Calculate eGFR or creatinine clearance

Calculate the estimated glomerular filtration rate (eGFR) or estimated creatinine clearance (CrCl), both indicators of renal function, based on measured serum creatinine. Note that CrCl overestimates GFR, because creatinine is also secreted by the renal tubules, so the two are not interchangeable. Regardless of method, the estimate is returned in the value element of the output.

Most equations report values per 1.73 m2 body surface area. The Cockcroft-Gault, Wright, and Jelliffe for unstable renal function equations report absolute values (mL/min) instead. By default, values are returned in the units of the equation; use relative to convert between them.

Methods estimating GFR:

Revised Lund-Malmo (malmo_lund_revised)
Modification of Diet in Renal Disease study (MDRD; mdrd, mdrd_ignore_race, mdrd_original, mdrd_original_ignore_race), with or without consideration of race, using either the original equation (published 2001) or the equation updated to reflect serum creatinine assay standardization (2006)
CKD-EPI (ckd_epi, ckd_epi_ignore_race, ckd_epi_as_2021), with or without consideration of race, or 2021 re-fit without race
European Kidney Function Consortium (EKFC; ekfc). Applicable from 2 years of age.
Schwartz (schwartz)
Schwartz revised / bedside (schwartz_revised, bedside_schwartz)
Wright equation for eGFR in cancer patients (wright), with creatinine measured using the Jaffe assay. Reports absolute values.

Methods estimating CrCl:

Cockcroft-Gault (cockcroft_gault, cockcroft_gault_ideal, cockcroft_gault_adjusted, cockcroft_gault_adaptive), using total, ideal, adjusted, or adaptive (see calc_dosing_weight()) body weight. Reports absolute values.
C-G spinal cord injury (cockcroft_gault_sci), using correction factor of 0.7, representing median correction point reported in the original publication (paraplegic patients: 0.8; tetraplegic patients: 0.6)
Jelliffe (jelliffe). Reports values per 1.73 m2.
Jelliffe for unstable renal function (jelliffe_unstable). Reports absolute values. Note that the 15% reduction in P_adj recommended for hemodialysis patients is not included in this implementation.

Usage

calc_egfr(
  method = c("cockcroft_gault", "cockcroft_gault_ideal", "cockcroft_gault_adjusted",
    "cockcroft_gault_adaptive", "cockcroft_gault_sci", "mdrd", "mdrd_ignore_race",
    "mdrd_original", "mdrd_original_ignore_race", "ckd_epi", "ckd_epi_ignore_race",
    "ckd_epi_as_2021", "ekfc", "malmo_lund_revised", "schwartz", "schwartz_revised",
    "bedside_schwartz", "jelliffe", "jelliffe_unstable", "wright"),
  sex = NULL,
  age = NULL,
  scr = NULL,
  scr_unit = NULL,
  race = "other",
  weight = NULL,
  height = NULL,
  bsa = NULL,
  preterm = FALSE,
  ckd = FALSE,
  times = NULL,
  bsa_method = "dubois",
  relative = NULL,
  unit_out = "mL/min",
  verbose = TRUE,
  min_value = NULL,
  max_value = NULL,
  fail = TRUE,
  ...
)

Arguments

method: eGFR or CrCl estimation method, choose from "cockcroft_gault", "cockcroft_gault_ideal", "cockcroft_gault_adjusted", "cockcroft_gault_adaptive", "cockcroft_gault_sci", "mdrd", "mdrd_ignore_race", "mdrd_original", "mdrd_original_ignore_race", "ckd_epi", "ckd_epi_ignore_race", "ckd_epi_as_2021", "ekfc", "malmo_lund_revised", "schwartz", "schwartz_revised", "bedside_schwartz", "jelliffe", "jelliffe_unstable", "wright". Defaults to "cockcroft_gault".
sex: sex
age: age, in years
scr: serum creatinine (mg/dL)
scr_unit: "mg/dL" or "micromol/L" (=="umol/L")
race: "black" or "other", Required for CKD-EPI and MDRD methods for estimating GFR. To use these methods without race, use method = "ckd_epi_ignore_race", method = "ckd_epi_as_2021", method = "mdrd_ignore_race" or method = "mdrd_original_ignore_race". See Note section below for important considerations when using race as a predictive factor in eGFR.
weight: weight, in kg
height: height, in cm, used for converting to/from BSA-normalized units.
bsa: body surface area
preterm: is patient preterm? Used for Schwartz method.
ckd: chronic kidney disease? Used for Schwartz method.
times: vector of sampling times (in days!) for creatinine (only used in Jelliffe equation for unstable patients)
bsa_method: BSA estimation method, see calc_bsa() for details
relative: TRUE/FALSE. Report eGFR as per 1.73 m2? Requires BSA if conversion is required. If NULL (default), uses the units of the equation: FALSE for the Cockcroft-Gault, Wright, and Jelliffe for unstable renal function equations, and TRUE for the others.
unit_out: "mL/min" (default), "mL/hr", "L/min", or "L/hr" (case-insensitive)
verbose: verbosity, show guidance and warnings. TRUE by default
min_value: minimum value (NULL by default). The cap is applied in the same unit as the unit_out.
max_value: maximum value (NULL by default). The cap is applied in the same unit as the unit_out.
fail: invoke stop() if not all covariates available?
...: arguments passed on to calc_abw() or calc_dosing_weight()

Note

The MDRD and CKD-EPI equations use race as a factor in estimation of GFR. Racism has historically been and continues to be a problem in medicine, with racialized patients experiencing poorer outcomes. Given this context, the use of race in clinical algorithms should be considered carefully (Vyas et al., NEJM (2020)). Provided here are versions of the CKD-EPI and MDRD equations that do not consider the race of the patient. Removing race from GFR estimation may lead to worse outcomes for Black patients in some contexts (Casal et al., The Lancet (2021)). On the other hand, including race in GFR estimation may also prevent Black patients from obtaining procedures like kidney transplants (Zelnick, et al. JAMA Netw Open. (2021)). In 2021, the NKF/ASN Task Force on Reassessing the Inclusion of Race in Diagnosing Kidney Diseases published revised versions of the CKD-EPI equations refit on the original data but with race excluded, which may produce less biased estimates (Inker, et al., NEJM (2021)).

References

Cockcroft-Gault: Cockcroft & Gault, Nephron (1976)
Cockcroft-Gault for spinal cord injury: Mirahmadi et al., Paraplegia (1983)
Revised Lund-Malmo: Nyman et al., Clinical Chemistry and Laboratory Medicine (2014)
MDRD: Manjunath et al., Curr. Opin. Nephrol. Hypertens. (2001) and Levey et al., Clinical Chemistry (2007). (See Note.)
CKD-EPI: Levey et al., Annals of Internal Medicine (2009). (See Note.)
CKD-EPI (2021): Inker, et al., NEJM (2021).
EKFC: Pottel et al., Annals of Internal Medicine (2021)
Schwartz: Schwartz et al., Pediatrics (1976)
Schwartz revised / bedside: Schwartz et al., Journal of the American Society of Nephrology (2009)
Jelliffe: Jelliffe, Annals of Internal Medicine (1973)
Jelliffe for unstable renal function: Jelliffe, American Journal of Nephrology (2002)
Wright: Wright et al., British Journal of Cancer (2001)

Examples