A STUDY ON THE PREVALENCE OF PREHYPERTENSION AMONG ADOLESCENTS IN TIRUNELVELI TOWN TAMILNADU

Objective: The prevalence of hypertensive disease among adolescents is increasing trend. This rise in hypertension (HTN) among adolescents is multifactorial. Prehypertension advances to HTN in due course in adult life, becoming one of the major risk factors for cardiovascular diseases later. We aim to determine the prevalence of prehypertension among adolescents in Tirunelveli town. Methods: One thousand high school children aged 14–18 years from Tirunelveli city were chosen. The blood pressures (BPs) (systolic and diastolic) were recorded using the standard technique. Physical biometrics was documented. Results: BP >90 th percentile is considered to be abnormal in adolescents. Prevalence of prehypertension is 0.7% (f-0%, m-0.7%), HTN is 4.7% (f-2.5%, m-2.2%), and cumulative abnormal BP is 5.4%. Among the 54 adolescents, only one had body mass index of overweight category surprisingly. Conclusion: Previous studies indicate approximately 3–4% of adolescents develop consistently elevated BP across many countries. The common causes attributed are physical inactivity, consumption of junk food, besides hormonal changes in adolescents. The results of our study indicate 5.4% of students having more than the 90 th percentile nearly corresponds to results of many studies. Early detection of prehypertension in adolescents is cost-effective measure that would further avoid impoverishment to the middle-income group as well as improve the quality and expectancy of life. Effective specific school health programs are needed at the time, especially in developing countries like India.


INTRODUCTION
Hypertension (HTN) is the leading cause of morbidity and mortality as well as premature death.The number of people affected by HTN globally was over 1 billion [1].Prehypertension, HTN accounts for nearly 85 lakh deaths worldwide indirectly through causing cerebrovascular accidents, ischemic cardiac disease, and renal diseases [2,3].Since HTN stands as one of the risk factors for cardiovascular diseases (CVDs) [4] unhealthy diet, lack of physical activity, tobacco use, obesity, abnormal blood lipid profile, elevated blood glucose, and stress.Long-term exposure to these factors leads to the progression toward the development of atherosclerosis, myocardial infarction, and stroke.In general, CVD risk factors are considered for the overall risk factor profile as suggested by the World Health Organization (WHO) HEARTS package [5]."HTN affects one in three adults worldwide" as per a report from the news report of the WHO [6].In 2021 HTN was the primary cause of nearly 6.9 lakhs of reported deaths in the United States of America (USA) as per a report from the Centre for Disease Control and Prevention government of USA [7].Prehypertension is the stage known to occur earlier than HTN concomitant with atherosclerosis and target organ damage [8].Life expectancy tends to decrease with prehypertension in adolescents, further compared to persons with HTN diagnosed at a late stage [9].High blood pressure (BP) has been attributed to left ventricular hypertrophy detected even in children, referred to as target organ damage.It imposes a considerable financial burden sometimes catastrophic expenditure of nearly 40% of their annual income to especially low and middle-income groups of the population done in a study in Mumbai, India [10].
As a systematic analysis showed, 31.3% of adults in the world had HTN in 2010.Levels of BP have been observed to track over time, and children with elevated BP (EBP) are more likely to become hypertensive adults.It is well understood that HTN in children could be considered merely a public health issue emerging in the last few decades as per available literature and studies.Identifying and treating such a high-risk group of prehypertension at an early stage would elude this impoverishment.Detection at an early age can avert a reduction of life expectancy in untreated conditions.Recording the BP once a year with the anthropometric parameters in adolescents may be recommended for early detection strategies as mentioned above.Adults diagnosed with HTN were found to have increased BP [11].
HTN is defined simply in adults as EBP (>120-129 mmHg systolic and <80 mmHg diastolic) or HTN (≥130 mmHg systolic and ≥80 mmHg diastolic).The 2004 4 th report submitted by the National Heart Lung Blood Institute (NHLBI) of USA (4 th R) defines abnormal BP as ≥90 th percentile (for age, height, and gender [AGH]), prehypertension as ≥90 th percentile but <95 th percentile (AGH), and HTN as ≥ 95 th percentile (AGH) at 3 separate visits.In adolescents, HTN is often undetected because they are generally healthy and seldom visit a physician unless there is an obvious illness.For this reason, routine measurement of BP among children and adolescents is recommended.Detecting adolescents with prehypertension and HTN would aid early treatment.Studies in recent times have demonstrated that the level and trend in BP vary from population to population.In fact, among children and adolescents, growth patterns, age, and gender strongly influence BP levels.Equally, sociodemographic factors, overweight, and obesity in children have been associated with high BP [12].Our study aims to determine the prevalence of prehypertension among adolescents in Tirunelveli district.

METHODS
This study is a cross-sectional study, involving 1000 adolescents from secondary schools around the area of Tirunelveli town.Subjects were selected by a multi-stage sampling method.Ethical clearance was obtained from the Institutional Ethics Committee.Healthy subjects were selected, while those with a history of wheezing, kidney diseases, or on medication for some other illness were excluded.Using pretest questionnaire demographic and anthropometric parameters were documented.Using age-specified international cutoff values for defining obesity and overweight were classified [13].American Heart Association recommendations were followed to record BP with a mercury sphygmomanometer [14].The first Koratkof sound was taken as systolic and the fifth sound as diastolic BP [15].An average of three readings was recorded in the datasheet.Prehypertension and HTN classification was done with a recommendation by the 7 th report NHLBI of USA as mentioned above [16].Those who were found to have high BP at the first visit were reviewed in the same venue after a week interval and followed the same procedure for staging as high BP classification.Analysis of the package was done with SPSS version 15.0.Unpaired Student's t-test was carried out to compare BP and other numeric variables.

RESULTS
The distribution of the study group is shown in Table 1, Figs. 1 and 2. The percentage of males and females is around 52.70% and 47.30%, respectively.The height, weight, and body mass index (BMI) were compared against systolic BP (SBP), and diastolic BP (DBP) in mean value (Tables 2-5), in various intervals of groups.Most of the subject's BMI falls under normal values and only 5% of the subject's BMI is increased which is around 25-30.SBP is measured for all the subjects.More than the 90 th percentile is taken as pre-hypertension; among 1000 subjects 54 adolescents had raised SBP above 90 th percentile.The percentage is around 5.40% (Tables 1 and 6 and Figs. 1 and 2).The prevalence of prehypertension and HTN was shown in the table below, respectively, 0.7% and 4.7% cumulatively 5.4% was reported with 1000 participants in this study.Similarly, for the same subjects, the DBP is also raised above the 90 th percentile (Table 7)."The National Family Health Survey reports have so far used the adult cut-offs for nutritional assessment for this age group; that is, those with a BMI <18.5 kg/m 2 are thin; BMI 25-29.9kg/m 2 are overweight and those with a BMI 30 kg/m 2 are considered obese [17][18][19]".
Among various ranges of height, males 136-140 cm have more increase in SBP than others (Table 8 and Fig. 3).
Among various ranges of weight in females range of 40-45 kg occurred a high proportion of increased SBP followed by more than 45-55 kg while in male participants, the proportion of high SBP was trendy until it reached maximum in the range 50-55 kg (Table 9 and Fig. 4).
In females, the BMI range of 20-25 got more proportion of increased SBP, while male participants' BMI of more than 25 had a maximum proportion of increased SBP compared to others (Table 10 and Fig. 5).The DBP changes also follows same pattern as above (Fig. 7), although Mean value of SBP, DBP considering only gender failed to show much difference (Fig. 6).
The mean value of SBP and DBP seem to have a lower number in the extreme height range, especially beyond 161 centimeters in both genders (Table 3).The same pattern has also been noticed in the mean value of SBP about weight ranges in both extremes in the female gender while in the male gender, no changes occur in extreme weight range value (Table 4).
For unknown reasons, females with overweight BMI were found to have lower mean SBP compared to other ranges of BMI of female participants as well as in male participants (Table 5).

DISCUSSION
The prevalence of pre HTN is 0.7% (F-0%, M-0.7%) and HTN 4.7% (F-2.5%,M-2.2%) in our study.The prevalence of HTN is similar to   Pre HTN.The same study showed a higher prevalence in females (6.9%) when compared to males (3.8%).Our study showed a minor difference in the prevalence of HTN in gender (Table 6) and 0% in pre HTN in females.A study by Ejike et al. [21] reported higher DBP in nonurban male adolescents compared to their urban counterparts, with association to higher BMI as attribution, though significant only in female participants.The difference in prevalence rates may be due to changing methodologies, varying criteria for diagnosis of HTN and geographic factors.The above studies suggest that the detection of HTN in adolescents is evident across many countries.The necessity of screening a healthy population seems evident in reports across countries.Early detection makes early treatment possible to achieve the ultimate goal of preventing target organ damage thereby.The     "Epidemiologic studies suggest that populations show a progressive increase in average BP as the distance from the equator increases (i.e., higher north) [22,23]."Our study did not consider such geographic factors although the study population are South Indian.Some chronic diseases such as nephritic syndrome, tumors of the adrenal gland, hypercholesterolemia, and chronic kidney disease may present as elevated BP at the very initial stage in due course of illness.We realize diagnostic criteria of measurement of BP more than the 95 th percentile for age, height, and gender would be appropriate as suggested by the 7 th report of JNC of NLHBI [16].

Fig. 4 :Fig. 3 :Fig. 5 :
Fig. 4: Percentage distribution of normal and high systolic blood pressures concerning various ranges of weight in both gender

Fig. 6 :
Fig. 6: Mean value of systolic and diastolic blood pressure in both gender

Percentage distribution of normal and abnormal diastolic blood pressureTable 3 : Mean value of SBP and dBP with standard deviation in various range of heights and gender Height (cm) Frequency The mean value of SBP±SD The mean value of DBP±SD
BP: Blood pressure, SD: Standard deviation, SBP: Systolic blood pressure, DBP: Diastolic blood pressure

Table 4 : Mean value of SBP and DBP with standard deviation in various ranges of weight and gender Weight (kg) Frequency The mean value of SBP±SD The mean value of DBP±SD
BP: Blood pressure, SD: Standard deviation, SBP: Systolic blood pressure, DBP: Diastolic blood pressure

Table 5 : Mean value of SBP and DBP with standard deviation in various ranges of BMI and gender BMI Frequency The mean value of SBP±SD The mean value of DBP±SD
BP: Blood pressure, SD: Standard deviation, BMI: Body mass index, SBP: Systolic blood pressure, DBP: Diastolic blood pressure the study results of Ujunwa et al. [20] like 5.4% of HTN and 17.3%

Table 10 : Distribution of normal blood pressure and high systolic blood pressure; their percentage ratio concerning various ranges of BMI in both gender
BMI: Body mass index