Calculator: Pediatric blood pressure Z-scores

This page is running a macro package for R hosted on a Shiny server. It calculates Z-scores for both systolic (SBP) and diastolic (DBP) blood pressure for children aged 2-18 years based on Appendix B in The Diagnosis, Evaluation, and Treatment of High Blood Pressure in Children and Adolescents 4th edition , from the NIH National Heart, Lung, and Blood Institute. Please note, the required height Z scores are first calculated using LMS tables from the CDC 2000 growth charts; these values are then used to calculate age-, height-, and sex-specific SBPz and DBPz using the 4th order polynomial formulae in Appendix B. In response to popular demand (Dan!), the code was revised 11/17 to output 5th to 99th percentile values for systolic (fxsys) and diastolic (fxdia) BP's for each patient (i.e. age-, height-, and sex-specific thresholds).

In August 2017, new AAP clinical practice guidelines were published based on a 2008 re-analysis of the 4th Task Force data that excluded all children with BMIz above the 85th percentile. Since overweight and obese children tend to have higher blood pressures, their exclusion shifts the new BP centiles downward; to compensate, the clinically important thresholds were also revised. For details, see Clinical Practice Guideline for Screening and Management of High Blood Pressure in Children and Adolescents.

The sample.csv file shows the expected variable names and formats. Column order is immaterial, and additional columns are permitted. The variable agemons is age in months, height is in cm, sbp/dbp are measured in mmHg, and sex is coded as M/F. The identifier id should be unique for each observation. Since the CDC LMS tables are tabulated in half-month intervals, age is rounded to the nearest value prior to LMS look-up, which has neglible impact on the calculated BP scores.

A spreadsheet with comma separated variables (.csv) may be created using the 'Save As' .csv option in Excel and uploaded using the sidebar on the left. The R macro will then calculate Z-scores for height, SBP, and DBP. Once results are displayed, download them by clicking the <Download> button, which will typically save them to your Download folder with 'out_' prepended to the original dataset name.

Download Results