Cardiology Letters 2011, 20(3):207-214

Overestimated effect of body height on blood pressure in National Blood Pressure Education Program (NHBPEP) classification

Regecová V¹, Šimurka P², Kellerová E¹, Jurko A jr.³

¹ Ústav normálnej a patologickej fyziológie SAV v Bratislave

² Pediatrickej klinika FN v Trenčíne a 3Detská klinika JLF UK v Martine, Slovenská republika

Aim: The aim was to analyze the percentile distribution of blood pressure (BP) values according in order to body height and age in representative groups of 11 and 17 years (y) old boys (B) and girls (G) in Slovakia to point out some pitfalls in the routine application of the National High Blood Pressure Education Program on High Blood Pressure in Children and Adolescents (NHBPEP) standards. The work is also focused on the questions to what extent can the percentile distribution of BP and thus the classification into prehypertension and hypertension category be influenced by varying proportions of obese individuals with evidently higher BP.

Patients and Methods: The analysis of data includes 15448 children and adolescents aged 11 and 17 y examined in out-patient units for children and adolescents. BP was measured by mercury sphygmomanometry 3 times in a session (the average of the 2nd and 3rd measurement was evaluated). BP values were compared in subgroups stratified with regard to percentiles (P) of height, weight and body mass index (BMI) according to WHO 2001 standards, by a two-way ANOVA and regression analysis. In each age group the median value, 90th and 95th P separately for boys and girls were calculated and compared with the corresponding NHBPEP data.

Results: At the age of 11 y the regression analysis showed a significant (p<0.001) relationship of BP to body height, R2 = 3.76 in B and R2 = 3.5 in G. The tightness of this correlation decreased at the age of 17 y to R2 = 1.3 (B) and to R2 = 0.9 (G). Multifactor regression analysis confirmed a dominant influence of body weight on BP values R2 = 9 (B), R2 = 7.2 (G) in 11 y old children and R2 = 5.2 (B), R2 = 4.2 (G) in adolescents aged 17 y. Significantly (p<0.001) higher BP values in obese children shifted the percentile distribution to the right. Therefore we reanalyzed the distribution of BP in subjects with normal BMI within its 5th-95th P range according to WHO criteria. The mean differences of BP in 11-year-old children with the body height at the margins of distribution (>10 P and < 90.P of height) were 6 mmHg (B) and 5 mmHg (G) and diminished in 17-year-old adolescents to 2 and 3 mmHg respectively. Stratification of BP by body height did not show such a steady and steep rise in BP with body height, as presented in NHBPEP, where the reference BP values for short and tall individuals of the same age differed up to 8-9 mmHg. When compared to NHBPEP, in our sample the median BP values were somewhat higher, but in tall subjects the 90th and 95th P values were by 2 resp. 7 mmHg lower. At the age of 17 y 52% of B and 30% of G exceeded the ESH limit of optimal systolic blood pressure for the adults.

Conclusion: From the analysis of BP in a large sample of juveniles it follows i) that the maximal dispersion of BP values according to body height in the same age group has not to exceed 6 mm Hg; ii) varying proportions of obese children in the population involve important issues for estimation of the normal blood pressure ranges in healthy children and adolescents.

Keywords: blood pressure; body height; percentile values; NHBPEP classification

Published: March 1, 2011  Show citation