Prevalence of arterial hypertension in children and adolescents in Latin America: a systematic review and meta-analysis

INTRODUCTION

Hypertension (HTN) in children and adolescents is a growing public health problem. It is associated with an increased morbidity and mortality in the short and long term and is usually underdiagnosed and undertreated.¹ The global prevalence of HTN in children and adolescents seems to be increasing as a result of concomitant diseases that facilitate its development, such as cardiac or renal diseases or even sedentary lifestyles, obesity and the excessive dietary intake of salt and alcohol by children and adolescents.^2,3

Hypertension continues to be the leading contributor to disability-adjusted life years and the main modifiable risk factor for other cardiovascular diseases, disabilities and death worldwide.⁴ Although it is recognised as a prevalent disease in adulthood, it is becoming increasingly important in the paediatric age group, because in addition to the progressive increase in prevalence in this population evinced by several studies,^5,6 evidence has also emerged that at least half of adults with HTN had high blood pressure during childhood or in their youth.^7,8

The World Health Organization (WHO) estimates that HTN affects more than 1000 million people worldwide and causes more than 9 million deaths per year.¹ In children and adolescents in particular, recent publications have estimated a global prevalence of HTN in 2018 of approximately 4% (95% confidence interval [CI]: 3.29% to 4.78%), with a prevalence of approximately 3.02% in the American continent (95% CI: 2,24 to 3.90).⁹ This is below the prevalence reported in other continents, like Africa or Europe (6.94% and 4.09%, respectively).⁷

Despite the ample body of scientific evidence currently available on the subject, the prevalence of HTN in children and adolescents in Latin America remains unknown. Therefore, we carried out a systematic review and meta-analysis of the literature with the aim of determining the prevalence of HTN in children and adolescents in Latin America, as well as its distribution by sex, age and geographical area.

MATERIAL AND METHODS

Search strategy

The systematic review and meta-analysis were carried out applying the Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) checklist.¹⁰ The protocol of the study was registered at the inception under registration number CRD42020218408 in the PROSPERO register of the University of York.

The search was carried out independently by the researchers in November 2020 through the MedLine, Embase, Lilacs, Scielo, MedCarib and Google Scholar databases. The search strategy included terms in Spanish, English and Portuguese: (Prevalencia) AND (Hipertensión arterial OR Presión arterial elevada OR Presión arterial alta) AND (Niños OR Adolescentes), (Prevalence) AND (Hypertension OR High blood pressure OR Elevated blood pressure) AND (Children OR Adolescents), (Prevalência) AND (Hipertensão OR Pressão alta) AND (Crianças OR Adolescentes). No restrictions were placed on the year of publication. The full search strategy in these databases is detailed in Table 1.

To be included in the systematic review, articles had to correspond to primary studies with a population-based, cross-sectional or baseline cohort study design and establish the prevalence of HTN in individuals under 18 years in Latin America. Studies carried out in individuals aged more and less than 18 years were only included if they stratified the data to report the prevalence of HTN in the paediatric population. We excluded all primary studies with samples that were not representative of the general paediatric population, with methodological flaws or with evidence of poor quality.

We selected studies that specified the methods used to measure blood pressure and the criteria applied to diagnose HTN, and excluded those that did not. In addition, during the quantitative synthesis, in order to avoid overestimating the prevalence of HTN, we excluded all studies in which a minimum of 3 separate measurements of blood pressure had not been made as well as those applying definitions of HTN different from the one used in our systematic review (Table 2).

Data extraction and quality assessment

The data were retrieved independently by 4 different researchers. The following information was collected from each study: first author, country and year the study was conducted, sample size, age range of participants, geographical area where it was conducted, absolute and relative frequencies of male and female participants, absolute and relative frequencies of participants from rural and urban settings, applied diagnostic criteria, type of sphygmomanometer used to measure blood pressure, number of blood pressure measurements made and prevalence of HTN, overall, by sex and by geographical area. We referred to missing data and data not provided by the authors as not available (NA).

We rated the quality of the methodology and the data applying the Strengthening the Reporting of Observational Studies in Epidemiology (STROBE) guidelines.¹¹ The adherence to the 22 items can be consulted in Table 3. Discrepancies were assessed by a third researcher.

Data analysis

We carried out a meta-analysis to obtain an overall prevalence. We did subgroup analyses by sex, geographical area, country and time period (before 2005, between 2005 and 2010 and after 2010).

We performed the statistical analysis with the METAPROP command in the software Stata, version 11.2®, to analyse a collection of articles that reported the prevalence of HTN in children and adolescents in Latin America. We assessed statistical heterogeneity by means of the I² statistic for a level of significance of 5%. We used a random effects model to estimate the combined prevalence and the corresponding 95% CI with the DerSimonian and Laird method. We used the Freeman-Tukey arcsine transformation so that studies that reported proportions near 0 or 1 would not have to be excluded from the meta-analysis. We assessed for publication bias by means of Egger’s test.

RESULTS

Results of the systematic review

The searches in the databases yielded 6437 potentially relevant articles, of which 1292 were duplicates and therefore excluded. Applying the selection criteria, 4894 articles were eliminated after the perusal of the title and abstract, leaving 251 potentially eligible articles. After reviewing the full text of these articles, 174 were excluded for various reasons. In the end, the quantitative analysis of the systematic review and the meta-analysis included 77 primary studies. Figure 1 presents a flowchart of the article selection process.

Characteristics of included studies

The included primary studies were carried out between 1988 and 2020 in individuals under 18 years living in urban and/or rural settings in 12 Latin American countries: Argentina (10), Brazil (35), Chile (2), Colombia (6), Costa Rica (2), Cuba (8), Ecuador (1), Mexico (9), Paraguay (1), Peru (1), Uruguay (1) and Venezuela (1). The study with the largest sample included 73 399 participants and the smallest, 118. When it came to the sex distribution, there was a predominance of female participants in most study, who amounted to 54% of the cumulative studied population. Based on the type of setting, 88% of the studies were conducted in urban areas (68), only 4 were conducted in rural populations, and 5 were conducted in both urban and rural settings.

The most widely used definition of HTN in the reviewed studies was the one proposed in The Fourth Report on the Diagnosis, Evaluation, and Treatment of High Blood Pressure in Children and Adolescents.¹² In 60% of studies, the aneroid sphygmomanometer (23) and the automated sphygmomanometer (23) were the main devices used to measure blood pressure. On the other hand, in 86% of the primary studies, 3 separate blood pressure measurements were performed to establish the diagnosis of HTN, compared to 4 measurements in 12% and 5 to 9 measurements in the remaining 2%. Table 3 presents the general characteristics of all the primary studies in more detail. Table 4 presents the results of the assessment of the quality of the studies based on the STROBE statement.

Prevalence of HTN in children and adolescents

The prevalence of HTN in children and adolescents in Latin America ranged from 0.7% to 40.5%, with an overall prevalence of 8% (95% CI: 7 to 9%) (Fig. 2). There was clear heterogeneity between studies (I² = 97.49%; χ² = 3028.93; degrees of freedom [df] = 76; p <0.001). Upon visual inspection, the cone chart evinced asymmetry and Egger’s test suggested the presence of publication bias in the selected studies (p <0.001).

In relation to sex, the prevalence of HTN was higher in male individuals. The prevalence in the female paediatric population of Latin America ranged from 0.8% to 38.7%, with an overall prevalence of 8% (95% CI: 7 to 9%) (Fig. 3). In the male paediatric population of Latin America, the prevalence ranged from 1.4% to 42.3%, with an overall prevalence of 10% (95% CI: 8 to 12%) (Fig. 4). When it came to the residential setting, we found that the prevalence of HTN was higher in the urban paediatric population  of Latin America compared to the rural population: 8% (95% CI: 7 to 9%) vs. 4% (95% CI: 2 to 7%) (Fig. 5).

In the analysis by country (Fig. 6), Ecuador had the highest prevalence of HTN in the population under 18 years in Latin America, and Peru the lowest.

On the other hand, the subgroup analysis by time period evinced that the prevalence of HTN in children and adolescents was 9% before 2005 (95% CI: 6 to 13%), 7% between 2005 and 2010 (95% CI: 5 to 9%) and 8% after 2010 (95% CI: 7 to 10%) (Fig. 7).

DISCUSSION

In this systematic review and meta-analysis, we summarised the findings of 77 studies that included a total of 118 821 children and adolescents in Latin America, evincing an overall prevalence of HTN of 8%. This study is the first source of scientific evidence of HTN in the population under 18 years in this region of the American continent.

The reported prevalence in the paediatric population of Latin America exceeded not only the estimated global prevalence but also the estimated prevalence for the entire American continent in a previous systematic review of worldwide scope, which were 4.00% (95% CI: 3.29 to 4.78) and 3.02% (95% CI: 2.24 to 3.90), respectively.⁹

When we compared Latin America to other continents, the prevalence of HTN in children and adolescents was greater compared to the prevalence of 5.5% found in Africa (95% CI: 4.2 to 6.9)⁷, of 4.09% in Europe (95% CI: 2.96 to 5.39),⁹ of 3.10% in Southeast Asia (95% CI: 1.47 to 5.28)⁹ and of 4.64% in the Western Pacific Region (95% CI: 2.52 to 7.36).⁹

The quantitative analysis by sex evinced that in Latin America, the prevalence of HTN is higher in the male compared to the female paediatric population, which was consistent with the findings of other studies,^13-16 particularly those by Song P et al.,⁹ who reported a prevalence of 4.65% (95% CI: 3.80 to 5.58) vs. 4.46% (95% CI: 3.46 to 5.58) worldwide, and by Wang l et al.,¹⁷ who reported a prevalence of 10.6% (95% CI: 8.5 to 12.8) vs. 8.3% (95% CI: 5.9 to 11) in China. However, the opposite has been found in the paediatric population in Africa: 7% (95% CI: 5.2 to 9) vs. 6.4% (95% CI: 4.6 to 8.5).⁷

Previous studies have found that the prevalence of HTN is higher in the paediatric population of urban areas compared to rural areas.^9,17,18 The same pattern emerged in our systematic review and meta-analysis. This could be explained by the urbanization process, which has been found to facilitate the development of cardiovascular morbidity, as the population in urban areas has more and easier access to processed foods rich in fat, carbohydrates and salt,^19,20 not to mention that, generally speaking, sedentary habits and excess weight are more prevalent in urban populations.^21-23

The quantitative analysis by year evinced that the prevalence of HTN in children and adolescents in Latin America has not changed significantly. However, it may have been higher before 2005, and more importantly, since 2010, it has increased by 1 percent point. This could be due to an increase in unhealthy dietary and lifestyle habits and the presence of comorbidities that promote the development of HTN, such as obesity or overweight and metabolic disorders in the child and adolescent population.

Limitations

The main limitation of this study is the substantial heterogeneity observed between the included studies. This could be explained by methodological differences in the research, such as the instrument used for blood pressure measurement, the number of measurements, the time of rest between measurements and the characteristics of the participants themselves (for example, a higher proportion of participants with overweight or obesity, a higher ratio of adolescents to children). Furthermore, our findings were limited because the data from the primary sources did not suffice to carry out a detailed analysis stratified by age or to identify other factors associated with HTN, such as excess weight, sedentary habits or substance use, among others.

CONCLUSIONS

Our study suggests that there is a high prevalence of HTN among children and adolescents in Latin America. This evinces the importance of recognising HTN as a serious and growing problem in the paediatric population, the correct diagnosis and treatment of which would have a positive impact on the health and therefore the quality of life of the global population in the short, medium and long term.

It also evinced that the epidemiology of HTN in Latin American children and adolescents could be considered more alarming, given that most of the population faces several barriers to health care access, has a low income and even has a lower educational attainment compared to the rest of America and the world. In this context, reliable estimates on HTN can help design and implement public health policies aimed at its adequate prevention, diagnosis and treatment and the reallocation of health care resources for the purpose.

CONFLICTS OF INTEREST

The authors have no conflicts of interest to declare in relation to the preparation and publication of this article.

ABREVIATURAS

HTN: hypertension · 95% CI: 95% confidence interval · NA: not available.

SUPPLEMENTAL MATERIAL

Table 1. Search strategy. Available at: https://pap.es/files/1117-4706-fichero/RPAP_1862_Tabla_1_EN.pdf

Table 2. Definition of arterial hypertension in children and adolescents. Available at: https://pap.es/files/1117-4706-fichero/RPAP_1862_Tabla_2_EN.pdf

Table 3. Characteristics of included studies. Available at: https://pap.es/files/1117-4706-fichero/RPAP_1862_Tabla_3_EN.pdf

Table 4. Quality assessment with the STROBE approach. Available at: https://pap.es/files/1117-4706-fichero/RPAP_1862_Tabla_4_EN.pdf

Figure 1. Flowchart of study selection. Available at: https://pap.es/files/1117-4853-fichero/RPAP_1862_Figura_1_EN.pdf

Figure 2. Global prevalence of HTN in children and adolescents of Latin America. Available at: https://pap.es/files/1117-4706-fichero/RPAP_1862_Figura_2.pdf

Figure 3. Prevalence of HTN in female children and adolescents of Latin America. Available at: https://pap.es/files/1117-4706-fichero/RPAP_1862_Figura_3.pdf

Figure 4. Prevalence of HTN in male children and adolescents of Latin America. Available at: https://pap.es/files/1117-4706-fichero/RPAP_1862_Figura_4.pdf

Figure 5. Prevalence of HTN in children and adolescents of Latin America, by geographical area. Available at: https://pap.es/files/1117-4706-fichero/RPAP_1862_Figura_5.pdf

Figure 6. Prevalence of HTN in children and adolescents of Latin America by country. Available at: https://pap.es/files/1117-4706-fichero/RPAP_1862_Figura_6.pdf

Figure 7. Prevalence de HTN in the paediatric population of Latin America by time period. Available at: https://pap.es/files/1117-4706-fichero/RPAP_1862_Figura_7.pdf

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