A vectorised function to calculate estimated glomerular filtration rate using the abbreviated (four variable) MDRD equation. By default the equation accepts serum creatinine in µmol/l but can be changed to mg/dl by setting the units parameter to "US". To allow for serial measurements over time, such as for transplant follow-up data, there is an optional offset = n parameter which increases the age value used in the equation by n years.
mdrd(creat, age, sex, ethnicity, units = "SI", offset = 0)
numeric vector of serum creatinine in µmol/l (or mg/dl if units = "US")
numeric vector of age in years (accepts integers or decimals)
character vector of sex ("F" for female, "M" for male)
character vector of patient ethnicity, one of "black" or "non-black"
non-vectorised optional parameter for creatinine unit ("SI" for µmol/l (default), "US" for mg/dl)
non-vectorised optional parameter for offset in years
a numeric vector of eGFR values
Reference: Levey AS, Greene T, Kusek JW, et al. A simplified equation to predict glomerular filtration rate from serum creatinine. J Am Soc Nephrol 2000; 11:A0828.
mdrd(creat = 120, age = 45.2, sex = "M", ethnicity = "non-black")#>  60.32037mdrd(creat = 1.5, age = 64.3, sex = "F", ethnicity = "black", units = "US")#>  44.91859