The authors reply: Age-, sex-, and height-based blood pressure reference charts, Yazd children 6–18 years, Iran

Thank you for the opportunity to respond to the issues the authors raised about our article. We appreciate their interest in our paper and taking the time to express their concerns.

In their letter to the editor, the authors noted the definition of hypertension in children and adolescents cited in our study. Our study of a subgroup of surveys described the distribution of blood pressure as percentiles based on sex, age, and length without defining hypertension. Based on fourth report on the diagnosis, evaluation, and treatment of the National High Blood Pressure Program working group in children and adolescents, children and adolescents with blood pressure levels of 120/80 mmHg or above but less than the 95th percentile should be considered prehypertensive [1].

The American Academy of Pediatrics defines prehypertension or elevated blood pressure based on the absolute cutoff point of 120/80 mmHg or the 95th percentile of blood pressure, whichever is lower [2]. We hope that this information on age-, sex-, and height-based blood pressure percentiles will be used as a reference for epidemiological aspects of blood pressure distribution other than hypertension for children and adolescents in our region.

According to the sample size calculation of this research as a substudy of a great survey, we assumed a prevalence of psychiatric disorders equal to 0.3, a type one error of 0.05, and an accepted error of 0.05, and the sample size for Yazd was calculated as 825. We suggested the design effect for cluster sampling of 1.2; thus, the final sample size increased to 990 (1,000). Finally, 1,035 people were selected for the project.

To address the issue of blood sampling between the 2 blood pressure measurements we saw during the pilot project, we performed the blood sampling between the blood pressure measurements to reduce the stress on the subjects.

The mean systolic and diastolic blood pressures in both sexes were based on age and only systolic blood pressure was significantly higher in boys than in girls (P[less than]0.0001). As seen in our study, boys had greater mean body mass index and height than girls, a difference that can induce higher systolic blood pressure in boys than in girls [3].

Reporting elevated blood pressure/prehypertension cases was not the goal of our research. We reported this in another study of hypertension prevalence in children and adolescents in Yazd city.

Footnotes

Conflicts of interest

No potential conflict of interest relevant to this article was reported.

Funding

This letter received no specific grant from any funding agency in the public, commercial, or not-for-profit sectors.

References

1. National High Blood Pressure Education Program Working Group on High Blood Pressure in Children and Adolescents. The fourth report on the diagnosis, evaluation, and treatment of high blood pressure in children and adolescents. Pediatrics 2004;114:555–76.

2. Flynn JT, Kaelber DC, Baker-Smith CM, Blowery D, Carroll AE, Daniels SR, et al. Clinical practice guideline for screening and management of high blood pressure in children and adolescents. Pediatrics 2017;140:e20171904. pmc pdf