lookup_limits: Lookup Limits in Reference Tables

In zlog: Z(log) Transformation for Laboratory Measurements

Lookup Limits in Reference Tables

Description

Reference limits are specific for age and sex. Each laboratory institute has its own reference limits. This function is useful to query a dataset against this database.

Usage

lookup_limits(age, sex, table)

Arguments

age	numeric, patient age.
sex	character/factor, patient sex, has to be the same length as age.
table	data.frame, reference table, has to have the columns: "age", numeric (same units as in age, e.g. days or years, age of 0 matches all ages), "sex", factor (same levels for male and female as sex and a special level "both"), "lower" and "upper", numeric for the lower and upper reference limits. If an "param" column is given the "lower" and "upper" limits for all different values in "param" is returned. Additional columns are allowed (and ignored).

Value

matrix, with 2 columns ("lower", "upper") and as many rows as length(age).

Author(s)

Sebastian Gibb

Examples

reference <- data.frame(
    param = c("albumin", rep("bilirubin", 4)),
    age = c(0, 1, 2, 3, 7),     # days
    sex = "both",
    units = c("g/l", rep("µmol/l", 4)), # ignored
    lower = c(35, rep(NA, 4)),  # no real reference values
    upper = c(52, 5, 8, 13, 18) # no real reference values
)

# lookup albumin reference values for 18 year old woman
lookup_limits(
    age = 18 * 365.25,
    sex = "female",
    table = reference[reference$param == "albumin",]
)

# lookup albumin and bilirubin values for 18 year old woman
lookup_limits(
    age = 18 * 365.25,
    sex = "female",
    table = reference
)

# lookup bilirubin referenc values for infants
lookup_limits(
    age = 0:8,
    sex = rep(c("female", "male"), 5:4),
    table = reference[reference$param == "bilirubin",]
)

zlog documentation built on Jan. 6, 2023, 1:25 a.m.