8% of our children, reflecting the need for more attention to this health problem. Similarly, HTN and pre-HTN were detected in 5.9 and 12.3% of children in Sharma et al.'s study, which is considered an alarming condition (8).

The prevalence of pre-HTN and HTN was 31.4 and 2.1% in Koebnick et al.'s study, indicating an average 7% of young children with HTN (9).

In a cohort of 199513 children, including 3 - 5 (24.3%), 6 - 11 (34.5%), and 12 - 17 (41.2%) years old children, about 12.7 and 5.4% had pre-HTN and HTN, respectively, with a positive correlation with age and BMI (10).

About 8.4 and 7.5% of our children with HTN and pre-HTN were males and females, respectively. In total, 5.8 and 6.3% of our children had systolic or diastolic HTN and pre-HTN, respectively.

In another study, 13.6% of boys and 5.7% of girls aged 8 - 17 years were classified as pre-hypertensive, in addition to 2.6% of boys and 3.4% of girls with established HTN (8). However, the prevalence of HTN and pre-HTN was nearly equal in both genders in our study.

Similarly, systolic and diastolic HTN and pre-HTN had nearly equal frequency in our population. Systolic and diastolic HTN were detected in 0.8 and 0.4% of patients in the update of Taskforce Report on BP, with no significant difference between girls and boys regarding the prevalence of systolic HTN (2.7%), but with a higher number of girls with diastolic HTN. In addition, systolic BP was significantly higher in boys than girls, whereas DBP was significantly higher in girls than boys (11).

The prevalence of obesity has been increased secondary to dietary habits, increased salt intake, and decreased physical activity. A strong correlation has been recognized between increased body weight and HTN, and obesity has been considered a significant risk factor of HTN, especially systolic BP (11 - 30%) (6, 12, 13). Therefore, prevention and treatment of obesity might decrease the incidence of HTN.

About 27.9 and 11.2% of our obese children had HTN and pre-HTN, respectively, composing a relatively high number of children with increased BP and emphasizing increased body weight as a major predictor of future HTN.

The prevalence of HTN and pre-HTN was 22.0 and 13.3% in Ramos et al.'s study, with a higher incidence in males (25.4 vs. 18.8%). They documented HTN in 14.7, 24.2, and 42.3% of normal, overweight, and obese female children and 20.4, 35.5, and 41.3% of their male counterparts, respectively (14).

Many children with normal BMI had high BP values in Rahman et al.'s study (6). However, HTN was more severe among obese children with BMI >30. Of them, 37.5% had pre-HTN, and 12.5% had HTN. In their report, age, female gender, and BMI > 25 were independent risk factors of HTN and pre-HTN.

The overall prevalence of systolic or diastolic HTN was 4.2, 5.4, and 7.7% in Kelishadi et al.'s study (15), without a significant difference between genders, similar to our study. In addition, both systolic and diastolic HTN occurred more commonly in overweight and tall children.

5.1. Conclusion

Due to the high incidence of HTN, regular monitoring of BP is recommended in asymptomatic healthy-appearing children to prevent its further risks in adulthood. Further studies with larger populations are suggested to estimate the true incidence of HTN in different communities.

Footnotes

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