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Saudi Journal of Kidney Diseases and Transplantation
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Table of Contents   
ORIGINAL ARTICLE  
Year : 2020  |  Volume : 31  |  Issue : 6  |  Page : 1281-1293
Blood pressure standards for pre-school children in Saudi Arabia


1 Department of Pediatrics, College of Medicine, King Saud University, King Saud University Medical City, Riyadh, Kingdom of Saudi Arabia
2 Department of Biostatistics, Prince Naif Health Research Center, King Saud University Medical City, Riyadh, Kingdom of Saudi Arabia
3 King Saud Medical City, Ministry of Health, Riyadh, Kingdom of Saudi Arabia
4 Al Yamamah Hospital, Ministry of Health, Riyadh, Kingdom of Saudi Arabia
5 Pediatric Department, Al Habib Medical Group, Riyadh, Kingdom of Saudi Arabia

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Date of Web Publication29-Jan-2021
 

   Abstract 


The prevalence of hypertension (HTN) in children is increasing. Early detection of HTN in childhood may prevent the occurrence of complications in adult age. Blood pressure (BP) varies between populations according to ethnic and environmental factors. Based on these variations, reference norms developed for one particular population may not be applicable to others. Thus, this study aimed to provide age-, gender-, and height-related BP reference standards using oscillometric techniques for pre-school children in Saudi Arabia. A sub-sample of preschool children aged from 2 to 6 years was selected by multi-stage probability sampling of Saudi population. The samples represented Saudi children from the whole country. Data were collected through a house-to-house survey of all selected households in all 13 regions in the country. Oscillometric devices were used to measure the BP. Data were analyzed to study the distribution pattern of systolic (SBP) and diastolic BP (DBP) and to develop reference values based on age, gender, and height. The values for each age and height percentile were compared with the recent (2017) values of the North American children. A total of 2553 Saudi Arabian children (1299 boys and 1254 girls) aged 2–6 years with complete data on age, gender, height, SBP, and DBP were considered for analysis. Values for SBP and DBP were significantly higher in Saudi children than in the North American children. This study adds evidence to the BP variations between populations with influences such as genetic and environmental factors. The need of every population to define its normal BP standards is essential to avoid unnecessary investigations and anxiety in patients and their parents.

How to cite this article:
Al Salloum AA, El Mouzan MI, Al Sharqawi AH, Al Omar AA, Alqurashi MM, Al Herbish AS. Blood pressure standards for pre-school children in Saudi Arabia. Saudi J Kidney Dis Transpl 2020;31:1281-93

How to cite this URL:
Al Salloum AA, El Mouzan MI, Al Sharqawi AH, Al Omar AA, Alqurashi MM, Al Herbish AS. Blood pressure standards for pre-school children in Saudi Arabia. Saudi J Kidney Dis Transpl [serial online] 2020 [cited 2021 Oct 18];31:1281-93. Available from: https://www.sjkdt.org/text.asp?2020/31/6/1281/308337



   Introduction Top


The prevalence of hypertension (HTN) in children is increasing and is estimated to be ~3.5%.[1] HTN in children is often asymptomatic. Childhood HTN may lead to adult HTN.[2],[3] Early detection of hypertension can prevent cardiovascular disease, which is the main cause of mortality globally.[4] Therefore, evaluation of blood pressure (BP) has become a priority in health policies worldwide.[5]

Detection of high BP in children is difficult. References of systolic BP (SBP) and diastolic BP (DBP) depend on many parameters, such as age, gender, height, and weight.[6] Recently, the annual BP measurement for children ≥3 years was recommended.[1] Oscillometric BP devices are easier to use and may be more accurate for smaller children.[1] Age alone is inadequate to predict BP in children. Maturation represented by height is a better determinant of BP, independent of age.[7],[8]

BP varies between populations according to ethnic and environmental factors.[9] Thus, references of BP norms for a population may not be applicable to others.[5],[7],[10],[11],[12],[13],[14],[15],[16] We have previously investigated the BP standards for Saudi children based on age and sex alone.[17] In this study, we aimed to provide age, gender, and height-related BP reference standards using oscillometric techniques for pre-school-age children in Saudi Arabia.


   Methods Top


This study was part of the Health Profile of the Saudi Arabian Children and Adolescents project, which was a house-to-house survey of 14000 randomly selected households from all provinces in Saudi Arabia, including urban and rural areas. The present study was conducted in a subsample, which was selected randomly from the original main sample. Workshop training of field teams was conducted in each of the 13 provinces of the country. Training included practical demonstrations to members of the field teams on how to use and maintain the BP measurement devices.

Each team consisted of one physician and one to two female nurses. Clinical examination was performed to determine eligibility for measurements. Only healthy children and adolescents as determined by interview, clinical examinations, and anthropometric measurements were eligible for BP measurement. The exact birth date was considered to be particularly important and acceptable only when it was completely recorded from an official document. The exact date of measurement was also noted. Both dates were essential for the determination of the exact age at the time of measurements.

Electronic devices using oscillometric techniques were used in the study. The devices fulfilled the American Association for the Advancement of Medical Instrumentation (AAMI) and were graded A for both SBP and DBP under the British Hypertension Society (BHS) protocol, as recommended by the European Society of Hypertension.[18] All the devices were new and purchased especially for the study (Accutorr Plus, Datascope Corp, NJ, United States). The cuff was appropriate to the size of the upper arm according to the standard technique recommended by the working group report from the National High Blood Pressure Education Program.[19],[20] The right arm was used consistently, similar to other studies. Two readings, at the end of the interview and at the end of the physical examination, were performed for each subject with an interval of 5 min and in the presence of both parents. For children younger than two years, readings were taken in the supine position, and for children older than two years, in the sitting position. The lower BP level of the two readings was recorded for the final analysis.

Precautions were taken to ensure reliability and accuracy of measurements. In addition to the use of equipment known for having a high accuracy, intra-and inter-observer reliabilities were tested by selecting 1% of the children to be re-measured by the same or different observer. Multiple frequency analysis was used to detect any missing data, inconsistencies, and other types of questionable errors. All questionable data were double-checked. The details of the design and methodology of this study have been described in a previous study.[17]

All values were related to age, sex, and height of the children. The normal and abnormal BP values were categorized according to the new definitions of BP categories and stages by the New Guidelines of The American Academy of Pediatrics 2017[1] for children aged 1–13 years, which are as follows: normal BP, <90th percentile; elevated BP, ≥90th percentile to <95th percentile or 120/80 mm Hg to <95th percentile (whichever is lower); and stage 1 HTN: ≥95th percentile to <95th percentile +12 mm Hg or 130/80 to 139/89 mm Hg (whichever is lower); and stage 2 HTN, ≥95th percentile +12 mm Hg or ≥140/90 mm Hg (whichever is lower).


   Statistical Analysis Top


Data were analyzed using IBM SPSS Statistics for Windows version 22.0 (IBM Corp., Armonk, NY, USA). Continuous variables were expressed as mean ± standard deviation, and categorical variables as percentages. The t-test was used for continuous variables. A P <0.05 was considered statistically significant.

We used the methodology of the Fourth Report of the Task Force on Blood Pressure Control in Children.[21] First, we calculated the age-specific height percentiles of the reference sample, and then converted height percentiles to the Z-score scale.

The 50th, 90th, 95th, and 99th percentiles of SBP and DBP-specific height percentiles were estimated using a regression equation for mixed-effects linear regression models: μ = α+, where α, ß1...ß4... γ1... γ4 are regression Coefficients. For SBP and DBP, the 90th percentile is 1.28 σ, the 95th percentile is 1.645 σ, and the 99th percentile is 2.326 σ over the mean, where σ2 was estimated from the residual mean square from the regression model.


   Results Top


A total of 2553 Saudi Arabian children (1299 boys and 1254 girls) aged 2–6 years with complete data on age, gender, height, and SBP and DBP readings were considered for the analysis. The characteristics of children are given in [Table 1]. Our results show that the mean body weight, height, SBP, and DBP increase with increasing age. Most of the children were 2 years of age (n = 346, boys) and (n = 304, girls), whereas the remaining children was aged 3 and 4 years (n = 197,227) for boys and girls, respectively.
Table 1: Mean (standard deviation) height, weight, systolic, and diastolic blood pressure by age and gender.

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In boys, the mean BP values increased with age, and SBP at the ages of 2 and 6 years was equal to 94.16 mm Hg and 102.12 mm Hg, respectively. For DBP, it was 57.80 and 63.04 mm Hg for ages 2 and 6, respectively. In girls, the same trend was also observed; SBP increased from 92.95 mm Hg at the age 2 to 102.74 mm Hg at age 6, and DBP increased from 56.02 (age 2) to 63.51 mm Hg (age 6).

For mean SBP and DBP values, there was no statistically significant difference between boys and girls, except for DBP at age 2.

The percentile BP levels by age and height percentiles for boys and girls are reported in [Table 2] and [Table 3]. It is clear that SBP and DBP increased with age and height percentile for boys and girls.
Table 2: Blood pressure levels for boys by age and height percentile.

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Table 3: Blood pressure levels for girls by age and height percentile.

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[Table 4] shows the regression coefficients of BP regression models, which was used to estimate the SBP and DBP by giving the age and height percentile at the Z-score scale. [Table 5] and [Table 6] show the comparison of BP levels for Saudi and North American children by age and height percentile.
Table 4: Regression coefficients from blood pressure regression models.

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Table 5:

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Table 6:

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   Discussion Top


In this study, we showed the age, gender, and height-related BP reference standards of preschool children in Saudi Arabia using oscillometric techniques. Our findings revealed that SBP and DBP are higher by 4-11 mm Hg in Saudi children than in American children of the same height percentile and age for both sexes. Thus, the United States-based BP standards cannot be generalized to all children.

Regular measurement of BP in children can detect both early essential and secondary HTN. Automated oscillometric devices provide easy and accurate measurement of BP.[22] However, the definition of normal BP in childhood is based on mercury sphygmomanometry.[1],[19],[20],[21] Misinterpretation of the Korotkoff sounds may lead to inaccurate BP readings by mercury sphygmomanometry in children.[23],[24] To overcome this problem and to eliminate human error, we used automated oscillometric devices. These devices are easy to use and do not require auscultations.[2]

Currently, oscillometric devices are recommended to be used for BP screening in children, provided that these devices are validated for the pediatric agegroup.[1] Newer models of oscillometric devices produce estimation of BP that is very close to the measurement obtained by mercury sphygmomanometry.[25],[26]

For optimal results, we used oscillometric devices that fulfill the American Association for the AAMI criteria, and graded A for both SBP and DBP under the BHS protocol and recommended by the European Society of Hypertension.[18],[27]

BP readings performed in clinics may sometimes be higher than home measurements, which is a phenomenon known as “white coat HTN”.[28] To record the real normal BP of children and to eliminate the effect of the “white coat” phenomenon, we measured their BP at home, than in the clinic or school, which is more comfortable for the child.[17]

Most of the studies from which the working group task force derived their data are from a single measurement.[19] However, most of the recent epidemiological studies worldwide used the average of multiple BP readings that is closer to the basal BP levels.[5],[13],[16] In this study, BP measurements were based on the lower value among the two measurements taken with 5-min intervals. There was no need for additional effort to obtain more than two readings, once the child realized the painless and benign nature of the procedure.

In our presented data, it is clear that SBP and DBP increased with age and height percentile for boys and girls. For mean SBP and DBP values, there was no statistically significant differences between boys and girls, except for DBP at age two years.

In Saudi Arabia, the United States-based BP standards are widely used. As shown in [Table 5]a, [Table 5]b and [Table 6]a, [Table 6]b, American children are taller and have lower BP than Saudi children of the same age-group, e.g. the 50th percentile of height in a two-year-old Saudi boy is 85 cm, whereas that for American boys of the same age is 92.1 cm.

Comparing the 2005 growth chart for Saudi children and 2000 CDC growth charts, El Mouzan et al concluded that the use of the 2000 CDC growth charts for Saudi children increases the prevalence of stunting and potentially leads to unnecessary investigations.[29] According to our observations in this study, SBP and DBP of Saudi children are higher by 4-11 mm Hg than those of American children of the same height percentile and age of 2-6 years for both sexes [Table 5] and [Table 6]. This may increase the prevalence of HTN and potentially lead to unnecessary investigations and treatments.

We believe that the US-based BP standards cannot be generalized to children in other parts of the world, because BP level and prevalence of HTN vary in different ethnic and racial groups; hence, some local BP standards were developed in several countries and regions.[5],[7],[9],[12],[14],[15],[16]

The presented data on BP standards based on age, gender, and height for pre-school children are recent, comprehensive, and nationwide representative of the Saudi population. These reference data are helpful for practicing clinicians to accurately assess their patients’ BP than based their assessments on the respective standards of other populations.


   Conclusion Top


This study adds evidence to the BP variations between different populations with influences such as genetic, environmental, and ethnic factors. The need of every population to define its normal standards is essential to accurately evaluate the BP of children.

Conflict of interest: None declared.



 
   References Top

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Al Salloum AA, El Mouzan MI, Al Herbish AS, Al Omar AA, Qurashi MM. Blood pressure standards for Saudi children and adolescents. Ann Saudi Med 2009;29:173-8.  Back to cited text no. 17
    
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O’Brien E, Waeber B, Parati G, Staessen J, Myers MG. Blood pressure measuring devices: Recommendations of the European Society of Hypertension. BMJ 2001;322:531-6.  Back to cited text no. 18
    
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Samuels JA, Bell C, Flynn JT. Screening children for high blood pressure: Where the US Preventive Services Task Force went wrong (Editorial). J Clin Hypertens 2013;15: 526-7.  Back to cited text no. 22
    
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Elkasabany AM, Urbina EM, Daniels SR, Berenson GS. Prediction of adult hypertension by K4 and K5 diastolic blood pressure in children: The Bogalusa heart study. J Pediatr 1998;132:687-92.  Back to cited text no. 23
    
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El Mouzan MI, Al Herbish AS, Al Salloum AA, et al. Comparison of the 2005 growth charts for Saudi children and adolescents to the 2000 CDC growth charts. Ann Saudi Med 2008;28:334-40.  Back to cited text no. 29
    

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Correspondence Address:
Abdullah A Al Salloum
Department of Pediatrics, College of Medicine, King Saud University, King Saud University Medical City, P. O. Box: 2925, Riyadh 11461
Kingdom of Saudi Arabia
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DOI: 10.4103/1319-2442.308337

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  [Table 1], [Table 2], [Table 3], [Table 4], [Table 5], [Table 6]



 

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