The study was a cross-sectional study conducted from April 2014 to August 2015 among students of various government high schools at Patna, Bihar, India of adolescent age group studying in eighth, ninth and 10^th standards.

Considering, 11.7% prevalence of HT among school children [4] with 15% relative error, the sample size was calculated to be 1342 by using the formula N=4pq/L². Taking the design effect of two into account and non-response of 10%, the sample size comes out to be 2952.

Sampling Method: All government schools in Patna district were considered eligible for the study. The study subjects were drawn by two stage stratified cluster sampling, the strata being schools and classes in the schools. The students of class eighth, ninth and 10^th standard were taken for the study. Fifty students from each class were randomly selected from the list of students for each class. So, total 150 students were selected from each school. Finally, 3000 students from 20 schools were enrolled and interviewed for the study. In the process of data entry 87 data were incomplete so those were excluded from final analysis. Finally, data of 2913 students was analyzed.

Study Instruments: A pre-designed, pre-tested, semi-structured, self-administered questionnaire, containing identification data i.e., age, sex and class, questions pertaining to risk behavior in relation to cardiovascular diseases. The questions pertaining to awareness and risk behavior in relation to CVD were taken from WHO’s Global School based Student Health Survey (GSHS), which includes questions on eating behavior (like eating junk food, etc.,), physical activity, obesity, tobacco, alcohol use and their awareness about these [14]. In addition, questions were designed for awareness about high salt intake and skills in avoiding all these risk factors. The questionnaire was translated into Hindi by a trained Hindi translator. The questionnaire was pre-tested in both languages on twenty students in government schools and suitable modifications were done before finalization. The questionnaire was self administered and the investigators were present to solve any query at the time of filling up of questionnaire by students.

All adolescents were clinically examined with special emphasis on evaluation of cardiovascular system. Anthropometric measurements were recorded as per the recommendations [15]. The weight was recorded to the nearest 0.1 kg by weighing scale and the height was noted to the nearest 0.5 cm using a measuring scale. BMI was calculated by the formula: BMI=Weight (in kg)/ Height (in m²). Then all the students were classified according to BMI scores using CDC 2000 classification for BMI for age for children into Underweight, Normal and Overweight/Obese. Underweight was defined as BMI-for-age less than fifth percentile and overweight as more than 85^th percentile while obese if BMI was more than 95^th percentile of reference. Normal BMI-for-age was taken as values equal or more than fifth percentile but equal or less than 85^th percentile of the reference data.

BP was measured using standardized sphygmomanometers with appropriate size cuff. The BP was measured with the child in a sitting position, mostly at the end of interview session, so that students remain relaxed. The cuff was inflated to a level at which the distal arterial pulse was not palpable. It was then deflated at a rate of 2-3 mmHg per second. In this way, systolic and diastolic blood pressures were recorded. Three BP readings of each student were taken at two minutes intervals. The average of the three readings was recorded for both systolic and diastolic blood pressures of each student. All the three readings were taken by the same trained person.

Blood pressure is taken as normal when systolic and diastolic blood pressure is <90^th percentile for gender, age and height. Pre HT is defined as Systolic Blood Pressure (SBP) or Diastolic Blood Pressure (DBP) between the 90^th and 95^th percentile. Adolescents having blood pressure >120/80 mmHg, but below the 95^th percentile were also included in this category. HT is defined as SBP or DBP exceeding the 95^th percentile for age, gender, and height [16].

The data was entered and analyzed by using SPSS software version 22.0. Simple frequency and percentage were used wherever required. Chi-square test was applied to see the significance for categorical variables. Mean systolic and diastolic blood pressure was calculated for boys and girls and for different age. Analysis of variance (ANOVA) test was applied to see the significance of distribution of blood pressure among students in different age. Pearson correlation co-efficient was used to see the correlation among systolic and diastolic blood pressures, body weight, height and BMI. The p-value for significance was set at 0.05.

The study protocol was approved by ethical committee of All India Institute of Medical Sciences (AIIMS), Patna. A prior consent for the study was taken from school administration and from the parents. At the time of the initiating the study each participant was informed about the study protocol and informed consent was obtained.

The present study included 2913 adolescents which included 1168 males (40.1%) and 1745 females (59.9%). Total prevalence of HT in our study was 4.6%. The prevalence of pre-HT was 10.9%. Prevalence of HT in males was 5.0% and in females was 4.3%. We observed that prevalence of HT increases with age and it was significant statistically (p<0.01) [Table/Fig-1].

For the boys, the prevalence of HT among underweight was 1%, among normal was 6%, among pre-obese was 12.5% and among obese was 33.3%. For the girls the prevalence of HT among underweight was 1.9%, among normal was 4.6%, among pre-obese was 7.7% and among obese was 8.3%. So, as we go from underweight to obese the percentage of HT increases [Table/Fig-2]. As the age increased the mean systolic blood pressure and mean diastolic blood pressure also increased which was significant statistically [Table/Fig-3,4].

The result revealed that systolic and diastolic BP have a positive correlation (p<0.01) with age. Correlation coefficient of systolic BP with age was found to 0.122, and that of diastolic blood pressures 0.122. Similarly, a positive and significant correlation of SBP and DBP were present with height and BMI [Table/Fig-4].

The proportion of adolescents who had ever chewed tobacco was 5.3% (9.0% among boys and 2.9% among girls), cigarette smoking 4.3% (8.3% among boys and 1.6% among girls), alcohol consumption 2.1% (3.8% among boys and 1.0% among girls), and excess salt intake was also quite high (22.3%). Majority of them were not doing physical activities for maintenance of good health [Table/Fig-5].

The present study was conducted to find the prevalence of HT and risk factors of cardio-vascular diseases among school going students. The prevalence of HT among school going adolescents in present study was 4.5%. It was 5.0% among boys and 4.3% among girls. Taksande et al., in their study in Wardha district, found prevalence of HT in children to be 5.75% [17]. Various studies reported prevalence of HT in children between 0.46% to 11.7% [4,18,19]. The reason for low prevalence of HT in some studies may be because of use of means and standard deviation for HT assessment rather than using the more acceptable criterion of 95^th percentile of BP-values. Chadha SL et al., in their study reported, prevalence of HT in school children was 11.7% [4]. Similarly, Anjana et al., reported prevalence of HT among boys and girls, as 8.33% and 6.52%, respectively [7]. Both the above studies were conducted in urban schools, where dietary habits and lack of physical activity could have contributed to a higher incidence.

In the present study, the SBP and DBP showed a positive correlation with age, height and BMI which is consistent with the previously reported studies on BP in children [20–23]. In the present study, both SBP and DBP show a significant correlation with increase in age, height and BMI but not with weight. Voors et al., reported that BP was correlated more closely to height and body mass than age [24].

The positive correlation of both systolic and diastolic blood pressure with height in the present study confirms the presence of primary HT among children and suggests that such children are at risk of developing HT at latter stages. The finding recommend that these children should be considered for high risk for developing CVD and type 2 diabetes and must be screened for a close follow up for modification of risk factors.

Healthy dietary patterns developed in childhood are important for prevention of Cardio-Vascular Diseases (CVD) in adulthood. The evidences regarding the effectiveness of long term dietary intervention for the reduction of risk factors for CVD in children is limited, but the available data suggest that changes in specific dietary macronutrients (e.g., dietary fat and carbohydrates) and micronutrients (e.g., sodium and calcium) have an impact on the risk of Cardio-vascular diseases [25]. Unhealthy dietary practices such as junk food and cold drink consumption, less vegetable and fruit intake was found in many school going students in present study. These habits should be prohibited from early age.

In the present study, only 34.8% adolescents were doing regular physical activity to maintain their health. Results of other observational studies on children and adolescents (4–18 years of age) and young adults (19–21 years of age) demonstrate associations between increased time spent in sedentary activities and decreased levels of physical activity, increased levels of obesity, related cardiovascular risk factors, including HT and insulin resistance. Longitudinal data from the Cardiovascular Risk in Young Finns Study and the Muscatine Study, similar to observations of adults, indicate that minimum cardiovascular risk profiles are seen in individuals who are consistently physically active [26,27].

In the present study, 5.3% of the adolescents have admitted to tobacco chewing which was almost similar to 3.05 percent as observed in another school based study by Prajapati et al., [27]. The children, who have tried tobacco in the present study, would have a high risk of becoming regular tobacco users in future, which would lead to an increase in their risk of developing CVD and other non-communicable diseases.

Regarding alcohol consumption, alcohol was seen to be consumed at least once by 3.8% of boys and 1.0% of the girls. In a similar study by Singh AK et al., in a private school of New Delhi, alcohol was seen to be consumed at least once by 30.1% of boys and 26.8% of the girls [28]. The higher percentage of alcohol consumption may be found due to metro culture and life style pattern of New Delhi.

Regarding extra salt in food/salad, it was seen that 24.4% boys and 21.0% girls were taking extra salts. A higher salt intake was also found in a study by Singh AK et al., in a school of New Delhi were 31.5% boys and 16.5% girls were consuming extra salt [28]. Prevalence of HT among school going adolescents from various part of India is shown in comparative table [Table/Fig-6].

In the present study, we had taken students of government schools in which mostly students of lower and middle socioeconomic group study. In the private and convent schools, mostly students of upper socioeconomic group study who have generally more unhealthy dietary practices related to CVD. So, the prevalence of HT might have increased if we had taken private and convent schools.

It is clear that risk factors for cardio-vascular diseases can develop during childhood and adolescence. These factors may be either genetic or environmental. When risk factors start to develop at an early age, they are likely to tail along as the age increases. This tracking is reinforced by ongoing and new adverse health behaviors. All children and adolescents must be screened regularly for blood pressure so that remedial measure can be initiated as early as possible. Restrictions on advertising, promotion, and availability of tobacco products, alcohol and junk foods to children and adolescents should be constituted. As a part of preventive strategies, schools must formulate policies for addressing junk foods consumed in the school premises as well as outside, for promotion of sports and recreational activities and for tobacco frees settings.