Study of prevalence and determinants of hypertension among the urban school going children aged 10–15 years

Dear Sir,

Systemic hypertension (HTN) is the leading cause of death and disability worldwide. Although HTN is a problem of adults the etiological process and risk behaviors start early in life.^[1] Systemic HTN is estimated to cause 7.5 million deaths, about 12.8% of all deaths worldwide. Raised blood pressure among children and adolescents has shown tracking to adulthood. This tracking phenomenon appears strongest for systolic blood pressure (BP) but is also noted in diastolic BP.^[2],[3] The prevalence of childhood HTN varies from 1% to 16.2%^[4] and seems to be increasing. This rise is partially because of the increasing prevalence of obesity among children and adolescents.^[5] With globalization bringing more lifestyle modifications, adolescents are exposed to multiple risk factors, including obesity, diet, academic stress, and lack of physical work apart from hereditary risk factors. The combined effect of these factors is making children prone to developing HTN.^[6] In children measurement of BP is a neglected part of physical examination as most of the prevention and control strategies target adults. Early diagnosis of HTN is an important strategy in its control, effective treatment, and prevention of complications.^[7] Therefore, according to the recommendation of the fourth report from the National high BP education program working group, it is important to measure BP during routine physical examination of all children above 3 years of age.^[8] Primary or essential HTN is more common in adolescents and has multiple risk factors, including obesity and a family history of HTN. Secondary HTN is more common in preadolescent children, with most cases caused by renal disease.^[9] Since the risk factors for the development of HTN starts in childhood, pediatricians should be encouraged to include routine BP measurement in children.^[10]

This was a field-based observational study carried out to study the prevalence and determinants of HTN among school going children aged between 10 and 15 years in Hyderabad from March 2014 to April 2015. The height and weight of every child were measured to calculate the body mass index (BMI) using standard techniques. The height was measured while the subject is standing upright and barefoot, using a standard vertical calibrated bar and a sliding pointer with an accuracy of up to 0.5. The weight was recorded using standard floor weighing machine with the degree of accuracy to the nearest of 0.5 kg and the subject asked to dress lightly and remain barefoot. The BMI = weight in kg/height in m ². The socioeconomic status was classified according to modified Kuppuswamy scale of social classification. Children consuming junk and oily foods more than 3 times a week were taken as having the habit of eating junk and oily food.

The standard methodology as recommended by the fourth report on the diagnosis, evaluation, and treatment of high BP in children and adolescents was used to measure the BP. The children were divided into groups of ten each and taken to a separate and silent room. The procedure was explained in detail and the children were assured that the procedure would be neither painful nor harmful. All efforts were made to eliminate factors which might affect the child’s BP such as anxiety, fear, crying, laughing, and recent activity. Every effort was made to record the BP under simulated “basal” or “near basal” conditions. The BP was recorded only when the child had become accustomed to the observer, instrument, and surroundings. The child was allowed to rest for 5–10 min and then the BP was recorded in sitting position with the back supported, feet on the floor and right arm supported with cubital fossa at heart level. The right arm was used for consistency and for comparison with standard tables and because of the possibility of coarctation of the aorta, which might lead to false (low) readings in the left arm.^[2] BP readings were expressed to the nearest 2 mm Hg. Two BP readings were taken from each child at 0 and 30 min using the auscultatory method. The average of the two readings was taken as BP of the individual. Those children in whom BP was found to be abnormal for his/her age, were re-examined after 1 week. Final BP reading obtained was taken the BP of that child. All the BP recordings would be taken at the same time of the day, i.e., afternoon hours and recorded by the same person with the same instrument. The systematic examination was carried out to exclude cardiovascular, renal and other diseases which could affect BP.^[2] A detailed history was taken in a predesigned proforma and the data thus obtained were compiled and analyzed.^[3]

A total of 514 children in the age group of 10–15 years were studied. The total number of female children was 268 (52.1%) and male children were 246 (47.9%); of which 73 (14.2%) were underweight, 406 (78.9%) were normal weight, 31 (6.0%) overweight and 4 (0.8%) obese. The third screening revealed a total of 102 children with abnormal BP, of which 50 children were males and 52 were females. The overall prevalence of pre-HTN and HTN in this study was 11.5% and 9.7%, respectively. Prevalence of systolic and diastolic HTN in this study was 7.8% and 5.3%, respectively. Prevalence of pre-systolic and pre-diastolic HTN was 5.6% and 7.8%, respectively. Weight and increased BMI were found to have statistically highly significant association with HTN. The height of the child did not have a significant association with HTN. Prevalence of pre-HTN and HTN in obese and overweight children was 45.7% and 40%, respectively. Prevalence of pre-HTN and HTN in nonoverweight children was 9.0% and 7.5%, respectively. Obese and overweight children were found to be five times more prone to HTN when compared to other children. Statistically highly significant association between BMI, pre-HTN and HTN (Fisher exact test statistic value is 0. The result is significant at P < 0.05). Prevalence of pre-HTN in underweight children was 8.2%. HTN was not found in underweight children. Prevalence of pre-HTN and HTN were found to be more in the mid-adolescents compared to early adolescents. There was statistically significant relation between age and pre-HTN (the Chi-square statistic is 5.125. The P = 0.023583. This result is significant at P < 0.05). However, there is statistically no significant association between age and HTN (Chi-square statistic is 1.675. P =0.195596). Prevalence of HTN was more in boys when compared to girls whereas the prevalence of pre-HTN was slightly more in girls when compared to boys. However, statistically no significant relation was found between sex and pre-HTN (Chi-square statistic is 0.0003. P =0.98678) and HTN (Chi-square statistic is 1.2678. The P = 0.260181). The prevalence of pre-HTN and HTN were more in private school children when compared to Government school children. A statistically high significant relation was found between type of school and HTN (Chi-square statistic is 8.3827, P = 0.003788). However, there was no statistically significant relation between school and pre-HTN (Chi-square statistic is 1.2648, P = 0.260735). There was statistically highly significant relation found between socioeconomic status and HTN (Chi-square statistic is 10.3703, P = 0.001281). Children belonging to high socioeconomic class showed a higher prevalence of HTN compared to children of low socioeconomic class. There was statistically significant relation found between family history of HTN and prevalence of HTN (Chi-square statistic is 3.9043, P = 0.048163), but not much correlation between a family history of HTN and pre-HTN. The prevalence of pre-HTN and HTN was more in children eating junk and oily food when compared to other children [Figure 1] and [Figure 2].

The prevalence of pre-HTN and HTN in this study was found to be 11.5% and 9.7%, respectively. This indicates that HTN in school aged children is a major public health problem and immediate intervention is needed. There was almost equal distribution between male and female children out of the 514 students studied. The prevalence in various other Indian studies ranges from 0.46% to 11.9%. This wide difference may be due to different standards used for diagnosis of HTN and also due to regional variation. There could be a higher prevalence of HTN in southern India probably because of influential factors like genetic inheritance, dietary habits, and lifestyle factors. The distribution of HTN across three screenings showed a reduction in the prevalence of systolic HTN from 17.8% to 13.4% and that of diastolic HTN from 16.5% to 13%. This result confirms the need for repeated measurements of BP to make an accurate diagnosis of HTN. The overall prevalence of pre-HTN was 11.5% and HTN was 9.7%. In our study, a positive correlation with weight, BMI and pre-HTN and HTN was found. There was no significant association between height and pre-HTN and HTN. In our study, prevalence of pre-HTN and HTN were more in mid-adolescent age group when compared to early adolescent age group. In our study, the prevalence of pre-HTN and HTN in boys was 11.4% and 11.4%, respectively, whereas prevalence of pre-HTN and HTN in girls were 11.6% and 8.2%, respectively. The prevalence of pre-HTN and HTN were more in private school children when compared to government school children. There was statistically significant relation between school and HTN, but no association was found between school and pre-HTN. Our study showed that prevalence of pre-HTN and HTN were more in children with family history of HTN when compared to other children. We found that hypertensives in our study spent more time in watching TV and less time in physical activity than nonhypertensives; however, it did not reach statistical significance. The prevalence of pre-HTN and HTN were more in children eating junk and oily food when compared to other children. The prevalence of pre-HTN and HTN were more in children belonging to high socioeconomic class when compared to children of low socioeconomic class [Table 1] and [Table 2].

Table 1: Prevalence of different grades of hypertension Click here to view

The prevalence of HTN among the adolescent age group was alarmingly high. There is much difference in prevalence of pre-HTN and HTN among many studies. Awareness about HTN was very low among the study participants. The prevalence of pre-HTN and HTN in our study was 11.5% and 9.7%, respectively. The prevalence of pre-HTN in boys and girls were 11.4% and 11.6%, respectively; whereas the prevalence of HTN in boys and girls were 11.4% and 8.2%, respectively. The prevalence of pre-HTN and HTN in overweight and obese children was 45.7% and 40% respectively which was five times more than normal children. In our study, there was significant statistical association found between weight, BMI, school, family history of HTN, socioeconomic status, dietary habits, and HTN. Statistically significant association was not found between age, sex, height, and HTN. Statistically significant association was found between weight, BMI, age, and pre-HTN. Prevalence of pre-HTN was not affected by sex, height, school, family history of HTN, dietary habits, and socioeconomic status. This study concluded that overweight, family history of HTN, private school study, high socioeconomic status and children eating junk and oily foods were the significant predictors of HTN.

Acknowledgments

The authors are thankful to all the school children and their legal guardians for their cooperation and participation in this study. We express our gratitude to Dr. KRP, BDS, Medical writer, for making significant language and technical revisions to the manuscript and for final script editing.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

Source of Support: None, Conflict of Interest: None

DOI: 10.4103/1755-6783.193958

[Figure 1], [Figure 2]

[Table 1], [Table 2]