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Journal of Nephrology (2020) 33:639–648 https://doi.org/10.1007/s40620-020-00773-6
EDITORIAL
Nomenclature for kidney function and disease: executive summary and glossary from a Kidney Disease: Improving Global Outcomes (KDIGO) consensus conference
Andrew S. Levey1 · Kai‑Uwe Eckardt2 · Nijsje M. Dorman3 · Stacy L. Christiansen4 · Michael Cheung5 · Michel Jadoul6 · Wolfgang C. Winkelmayer7
Published online: 16 July 2020 © KDIGO 2020
A primary obligation of medical journals is the responsible, professional, and expeditious delivery of knowledge from researchers and practitioners to the wider community [1]. The task of journal editors, therefore, rests not merely in selecting what to publish, but in large measure judging how it can best be communicated. The challenge of improving descriptions of kidney function and disease in medical pub-lishing was the impetus for a Kidney Disease: Improving Global Outcomes (KDIGO) Consensus Conference held in June 2019. The conference goals included standardizing and refining kidney-related nomenclature used in English-language scientific articles and developing a glossary that can be used by journals [2].
The rationale for the conference was that the world-wide burden of kidney disease is rising, but public aware-ness remains limited, underscoring the need for effective
communication by stakeholders in the kidney health com-munity [3–6]. Despite this need, the nomenclature for describing kidney function and disease lacks uniformity and clarity. Two decades ago, a survey of hundreds of pub-lished articles and meeting abstracts reported a broad array of overlapping, confusing terms for chronic kidney disease (CKD) and advocated adoption of unambiguous terminology [7]. Nevertheless, terms flagged by that analysis as prob-lematic, such as “chronic renal failure” and “pre-dialysis,” still appear in current-day publications. A coherent, shared nomenclature could improve communication at all levels, to not only foster better appreciation of the burden of disease but also aid understanding of how patients feel about their disease, allow more effective communication between kid-ney disease specialists and other clinicians, advance more straightforward comparison and integration of datasets, enable better recognition of gaps in knowledge for future research, and facilitate more comprehensive public health policies for acute and chronic kidney disease.
Developing consistent, patient-centered, and precise descriptions of kidney function and disease in the scientific literature is an important objective to align communication in clinical practice, research, and public health. Although some terms have been in use for decades, the increased exchange of information among stakeholders makes it timely to revisit nomenclature in order to ensure consistency. The
This article is being published in Kidney International Reports and reprinted concurrently in several journals. The articles cover identical concepts and wording but vary in minor stylistic and spelling changes, detail, and length of manuscript, in keeping with each journal’s style. Any of these versions may be used in citing this article. Excerpts are adapted with permission of KDIGO and the International Society of Nephrology.
Electronic supplementary material The online version of this article (https ://doi.org/10.1007/s4062 0-020-00773 -6) contains supplementary material, which is available to authorized users.
* Andrew S. Levey [email protected]
* Kai-Uwe Eckardt [email protected]
1 Division of Nephrology, Tufts Medical Center, 850 Washington Street, Box 391, Boston, MA 02111, USA
2 Department of Nephrology and Medical Intensive Care, Charité—Universitätsmedizin Berlin, Augustenburger Platz 1, 13353 Berlin, Germany
3 American Journal of Kidney Diseases, Philadelphia, USA4 Journal of the American Medical Association, Chicago, USA5 Kidney Disease: Improving Global Outcomes (KDIGO),
Brussels, Belgium6 Cliniques Universitaires Saint Luc, Université Catholique de
Louvain, Brussels, Belgium7 Selzman Institute for Kidney Health, Section of Nephrology,
Department of Medicine, Baylor College of Medicine, Houston, TX, USA
640 Journal of Nephrology (2020) 33:639–648
1 3
goal is to facilitate communication within and across disci-plines and between practitioners and patients, with the ulti-mate hope of improving outcomes through consistency and precision.
Attendees at the conference included editors of kidney subspecialty journals, kidney subspecialty editors at gen-eral medical journals and journals from other subspecialties, experienced authors of clinical kidney health research, and patients. Guiding principles of the conference were that the revised nomenclature should be patient-centered, precise, and consistent with nomenclature used in the KDIGO guide-lines. The discussion focused on general description of acute and chronic kidney disease and kidney measures, rather than specific kidney diseases and particular measures of function and structure. Classifications of causes of kidney disease and procedures, performance measures, and outcome met-rics for dialysis and transplantation were considered beyond the scope of discussion.
As described in detail in the conference report [8] the meeting attendees reached general consensus on the fol-lowing recommendations: (1) to use “kidney” rather than “renal” or “nephro-” when referring to kidney disease and kidney function; (2) to use “kidney failure” with appropri-ate descriptions of presence or absence of symptoms, signs, and treatment rather than “end-stage kidney disease”; (3) to use the KDIGO definition and classification of acute kidney diseases and disorders (AKD) and acute kidney injury (AKI) rather than alternative descriptions to define and classify the severity of these; (4) to use the KDIGO definition and classification of CKD rather than alternative descriptions to define and classify it; and (5) to use specific kidney meas-ures, such as albuminuria or decreased glomerular filtra-tion rate, rather than “abnormal” or “reduced” kidney func-tion to describe alterations in kidney structure and function (Table 1). Accordingly, the proposed glossary contains five corresponding sections, and comprises specific items for which there was general agreement among the conference participants (https ://kdigo .org/confe rence s/nomen clatu re/; Table 2) [8]. For each section, the glossary includes pre-ferred terms, abbreviations, descriptions, and terms to avoid, with the acknowledgment that journals may choose which of the recommendations to implement, and that journal style will dictate when and how to abbreviate terms to be consist-ent with nomenclature for other diseases.
A guiding principle for the development of the glossary was patient-centeredness. The Health and Medicine Divi-sion of the US National Academies of Sciences defines patient-centered care as “[p]roviding care that is respectful of, and responsive to, individual patient preferences, needs and values, and ensuring that patient values guide all clini-cal decisions.”[9] One of the 10 general principles recom-mended for redesign of the health system is: “Knowledge is shared and information flows freely. Patients should have
unfettered access to their own medical information and to clinical knowledge. Clinicians and patients should commu-nicate effectively and share information.” In principle, the terms used to describe kidney function and disease should be understandable to all, with acknowledgment of variation in the level of health literacy. Use of multiple terms with similar meaning can lead to confusion, as can use of terms that forecast the future (such as “pre-dialysis”) rather than describe the present. However, convergence of multiple names into an accepted set of terms does require that users of the glossary are willing to accept that labels that have been preeminent historically, and that may be more familiar or memorable even now, should now be superseded [10].
Of equal importance to patient-centeredness in the devel-opment of the glossary was precision, which can generally be defined as exactness or accuracy [10]. How medicine is defined and understood is changing rapidly from a descrip-tive, disease-based categorization in which multiple patho-genetic pathways may be conflated to a mechanism-based categorization that will promote more precise management of clinical problems. The latter approach, in which a molecu-lar profile is added to the clinical and morphologic profile, has already revolutionized diagnosis and treatment in oncol-ogy. In nephrology, the ongoing Kidney Precision Medicine Project, funded by the National Institutes of Health, seeks to ethically obtain and evaluate kidney biopsies from par-ticipants with AKI or CKD; create a kidney tissue atlas; define disease subgroups; and identify cells, pathways, and targets for novel therapies [11]. As has occurred in oncol-ogy, it is anticipated that refinements that result in more precise disease descriptions will be incorporated into current nomenclature for kidney function and disease, rather than replace it altogether. Thus, although the glossary is designed to be consistent with current knowledge and stable enough to remain relevant for the foreseeable future, it is also intended to be sufficiently flexible to accommodate new vocabulary arising with advances in the field.
A central strength of the proposed glossary is that it is based on existing KDIGO definitions, classifications, and nomenclature for acute and chronic kidney disease. In addi-tion, it was developed using the following: a systematic process, including articulation of a clear and transparent rationale (patient-centeredness and precision); capture of stakeholder viewpoints via patient focus groups [12] and a corresponding survey; a period of public comment on con-ference scope; and attainment of consensus among attendees at the conference. Although the recommendations are not likely to answer all concerns, the consensus among confer-ence attendees was that standardizing scientific nomencla-ture is a necessary first step to improving communications among clinicians, researchers, and public health officials, and with patients, their families and caregivers, and the public.
641Journal of Nephrology (2020) 33:639–648
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Limitations of the proposed glossary are that it is restricted to English (nuances may be difficult to trans-late); only a limited number of stakeholders were able to
participate, owing to practical reasons; it is not compre-hensive (it does not include disease classification, dialysis, transplantation); and further specification is required for
Table 1 Key takeaways from the conference
ACR, albumin-creatinine ratio; AER, albumin excretion rate; AKD, acute kidney diseases and disorders; AKI, acute kidney injury; CKD, chronic kidney disease; CKD-EPI, CKD Epidemiology Collaboration; eGFR, estimated glomerular filtration rate; eGFRcr, estimated glomerular filtration rate derived from creatinine; eGFRcr-cys, estimated glomerular filtration rate derived from creatinine and cystatin C; eGFRcys, estimated glomerular filtration rate derived from cystatin C; ESKD, end-stage kidney disease; ESRD, end-stage renal disease; GFR, glomerular filtration rate; KDIGO, Kidney Disease: Improving Global Outcomes; KRT, kidney replacement therapy; MDRD, Modification of Diet in Renal Disease; mGFR, measured glomerular filtration rate; NIDDK, National Institute of Diabetes and Digestive and Kidney Diseases; PCR, protein-creatinine ratio; PER, protein excretion rate; RRT, renal replacement therapy; US, United States
Use the term “kidney” rather than “renal” to describe kidney function and kidney disease. In English, the terms renal and kidney are still used interchangeably, resulting in different acronyms describing the same condition or status (e.g., ESRD/ESKD and RRT/KRT). It is more likely that patients and the public would understand the terms incorporating the more familiar noun “kidney,” rather than the less familiar adjective “renal,” which is derived from Latin and is labeled as technical in some dictionaries. Although writing guides may generally favor using an appropriate adjective over a noun as a modifier, there are high-profile precedents for the use of kidney as a modifier, such as AKI, CKD, and NIDDK (National Institute of Diabetes and Digestive and Kidney Diseases)
Avoid the term “end-stage.” Although rooted in US law, the term is not patient sensitive, may connote a stigma, and may discourage advocacy. In the US, ESRD (ESKD) is a synonym for receipt of KRT. However, KRT is a treatment rather than a disease. The term “kidney failure,” which is defined as GFR < 15 ml/min per 1.73 m2 or treatment by dialysis, is as comprehensive as “ESRD/ESKD,” without suffering from its limitations
Improve characterization of the full spectrum of kidney failure. Although all patients with kidney failure have GFR < 15 ml/min per 1.73 m2 or are undergoing treatment by dialysis, the severity of symptoms varies greatly. We lack terms to describe the severity of symptoms and signs, and yet they are indications for initiating KRT. There are also no common patient-reported outcome measures to describe severity. The term “kidney failure” in a chronic setting is defined as > 3 months, whereas in an acute setting (i.e., AKI stage 3), it is reserved for a duration of ≤ 3 months. Kidney failure could be further classified according to patient-reported outcomes (symptoms)
Use more-descriptive terms for treatments for kidney failure. Many patients with kidney failure do not undergo KRT. The terms “treated” vs. “untreated” have been used, but this is not consistent with the idea that supportive care is indeed treatment. Furthermore, in some cases, patients choose supportive care rather than KRT; in other cases, they do not have a choice because of lack of insurance or lack of availability. Finally, some patients may not be under the care of a physician at all
Avoid the use of “chronic kidney disease (CKD)” as a synonym for “GFR < 60 ml/min per 1.73 m2.” CKD includes markers of kidney damage or GFR < 60 ml/min per 1.73 m2 for > 3 months, so ascertainment of GFR without assessment for markers of kidney damage is insufficient for classification of CKD status when GFR > 60 ml/min per 1.73 m2. If chronicity is not documented, it can be inferred on the basis of corrobora-tive clinical data or presumed in the absence of clinical data to the contrary
Avoid the use of “acute kidney injury (AKI)” as a synonym for “acute kidney diseases and disorders (AKD).” AKD refers to kidney diseases and disorders with a duration of ≤ 3 months, whereas AKI refers to kidney diseases and disorders with onset within 1 week
Use “CKD GFR and albuminuria categories” and “AKI stages” to describe disease severity, rather than employing ill-defined terms such as “mild,” “moderate,” “severe,” and “advanced”
Use the terms “GFR categories” and “albuminuria categories” rather than “CKD stages” when describing the level of GFR and albuminuria in populations either without CKD or without ascertainment of both GFR and albuminuria
Use the term “risk categories” to describe combinations of the G (GFR) and A (albuminuria) categories from the KDIGO heat map (see Sup-plementary Figure S1)
Use specific terms, such as “GFR,” “tubular secretion,” “tubular reabsorption,” “albuminuria,” and “proteinuria,” rather than general terms, such as “abnormal” or “reduced” kidney function, damage, or injury, when possible. Because kidney function comprises several functional catego-ries, including excretory, endocrine, and metabolic functions, it should be described as specifically as possible. GFR is closely linked with the excretory function, but it should not be used as a synonym, because tubular reabsorption and excretion also contribute to excretory function
When referring to “decreased or decreasing GFR,” avoid the use of different, poorly defined terms such as “impaired kidney function,” “renal insufficiency,” “renal dysfunction,” “renal impairment,” “worsening kidney function,” and “kidney function decline”
When referring to GFR, use descriptive abbreviations (mGFR for measured GFR and eGFR for estimated GFR, with specific notation based on the endogenous filtration markers used (e.g., eGFRcr, eGFRcys, and eGFRcr-cys). Additional detail can be given in the methods. For mGFR, the methods should describe the exogenous filtration marker (e.g., inulin, iothalamate, iohexol) and clearance method (urinary clearance, plasma clearance). For eGFR, the methods should describe the estimating equation used (CKD-EPI; MDRD Study)
Avoid referring to “albuminuria” or “proteinuria” as “decreased kidney function.” Albuminuria and proteinuria are markers of kidney damage, rather than measures of kidney function
When referring to albuminuria or proteinuria, avoid the terms “microalbuminuria” and “macroalbuminuria/clinical proteinuria.” Use the terms “moderately increased” or “severely increased” instead
When referring to albuminuria and proteinuria, use descriptive abbreviations, such as “urine albumin or protein excretion rates (AER and PER)” and “urine albumin–creatinine or protein–creatinine ratios (ACR and PCR)”
642 Journal of Nephrology (2020) 33:639–648
1 3
Tabl
e 2
KD
IGO
Kid
ney
Func
tion
and
Dis
ease
Glo
ssar
y: su
gges
ted
term
s to
desc
ribe
kidn
ey fu
nctio
n an
d ki
dney
dis
ease
, and
crit
eria
and
mea
sure
s defi
ning
them
Pref
erre
d te
rmSu
gges
ted
abbr
evia
tions
aR
atio
nale
/exp
lana
tion
Term
s to
avoi
d
Part
1. K
idne
y fu
nctio
n an
d di
seas
eTh
e te
rm “
kidn
ey”
shou
ld b
e us
ed p
refe
rent
ially
whe
n de
scrib
ing
kidn
ey d
isea
se a
nd k
idne
y fu
nctio
n, w
ith e
xcep
tions
“Ren
al,”
the
prefi
x “n
ephr
o-”
(exc
ept i
n th
e se
t-tin
g of
spec
ific
func
tions
, dis
ease
s, or
syn-
drom
es; s
ee b
elow
)K
idne
y di
seas
eRe
nal d
isea
se, n
ephr
opat
hy (e
xcep
t in
the
set-
ting
of sp
ecifi
c di
seas
es, e
.g.,
mem
bran
ous
neph
ropa
thy)
Kid
ney
func
tion
Refle
cts t
he e
ntire
ty o
f diff
eren
t and
com
plex
phy
siol
ogic
al fu
nctio
ns o
f the
kid
ney;
shou
ld n
ot
be e
quat
ed w
ith g
lom
erul
ar fi
ltrat
ion
rate
(GFR
) onl
yRe
nal f
unct
ion
(exc
ept w
hen
desc
ribin
g sp
ecifi
c fu
nctio
ns, e
.g.,
rena
l aci
dific
atio
n, re
nal c
once
n-tra
ting
mec
hani
sm)
Gen
eral
term
app
licab
le to
var
ious
asp
ects
of k
idne
y fu
nctio
n th
at sh
ould
be
spec
ified
-tio
nG
ener
al te
rm a
pplic
able
to v
ario
us a
spec
ts o
f kid
ney
func
tion
that
shou
ld b
e sp
ecifi
edRe
nal/k
idne
y im
pairm
ent,
insu
ffici
ency
, dys
func
-tio
n; a
zote
mia
-tio
nR
KF
Kid
ney
func
tion
in p
eopl
e w
ith k
idne
y fa
ilure
rece
ivin
g K
RT; f
urth
er sp
ecifi
catio
n is
requ
ired,
e.
g., u
rine
flow
rate
, sol
ute
clea
ranc
e. A
lthou
gh it
is u
sual
ly u
sed
in th
e se
tting
of d
ialy
sis,
this
term
cou
ld b
e us
ed to
refe
r to
nativ
e ki
dney
func
tion
in k
idne
y tra
nspl
ant r
ecip
ient
s
Resi
dual
rena
l fun
ctio
n (R
RF)
Kid
ney
stru
ctur
eRe
nal s
truct
ure
(exc
ept w
hen
desc
ribin
g sp
ecifi
c str
uctu
res w
ithin
the
kidn
ey, s
uch
as a
rtery
, ve
in, c
apsu
le, p
aren
chym
a, c
orte
x, m
edul
la,
glom
erul
i, tu
bule
s, in
ters
titiu
m, c
ysts
, tum
ors)
Gen
eral
term
app
licab
le to
var
ious
asp
ects
of k
idne
y str
uctu
re th
at sh
ould
be
spec
ified
struc
ture
Gen
eral
term
app
licab
le to
var
ious
asp
ects
of k
idne
y str
uctu
re th
at sh
ould
be
spec
ified
Cau
ses o
f kid
ney
dise
ase
Cau
se o
f AK
I, A
KD
, and
CK
D sh
ould
be
indi
cate
d w
hene
ver p
ossi
ble.
Cau
se m
ay b
e kn
own,
-fie
d
Cau
se sh
ould
not
be
infe
rred
onl
y fr
om p
rese
nce
of c
omor
bid
cond
ition
(suc
h as
dia
bete
s)
Part
2. K
idne
y Fa
ilure
GFR
<
m2 o
r tre
atm
ent b
y di
alys
is; f
urth
er sp
ecifi
catio
n is
requ
ired;
see
belo
wRe
nal f
ailu
re (R
F); e
nd-s
tage
rena
l dis
ease
(E
SRD
); en
d-st
age
kidn
ey d
isea
se (E
SKD
); re
nal d
isea
se; n
ephr
opat
hy; r
enal
/kid
ney
impa
ir-m
ent,
insu
ffici
ency
, dys
func
tion;
azo
tem
iaD
urat
ion
Spec
ifica
tion
pref
erre
d
stag
e 3b
AK
I sta
ge 3
Dis
ease
dur
atio
n ≤
Acu
te re
nal f
ailu
re; r
enal
dis
ease
; nep
hrop
athy
; re
nal/k
idne
y im
pairm
ent,
insu
ffici
ency
, dys
func
-tio
n; a
zote
mia
; ure
mia
KF
Dis
ease
dur
atio
n >
Chr
onic
rena
l fai
lure
; chr
onic
rena
l dis
ease
; ch
roni
c ne
phro
path
y; c
hron
ic re
nal/k
idne
y im
pairm
ent,
insu
ffici
ency
, dys
func
tion;
az
otem
ia; u
rem
ia; i
rrev
ersi
ble
kidn
ey fa
ilure
643Journal of Nephrology (2020) 33:639–648
1 3
Tabl
e 2
(con
tinue
d)
Pref
erre
d te
rmSu
gges
ted
abbr
evia
tions
aR
atio
nale
/exp
lana
tion
Term
s to
avoi
d
Sym
ptom
s and
sign
s -dr
ome
A sy
ndro
me
cons
istin
g of
sym
ptom
s and
sign
s ass
ocia
ted
with
kid
ney
failu
re (d
oes n
ot in
di-
cate
a c
ausa
l rol
e fo
r ure
a)Tr
eatm
ent
Spec
ifica
tion
requ
ired
ther
apyc
KRT
Furth
er sp
ecifi
catio
n is
requ
ired;
incl
udes
dia
lysi
s and
tran
spla
ntat
ion
Rena
l rep
lace
men
t the
rapy
(RRT
)
AK
I sta
ge 3
DA
KI s
tage
3 tr
eate
d by
dia
lysi
sA
KI-
D, d
ialy
sis-
depe
nden
t AK
IC
KD
G5D
CK
D G
5 tre
ated
by
dial
ysis
ESK
D, E
SKF,
ESR
D, E
SRF,
dia
lysi
s-de
pend
ent
CKD
mai
nten
ance
dia
lysi
s; sh
ort-t
erm
refe
rs to
dia
lysi
s for
AK
DC
hron
ic d
ialy
sis,
acut
e di
alys
is (t
he te
rms a
cute
an
d ch
roni
c re
fer t
o du
ratio
n of
kid
ney
dise
ase
rath
er th
an d
urat
ion
of d
ialy
sis t
reat
men
t)-
quen
cyM
odal
ities
•Hem
odia
lysi
s (H
D)
•Hem
ofiltr
atio
n (H
F)•H
emod
iafil
tratio
n (H
DF)
•Per
itone
al d
ialy
sis (
PD, a
mbu
lato
ry o
r aut
omat
ed)
Freq
uenc
y•C
ontin
uous
•Int
erm
itten
t (sh
ort o
r pro
long
ed)
CK
D G
1T–G
5TC
KD
G1–
G5
afte
r tra
nspl
anta
tion
ESK
D, E
SKF,
ESR
D, E
SRF
Spec
ify li
ving
don
or k
idne
y tra
nspl
ant/t
rans
plan
tatio
n (L
DK
T) o
r dec
ease
d do
nor
kidn
ey tr
ansp
lant
/tran
spla
ntat
ion
(DD
KT)
repl
acem
ent t
hera
pyK
FRT
CK
D G
5 tre
ated
by
dial
ysis
or C
KD
G1–
G5
afte
r tra
nspl
anta
tion;
for e
pide
mio
logi
c st
udie
s, bo
th sh
ould
be
incl
uded
ESK
D, E
SKF,
ESR
D, E
SRF
repl
acem
ent t
hera
pyC
KD
G5
with
-ou
t KRT
ESK
D, E
SKF,
ESR
D, E
SRF,
unt
reat
ed k
idne
y fa
ilure
cons
erva
tive
care
Furth
er sp
ecifi
catio
n is
pre
ferr
ed; d
efini
tion
is e
volv
ing
-si
ve c
onse
rvat
ive
care
Furth
er sp
ecifi
catio
n is
pre
ferr
ed: s
peci
fy w
heth
er c
ompr
ehen
sive
cons
erva
tive
care
Part
3. A
cute
kid
ney
dise
ases
and
diso
rder
s (A
KD
) and
acu
te k
id-
ney
inju
ry (A
KI)
Dis
ease
dur
atio
n≤A
cute
rena
l fai
lure
(AR
F); a
cute
rena
l ins
uffi-
cien
cy (A
RI)
Acut
e kid
ney
dise
ases
AK
Dc
KD
IGO
defi
nitio
n: A
KI,
or G
FR<
m2 , o
r mar
kers
of k
idne
y da
mag
e fo
r≤≥
35%
or i
ncre
ase
in S
Cr b
y>50
% fo
r≤A
RF,
AR
I
644 Journal of Nephrology (2020) 33:639–648
1 3
Tabl
e 2
(con
tinue
d)
Pref
erre
d te
rmSu
gges
ted
abbr
evia
tions
aR
atio
nale
/exp
lana
tion
Term
s to
avoi
d
Acut
e kid
ney
inju
ryA
KI
KD
IGO
defi
nitio
n (A
KI i
s a su
bcat
egor
y of
AK
D):
olig
uria
for >
>
>
A
RF,
AR
I
AK
I cla
ssifi
catio
nK
DIG
O c
lass
ifica
tion
by c
ause
and
stag
e pr
efer
red
rath
er th
an st
age
alon
e; e
.g.,
a pa
tient
with
A
KI s
tage
3 d
ue to
ATN
; cla
ssifi
catio
n ap
plie
s to
all A
KI s
tage
sPr
evio
us c
lass
ifica
tions
, inc
ludi
ng R
IFLE
and
A
KIN
(the
KD
IGO
cla
ssifi
catio
n ha
rmon
ized
th
ese
prio
r defi
nitio
ns)
AK
I sta
ges
KD
IGO
defi
nitio
n (a
pplic
able
onl
y to
peo
ple
with
AK
I)A
KI s
tage
1Se
rum
cre
atin
ine
and/
or u
rine
outp
ut c
riter
iaA
KI s
tage
2Se
rum
cre
atin
ine
and/
or u
rine
outp
ut c
riter
iaA
KI s
tage
3Se
rum
cre
atin
ine
and/
or u
rine
outp
ut c
riter
ia
Part
4. C
hron
ic k
idne
y
dise
ase (
CK
D)
Dis
ease
dur
atio
n >
Chr
onic
rena
l fai
lure
(CR
F); E
SRD
; ren
al/k
idne
y im
pairm
ent,
insu
ffici
ency
, dys
func
tion
CK
DK
DIG
O d
efini
tion:
GFR
<
2 or m
arke
rs o
f kid
ney
dam
age
for >
C
RF;
ESR
D; r
enal
/kid
ney
impa
irmen
t, in
suffi
-ci
ency
, dys
func
tion
CK
D cl
assifi
catio
nK
DIG
O C
GA
cla
ssifi
catio
n by
cau
se, G
FR c
ateg
ory
(G1–
G5)
, and
alb
umin
uria
cat
egor
y (A
1–A
3); s
ee b
elow
for d
efini
tions
of G
and
A c
ateg
orie
s. Fo
r exa
mpl
e, a
pat
ient
with
CK
D
G1,
A3
due
to d
iabe
tes,
or a
coh
ort w
ith C
KD
G4–
G5,
A1–
A3
of a
ny c
ause
. Not
e th
at C
KD
cl
assi
ficat
ion
is o
nly
appl
icab
le to
peo
ple
with
CK
D, s
o a
patie
nt c
ould
not
be
clas
sifie
d as
“C
KD
G2,
A1”
if th
ere
was
no
othe
r evi
denc
e of
kid
ney
dam
age
Mild
, mod
erat
e, se
vere
, ear
ly, a
dvan
ced
CK
D;
CK
D st
age
1–5
(com
plet
e de
scrip
tion
pref
erre
d ra
ther
than
G c
ateg
ory
alon
e)
CK
D w
ithou
t K
RTC
KD
G1–
G5,
A1–
A3
of a
ny c
ause
, not
rece
ivin
g di
alys
is o
r tra
nspl
anta
tion
ND
-CK
D (n
on-d
ialy
sis C
KD
), N
DD
-CK
D (n
on–
dial
ysis
-dep
ende
nt C
KD
), pr
edia
lysi
s CK
D,
pre-
ESR
D C
KD
CK
D ri
sk ca
tego
ries
KD
IGO
defi
nitio
ns (c
olor
s ref
er to
hea
t map
in S
uppl
emen
tary
Fig
ure
S1) u
nles
s oth
erw
ise
defin
ed; r
isk
depe
nds o
n th
e ou
tcom
e be
ing
cons
ider
edM
ild, m
oder
ate,
seve
re, e
arly
, adv
ance
d C
KD
low
Low
risk
Refe
rs to
G1A
1, G
2A1
(gre
en)
mod
erat
ely
high
Mod
erat
e ris
kRe
fers
to G
1A2,
G2A
2, G
3aA
1 (y
ello
w)
high
Hig
h ris
kRe
fers
to G
1A3,
G2A
3, G
3aA
2, G
3bA
1 (o
rang
e)
very
hig
hVe
ry h
igh
risk
Refe
rs to
G3a
A3,
G3b
A2,
G3b
A3,
G4A
1, G
4A2,
G4A
3, G
5A1,
G5A
2, G
5A3
(red
)
CK
D p
rogr
essio
nRe
fers
to w
orse
ning
GFR
or a
lbum
inur
ia. O
ther
bio
mar
kers
not
incl
uded
. The
re is
not
yet
co
nsen
sus o
n us
e of
spec
ific
term
s to
desc
ribe
the
timin
g (e
.g.,
early
, lat
e) o
r rat
e (fa
st, s
low
) of
pro
gres
sion
. Use
of s
peci
fic te
rms s
houl
d be
defi
ned
in m
etho
dsFu
rther
spec
ifica
tion
may
be
requ
ired:
GFR
dec
line
may
occ
ur d
urin
g th
erap
y fo
r oth
er c
ondi
-tio
ns, w
hich
may
not
be
cons
ider
ed a
s CK
D p
rogr
essi
onC
KD
rem
issio
nRe
fers
to im
prov
ing
GFR
or a
lbum
inur
ia. C
riter
ia d
epen
d on
dis
ease
. Use
of s
peci
fic te
rms
shou
ld b
e de
fined
in m
etho
ds
645Journal of Nephrology (2020) 33:639–648
1 3
Tabl
e 2
(con
tinue
d)
Pref
erre
d te
rmSu
gges
ted
abbr
evia
tions
aR
atio
nale
/exp
lana
tion
Term
s to
avoi
d
Part
5. K
idne
y m
easu
res
App
lies t
o pe
ople
with
or w
ithou
t kid
ney
dise
ase;
con
side
r mea
sure
men
t iss
ues (
met
hods
) and
va
riabi
lity
(mul
tiple
mea
sure
s may
impr
ove
clas
sific
atio
n)G
lom
erul
ar fi
ltrat
ion
rate
an
d cl
eara
nce
GFR
and
cre
atin
ine
clea
ranc
e ar
e no
t syn
onym
ous
GFR
Uni
ts m
ust b
e sp
ecifi
ed (m
l/min
per
1.7
3 m
2 or m
l/min
)
filtra
tion
rate
mG
FRC
lear
ance
met
hods
and
exo
geno
us fi
ltrat
ion
mar
kers
shou
ld b
e no
ted
sepa
rate
ly in
met
hods
filtra
tion
rate
eGFR
Estim
atin
g eq
uatio
ns (e
.g.,
CK
D-E
PI a
nd M
DR
D S
tudy
) and
filtr
atio
n m
arke
rs (e
.g.,
crea
ti-ni
ne a
nd c
ysta
tin C
) sho
uld
be n
oted
sepa
rate
ly in
met
hods
-la
r filtr
atio
n ra
te;
mar
ker
eGFR
creG
FR u
sing
cre
atin
ine
eGFR
cys
eGFR
usi
ng c
ysta
tin C
eGFR
cr-c
yseG
FR u
sing
cre
atin
ine
and
cyst
atin
CC
lSo
lute
mus
t be
spec
ified
; uni
ts m
ust b
e sp
ecifi
ed (m
l/min
per
1.7
3 m
2 or m
l/min
)m
Cl
Cle
aran
ce m
etho
ds a
nd m
arke
rs sh
ould
be
note
d se
para
tely
in m
etho
ds
mar
ker
mC
l UN
mC
l usi
ng u
rea
nitro
gen
mC
l cr
mC
l usi
ng c
reat
inin
em
Cl U
N-c
rm
Cl u
sing
ure
a ni
troge
n an
d cr
eatin
ine
eCl
Estim
atin
g eq
uatio
ns (e
.g.,
Coc
kcro
ft-G
ault)
and
mar
kers
shou
ld b
e no
ted
sepa
rate
ly in
met
h-od
s
mar
ker
eCl cr
eCl u
sing
cre
atin
ine
GFR
cate
gori
esFo
r use
in d
escr
ibin
g G
FR le
vel i
rres
pect
ive
of th
e pr
esen
ce o
r abs
ence
of k
idne
y di
seas
e;
GFR
uni
ts a
re m
l/min
per
1.7
3 m
2 for t
hese
cat
egor
ies;
mul
tiple
cat
egor
ies c
an b
e co
llaps
ed
(e.g
., G
3–G
5)
GFR
G1
GFR
≥m
2
G2
m2
G3a
m2
G3b
m2
G4
m2
G5
GFR
<m
2 or t
reat
ed b
y di
alys
isTh
e co
ncep
t of h
yper
filtra
tion
is g
ener
ally
acc
epte
d bu
t not
con
sist
ently
defi
ned.
If th
is
term
is u
sed
as a
n ex
posu
re, o
utco
me,
or c
ovar
iate
, the
GFR
thre
shol
d m
ust b
e de
fined
(e
.g.,>
m2 )
Rena
l hyp
erfil
tratio
n
The
conc
ept o
f GFR
rese
rve
is g
ener
ally
acc
epte
d as
the
diffe
renc
e be
twee
n st
imul
ated
and
ba
sal G
FRRe
nal f
unct
ion
rese
rve
Alb
umin
uria
and
pro
tein
uria
Spec
ify m
easu
rem
ent c
ondi
tions
(spo
t vs.
timed
sam
ples
; qua
ntita
tive
vs. d
ipst
ick)
; diff
eren
ti-at
e no
n-al
bum
in p
rote
ins a
s clin
ical
ly in
dica
ted
646 Journal of Nephrology (2020) 33:639–648
1 3
Tabl
e 2
(con
tinue
d)
Pref
erre
d te
rmSu
gges
ted
abbr
evia
tions
aR
atio
nale
/exp
lana
tion
Term
s to
avoi
d
Alb
umin
uria
Mic
roal
bum
inur
ia, m
acro
albu
min
uria
co
ncen
tratio
n
excr
etio
n ra
teA
ERRe
quire
s tim
ed u
rine
colle
ctio
n; in
terv
al fo
r urin
e co
llect
ion
shou
ld b
e no
ted
sepa
rate
ly in
cr
eatin
ine
ratio
AC
R Fr
om ti
med
urin
e co
llect
ion
or sp
ot u
rine
colle
ctio
n; in
terv
al fo
r tim
ed u
rine
colle
ctio
n, o
r tim
e of
day
for s
pot u
rine
colle
ctio
n, sh
ould
be
note
d se
para
tely
in m
etho
dsPr
otei
nuri
aC
linic
al p
rote
inur
ia, o
vert
prot
einu
ria
conc
entra
tion
ex
cret
ion
rate
PER
Requ
ires t
imed
urin
e co
llect
ion;
inte
rval
for u
rine
colle
ctio
n sh
ould
be
note
d se
para
tely
in
met
hods
; uni
t of t
ime
may
var
y (h
our o
r day
)
crea
tinin
e ra
tioPC
RFr
om ti
med
urin
e co
llect
ion
or sp
ot u
rine
colle
ctio
n; in
terv
al fo
r tim
ed u
rine
colle
ctio
n, o
r tim
e of
day
for s
pot u
rine
colle
ctio
n, sh
ould
be
note
d se
para
tely
in m
etho
dsA
lbum
inur
ia a
nd
prot
einu
ria
cate
gori
esFo
r use
in d
escr
ibin
g al
bum
inur
ia o
r pro
tein
uria
leve
l irr
espe
ctiv
e of
the
pres
ence
or a
bsen
ce
of k
idne
y di
seas
eA
ER <
<
Nor
moa
lbum
inur
ia
(nor
mal
to m
ild)
A1
AER
<
<
PE
R <
<
(mod
erat
e)A
2M
icro
albu
min
uria
(sev
ere)
A3
AER
>
>
PE
R >
>
Mac
roal
bum
inur
ia, c
linic
al p
rote
inur
ia, o
vert
prot
einu
riad
AER
>
>
PE
R >
>
Spec
ify w
ith o
r with
out n
ephr
otic
synd
rom
e, a
s not
ed b
y th
e pr
esen
ce o
f hyp
oalb
umin
emia
(w
ith e
dem
a an
d hy
perli
pide
mia
in m
ost c
ases
)Tu
bula
r fun
ctio
nTS
Furth
er sp
ecifi
catio
n is
requ
ired
to d
istin
guis
h ra
te, c
lear
ance
, or f
ract
ion
(com
pare
d to
filte
red
load
)TR
Furth
er sp
ecifi
catio
n is
requ
ired
to d
istin
guish
rate,
clea
ranc
e, or
frac
tion
(com
pare
d to
filte
red
load
)
FEN
aFE
of s
odiu
m
mar
ker
FRN
aFR
of s
odiu
m
647Journal of Nephrology (2020) 33:639–648
1 3
studies in children. For these and other reasons, we con-sider the current recommendations for a glossary to be an important starting point, and it will require future expansion and updating.
Achieving consensus among conference attendees, and publication of the conference report and glossary, is only the first step in implementation of a revised nomenclature. The glossary will be freely available on the KDIGO web-site (https ://kdigo .org/confe rence s/nomen clatu re/; Table 2). Elements of the glossary will be included in online updates to the newly released (11th) edition of the AMA Manual of Style [13]. Medical journals adopting the recommendations will need to determine how to implement them, and this process will require education of editorial staff as well as proactive communication with authors, generally and with regard to specific manuscripts. If successful, further imple-mentation in clinical practice, research, and public health will require more widespread dissemination and professional education. Improving communication with patients and the public will require efforts to improve patient education and health literacy for the public, and guides to communication with patients. Professional societies, industry, and patient advocacy organizations will be critical to these efforts.
Advances in research, particularly in precision medicine, will introduce a myriad of new terms and novel concepts requiring incorporation into disease definitions and classi-fications. In addition, the increasing prominence and par-ticipation of patient and caregiver communities in defining research and best practices in clinical care will further elu-cidate the characteristics of patient-centered terminology. Expanding and updating the KDIGO glossary can be accom-plished as part of the activities of future KDIGO guideline workgroups and conferences.
Acknowledgements The authors are grateful to Juhi Chaudhari, MPH, at Tufts Medical Center, Boston, MA for assistance with manuscript preparation. The conference was sponsored by KDIGO and supported in part by unrestricted educational grants from AstraZeneca, Bayer HealthCare, Boehringer Ingelheim, Fresenius Medical Care, Roche, and Sanofi. The content of this article does not necessarily reflect the views or opinions of the journal organizations represented at the confer-ence. Responsibility for the information and views expressed is limited to the coauthors.
Compliance with ethical standards
Conflict of interest ASL declared having received research support from AstraZeneca, National Institute of Diabetes and Digestive and Kidney Diseases, and National Kidney Foundation. K-UE declared having received consultancy fees from Akebia, Bayer, and Genzyme; speaker honoraria from Bayer and Vifor; and research support from Amgen, AstraZeneca, Bayer, Fresenius Medical Care, and Genzyme. NMD declared having equity ownership/stock options from Eli Lilly & Co. MJ declared having received consultancy fees from Astellas, AstraZeneca, GSK, MSD, and Vifor Fresenius Medical Care Renal
AC
R, a
lbum
in-c
reat
inin
e ra
tio; A
ER, a
lbum
in e
xcre
tion
rate
; AK
D, a
cute
kid
ney
dise
ases
and
dis
orde
rs; A
KI,
acut
e ki
dney
inju
ry; A
KIN
, Acu
te K
idne
y In
jury
Net
wor
k; A
RF,
acu
te re
nal f
ail-
ure;
AR
I, ac
ute
rena
l ins
uffici
ency
; ATN
, acu
te tu
bula
r nec
rosi
s; C
GA
, cau
se, G
FR c
ateg
ory,
and
alb
umin
uria
cat
egor
y; C
KD
, chr
onic
kid
ney
dise
ase;
CK
D-E
PI, C
KD
Epi
dem
iolo
gy C
olla
bora
-tio
n; D
DK
T, d
ecea
sed
dono
r kid
ney
trans
plan
t/tra
nspl
anta
tion;
eG
FR, e
stim
ated
glo
mer
ular
filtr
atio
n ra
te; E
SKD
, end
-sta
ge k
idne
y di
seas
e; E
SKF,
end
-sta
ge k
idne
y fa
ilure
; ESR
D, e
nd-s
tage
re
nal d
isea
se; E
SRF,
end
-sta
ge re
nal f
ailu
re; F
E Na,
frac
tiona
l exc
retio
n, s
odiu
m; F
RN
a, fr
actio
nal r
eabs
orpt
ion,
sod
ium
; GFR
, glo
mer
ular
filtr
atio
n ra
te; H
D, h
emod
ialy
sis;
HD
F, h
emod
iafil
tra-
tion;
HF,
hem
ofiltr
atio
n; K
DIG
O, K
idne
y D
isea
se: I
mpr
ovin
g G
loba
l Out
com
es; K
FRT,
kid
ney
failu
re w
ith re
plac
emen
t the
rapy
; KRT
, kid
ney
repl
acem
ent t
hera
py; L
DK
T, li
ving
don
or k
idne
y tra
nspl
ant/t
rans
plan
tatio
n; M
DR
D, M
odifi
catio
n of
Die
t in
Rena
l Dis
ease
; mG
FR, m
easu
red
GFR
; ND
-CK
D, n
on-d
ialy
sis
CKD
; ND
D-C
KD
, non
–dia
lysi
s-de
pend
ent C
KD
; PC
R, p
rote
in-c
re-
atin
ine
ratio
; PD
, per
itone
al d
ialy
sis;
PER
, pro
tein
exc
retio
n ra
te; p
re-E
SRD
, pre
–end
-sta
ge re
nal d
isea
se; R
F, re
nal f
ailu
re; R
IFLE
, Ris
k, In
jury
, Fai
lure
, Los
s of k
idne
y fu
nctio
n, a
nd E
nd-s
tage
ki
dney
dis
ease
; RRT
, ren
al re
plac
emen
t the
rapy
; SC
r, se
rum
cre
atin
ine;
TR
, tub
ular
reab
sorp
tion;
TS,
tubu
lar s
ecre
tion
a Jour
nal s
tyle
will
dic
tate
whe
ther
and
whe
n to
abb
revi
ate
term
sb O
ngoi
ng d
iscu
ssio
n; m
ay b
e re
vise
d by
KD
IGO
AK
I gui
delin
e up
date
c Ong
oing
dis
cuss
ion;
may
be
revi
sed
by K
DIG
O A
KD
con
sens
us c
onfe
renc
ed O
ngoi
ng d
iscu
ssio
n; m
ay b
e re
vise
d by
KD
IGO
Glo
mer
ulon
ephr
itis g
uide
line
upda
te
Tabl
e 2
(con
tinue
d)
648 Journal of Nephrology (2020) 33:639–648
1 3
Pharma; speaker honoraria from Abbvie, Amgen, Menarini, MSD, and Vifor Fresenius Medical Care Renal Pharma; travel support from Amgen; and research support from Alexion, Amgen, Janssen-Cilag, Otsuka, and Roche. WCW declared having received consultancy fees from Akebia, AMAG, Amgen, AstraZeneca, Bayer, Daiichi-Sankyo, Relypsa, and ZS Pharma; speaker honoraria from FibroGen; and re-search support from National Institutes of Health. All the other authors declared no competing interests.
Ethical approval The article does not contain any studies with human participants or animals performed by any of the authors.
Informed consent For this type of study, formal consent is not required.
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