zscore_NHANES3: Convert spirometric values to z-scores using NHANES III...

In rspiro: Implementation of Spirometry Equations

Convert spirometric values to z-scores using NHANES III equations

Description

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

Usage

zscore_NHANES3(
  age,
  height,
  gender = 1,
  ethnicity = 1,
  FEV1 = NULL,
  FVC = NULL,
  FEV1FVC = NULL,
  PEF = NULL,
  FEF2575 = NULL,
  FEV6 = NULL,
  FEV1FEV6 = NULL
)

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 = Mexican-American). Default is 1.
FEV1	Forced Expiratory Volume in 1 second (lt)
FVC	Forced Vital Capacity (lt)
FEV1FVC	FEV1 / FVC ratio
PEF	Peak Expiratory Flow (lt)
FEF2575	Forced Expiratory Flow between 25% and 75% of FVC (lt/s)
FEV6	Forced Expiratory Volume in 6 seconds (lt)
FEV1FEV6	FEV1 / FEV6 ratio

Details

At least one of the spirometric measurement 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 spirometric measurement 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.

Normal distributions are assumed for all parameters, even though per the NHANES III equations paper (Hankinson et al) this was observed only for FEV1, FVC, PEF and FEV6.

Value

If only one spirometry 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.

Examples

# Random data, 4 patients, one parameter supplied (FEV1)
zscore_NHANES3(age=seq(25,40,4), height=c(1.8, 1.9, 1.75, 1.85),
      gender=c(2,1,2,1), ethnicity=rep(1,4), FEV1=c(3.5, 4, 3.6, 3.9))

rspiro documentation built on Aug. 7, 2023, 5:06 p.m.