An epidemiological study of primary hypertension in children and adolescents 5 to 18 years of age in a rural Newfoundland community

Balram, B. Christofer M. (1978) An epidemiological study of primary hypertension in children and adolescents 5 to 18 years of age in a rural Newfoundland community. Masters thesis, Memorial University of Newfoundland.

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Abstract

An epidemiological study of primary hypertension in children and adolescents attending school in a rural Newfoundland community was carried out in 1977. Blood pressure measurements of 320 subjects 5-18 years of age were taken with a Physiometrics Automatic Blood Pressure Recorder. Of these 320 subjects, 68 had had their blood pressure measured two years earlier with an Arteriosonde 1010 recorder. The blood pressure values of these 68 subjects were used to study the ”tracking" of blood pressure by plotting a scattergram and obtaining linear egression statistics. -- Subjects were grouped into two year age groups and their blood pressure readings adjusted for age and sex and expressed in standard deviation unit (SDU) or scores. -- SDU scores ≥1 to <2 were considered as “high normal” and used to identify prospective hypertensives. SDU scores ≥2 were used to identify hypertensives. -- The familial aggregation of blood pressure was studied using the Analysis of Variance (ANOVA) technique. -- Blood Pressure readings for two year age groups were correlated with eleven factors. These were: height, weight, Quetelet Index, triceps skinfold thickness, subscapular skinfold thickness, upper arm circumference, resting heart rate, amplitude of P wave in lead II, amplitude of R wave in lead II, family size and birth order. -- Multiple linear regression analysis was carried out for children in the 5-12 and adolescents in the 13-18 year age groups. This division was made to ascertain whether the determinants of blood pressure levels might be different for children and adolescents. Blood pressure in SDU was the dependent variable and the eleven factors listed above were the independent variables. The data on three of these independent variables, height, weight, and Quetelet Index were converted to SDU. The level of statistical significance was chosen as p ≤0.05. -- The following results were obtained: -- (a) 14.4% of the 320 subjects had "high normal" systolic blood pressure with SDU scores ≥1 to <2 and 15.3% had “high normal” diastolic (4th phase) blood pressure with SDU scores ≥1 to <2. 1.6% had systolic hypertension with SDU scores ≥2. 1.6% had diastolic hypertension with SDU scores ≥2. -- (b) There was a strong significant tracking of systolic blood pressure. The regression coefficient of follow-up systolic blood pressure on initial systolic blood pressure was 0.53 (p <0.00002). A significant tracking effect of diastolic (4th phase) blood pressure was also obtained. The regression coefficient of follow-up diastolic (4th phase) blood pressure on initial diastolic (4th phase) blood pressure was 0.19 (p <0.05). -- (c) A significant aggregation of systolic (p <0.01) and diastolic (p <0.01) (4th phase) blood pressure within families was found for subjects 5-18 years of age. -- (d) Correlation analysis showed that systolic blood pressure was positively correlated with amplitude of P wave in lead II and amplitude of R wave in lead II in all age groups of each sex. Diastolic (4th phase) blood pressure was positively correlated with height, triceps skinfold thickness, resting heart rate, amplitude of P wave in lead II and amplitude of R wave in lead II in all age groups of each sex. -- (e) Multiple linear regression analysis showed that resting heart rate and amplitude of P wave in lead II were significant positive predictors of both systolic and diastolic (4th phase) blood pressure in the 5-12 and 13-18 year age groups. The amplitude of the R wave in lead II was a significant positive predictor of systolic blood pressure in the 5-12 and 13-18 year age groups. -- The findings relating amplitude of P wave in lead II and amplitude of R wave in lead II to blood pressure levels in children and adolescents is, to the author's knowledge, new and have never been reported before.

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