This R Shiny application calculates SBP and DBP percentiles for children aged 2-18 years based on the 2017 AAP Clinical Practice Guidelines 2017 AAP Clinical Practice Guidelines, Flynn et al, 2017. For details, see our batch file calculator for data in spreadsheet format.
Unlike the batch (spreadsheet) calculator, clinic data are added directly in the form below. Dates must be entered using the format
and are stored as days since Jan 1, 1970; they can be entered directly or using the calendar tool. Height is in cm, weight in kilograms, and BP in mmHg (auscultation). After entering your selections, click
Input data are displayed by clicking
. To process, click
BP measurements are rounded to the nearest whole number before calculating percentiles. Dr. Rosner's algorithm does not assign BP percentiles for outlier heights i.e. HtZ < -3.09 (0.1%) or HtZ > 3.09 (99.9%), which are flagged by setting 'outler' = 1.The output also contains the variable 'stage', which assigns a diagnosis of normal, elevated, stage 1, or stage 2 based on the 2017 AAP guidelines, which represent a mixture of percentiles and static thresholds.
We also return sex-, age-, and height-specific 90th percentile values for SBP (fxsys) and DBP (fxdia). Users should exercise caution and confirm important results using published charts, particularly for assignment of BP stages. For example, a small number of children < 13y will be normal with BP < 90th percentile, but have high BP because they exceed absolute thresholds (> 120/80). This should not be confused with another statistical issue inherent in quantile regression, which was described by the WHO Expert Panel (Borghi, 2006): Since each centile is fitted separately without additional constraints, centile curves may actually cross, and it is theoretically possible for the 90th percentile to be less than the 85th! While we have yet to find an example of 'crossed percentiles', we have seen cases where the 87th and 90th percentiles are equal, which may lead to a diagnosis of elevated blood pressure even though the assigned percentile is less than the 90th. As recommended by the AAP subcommittee, we generally apply the 'lesser of' condition when dealing with ambiguity. NB: Percentile calculations are only valid between 2-18y of age. To be consistent with the AAP tables, this calculator will in fact return percentiles for children as young as 1y. However, these results are based on measurements from a small number of children < 2y of age (Table 1, Rosner 2008). Caveat Emptor.