# 📦 pediatric.zcalc

pediatric.zcalc provides functions to compute individual percentile ranks and z-scores for clinical biomarkers in children, adolescents and young adults, based on age-, sex-, and height-specific reference data from the IDEFICS study and the Biomarkers4Pediatrics collaboration. It also supports the computation of a composite Metabolic Syndrome (MetS) score and associated monitoring/action levels for health monitoring.

🔧 Installation

You can install the development version of pediatric.zcalc from GitHub using:

# Install devtools if not already installed
install.packages("devtools")

# Install directly from GitHub
devtools::install_github("bips-hb/pediatric.zcalc")

🚀 Example

library(pediatric.zcalc)

# Input: data frame with raw values
df <- data.frame(
  sex = c("f", "m"),
  age = c(8, 15),          # years
  height = c(120, 125),    # cm
  waist = c(55, 60),       # cm
  homa = c(1.2, 1.4),      # HOMA-IR, dimensionless
  sbp = c(100, 105),       # mmHg
  dbp = c(65, 70),         # mmHg
  trg = c(80, 90),         # mg/dL
  hdl = c(50, 45),         # mg/dL
  crp = c(6, 2)            # mg/L
)

# Calculate z-scores and MetS
results <- ScoreCalc(df, return_values = c("z.score", "MetS"))

# View output
print(results)

📚 Functions

• get_scores() — Get percentiles or z-scores for a single variable.
• ScoreCalc() — Calculate scores for multiple variables and optionally MetS.
• MetSScore() — Calculate MetS from z-scores.
• action_levels() — Assign action levels based on percentile cutoffs.

📖 Reference

This package uses internal parameter tables based on the IDEFICS study, a European cohort focused on childhood obesity and metabolic health, and Biomarkers4Pediatrics, an international multicohort pediatric biomarker collaboration:

• Ahrens, W., Moreno, L. A., Mårild, S., Molnár, D., Siani, A., De Henauw, S., Böhmann, J., Günther, K., Hadjigeorgiou, C., Iacoviello, L., Lissner, L., Veidebaum, T., Pohlabeln, H. & Pigeot, I. on behalf of the IDEFICS consortium (2014). Metabolic syndrome in young children: definitions and results of the IDEFICS study. International Journal of Obesity, 38 (Suppl 2), S4–S14.

• http://www.biomarkers4pediatrics.eu/

The reference data used for all variables other than CRP in this package were originally published in: - bips-hb/IDEFICS-Score_Calculator — a repository containing the IDEFICS tables and an R script version of the scoring logic.

This package improves upon and packages that logic cleanly for programmatic and research use.