raw_GLI: Convert z-scores back to raw spirometric values using GLI-2012 equations

Description

This function takes z-scores based on the GLI-2012 equations, plus demographic data (age, height, gender and ethnicity), and converts them back into absolute spirometry measurements (FEV1, FVC, etc) in lt.

Usage

raw_GLI(
  age,
  height,
  gender = 1,
  ethnicity = 1,
  FEV1 = NULL,
  FVC = NULL,
  FEV1FVC = NULL,
  FEF2575 = NULL,
  FEF75 = NULL,
  FEV075 = NULL,
  FEV075FVC = NULL
)

Value

If only one spirometry z-score argument is supplied, the function returns a numeric vector. If more are supplied, the function returns a data.frame with the same number of columns.

Arguments

age: Age in years
height: Height in meters
gender: Gender (1 = male, 2 = female) or a factor with two levels (first = male). Default is 1.
ethnicity: Ethnicity (1 = Caucasian, 2 = African-American, 3 = NE Asian, 4 = SE Asian, 5 = Other/mixed). Default is 1.
FEV1: Forced Expiratory Volume in 1 second (z-score)
FVC: Forced Vital Capacity (z-score)
FEV1FVC: FEV1 / FVC (as z-score)
FEF2575: Forced Expiratory Flow between 25% and 75% of FVC (z-score)
FEF75: Forced Expiratory Flow at 75% of FVC (z-score)
FEV075: Forced Expiratory Volume in 0.75 sec (z-score)
FEV075FVC: FEV0.75 / FVC (as z-score)

Details

At least one of the spirometric z-score arguments must be set (i.e. be non-NULL). Arguments age, height, gender and ethnicity must be vectors of length equal to the length of the z-score vector(s), or of length one, in which case their value is recycled. If any input vector is not of equal length, the function stops with an error.

Examples

Run this code

# Random data, 4 patients, one z-score parameter supplied (FEV1)
raw_GLI(age=seq(25,40,5), height=c(1.8, 1.9, 1.75, 1.85),
      gender=c(2,1,2,1), FEV1=c(-1.2, -1.9, 0, 0.5))