Prevalence of hypertension among high school students attending public schools in Nairobi

Abstract

Background: There is an emerging epidemic of Cardiovascular diseases in developing countries. Hypertension is one of the contributing risk factors. There is emerging evidence that hypertension tracks from childhood through adolescents into adulthood. The purpose of this study was to determine the prevalence of hypertension among school going adolescents of ages between 13 and 20 years. Methods: The cross sectional study was carried out in March to May 2011. A total of 30 day secondary schools were selected from 112 day schools in Nairobi. Nairobi is one of eight provinces in Kenya before division into counties. The study was done together with a study on prevalence of obesity among high school students by Munguti et al. The study was conducted using WHO instrument for stepwise surveillance of chronic disease risk factors (STEPS). Data on selected social demographic characteristic and lifestyle behaviors, as well as physical measurements such as weight, height, waist and hip circumference and blood pressure were collected through standardized procedures. Multiple linear regression analysis was performed to estimate the coefficient of variability of blood pressure due to selected social demographic and behavioral characteristics and physical measurements. Results: A total of 1300 students were enrolled in the study where 59% were male. 27 participants were excluded due to exclusion on age criteria, lack of consent, chronic disease and missing data. In the end 1273 participants were analyzed. The prevalence of hypertension was 30.6 % using the recommended cut offs from the 4th report ( ~95th percentile of blood pressure for age and sex.) If categorization was done using the adult criteria then the prevalence of hypertension would be 6.1 %. 29 participants reported that they were current smokers and most started at 14 years of age. 22% of the students had ever consumed alcohol. The prevalence of obesity was 2.5% with a mean BMI of 20.7. The level of physical activity in this population was high. Majority 79% had adequate physical activity (more than 30 minutes per day for at least 3 days in a week). There was a positive association of hypertension overweight, obesity and vigorous work related physical activity. Being underweight and age more than 18 years correlated negatively with hypertension. However, there was no statistically significant association of hypertension with gender, consumption of fruits and vegetables. Conclusion: The prevalence of hypertension is very high among adolescents attending day schools in Nairobi. The adult criteria maybe underestimate the real prevalence. There is an urgent need for strategies and programs to prevent and control hypertension among adolescents in Nairobi.