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Infectious Diseases
ISSN: 2374-4235 (Print) 2374-4243 (Online) Journal homepage: http://www.tandfonline.com/loi/infd20
Pitfalls in studies of eosinopenia and neutrophil-to-lymphocyte count ratio
Stamatis Karakonstantis, Dimitra Kalemaki, Emmanouil Tzagkarakis &Charalampos Lydakis
To cite this article: Stamatis Karakonstantis, Dimitra Kalemaki, Emmanouil Tzagkarakis &Charalampos Lydakis (2017): Pitfalls in studies of eosinopenia and neutrophil-to-lymphocyte countratio, Infectious Diseases, DOI: 10.1080/23744235.2017.1388537
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Published online: 26 Oct 2017.
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INFECTIOUS DISEASES,2017; VOL. 0,NO. 0, 1–12
https://doi.org/10.1080/23744235.2017.1388537
REVIEW ARTICLE
Pitfalls in studies of eosinopenia andneutrophil-to-lymphocyte count ratio
Stamatis Karakonstantisa , Dimitra Kalemakib, Emmanouil Tzagkarakisc and Charalampos Lydakisd
aResident of Internal Medicine, Second Department of Internal Medicine, General Hospital of Heraklion ‘Venizeleio-Pananeio’,Heraklion, Greece; bResident of General Medicine, University Hospital of Heraklion, Voutes, Heraklion, Greece; cConsultant inInternal Medicine. Second Department of Internal Medicine, General Hospital of Heraklion ‘Venizeleio-Pananeio’, Heraklion,Greece; dHead of the Second Department of Internal Medicine, Second Department of Internal Medicine, General Hospital ofHeraklion ‘Venizeleio-Pananeio’, Heraklion, Greece
ABSTRACTThere is a number of publications evaluating the eosinophil count and the neutrophil-to-lymphocyte count ratio for diagno-sis, prognosis or monitoring of patients. Of special interest is the use of these parameters for discrimination betweenthe different causes of fever (e.g. bacterial versus viral vs. non-infectious causes of fever) and for monitoring the efficacy oftherapy and predict the course of the patient. However, pitfalls in previous study designs prevent applicability to clinicalpractice. Here, we provide a short review of the relevant literature and summarize important factors that should be takeninto account when designing studies, with special attention to the selection of a proper and clinically meaningful studypopulation and the effects of the stress response and of corticosteroids.
KEYWORDSEosinopeniaEosinophil countNeutrophil-to-lymphocyte count ratioPitfalls
ARTICLE HISTORYReceived 22 August 2017Revised 25 September 2017Accepted 30 September 2017
CONTACTStamatis Karakonstantis
[email protected] of Internal Medicine, 2nd
Department of Internal Medicine, General Hospitalof Heraklion ‘Venizeleio-Pananeio’, LeoforosKnossou, Heraklion, Greece, Postal code 71409
� 2017 Society for Scandinavian Journal of Infectious Diseases
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Introduction
Eosinopenia, neutrophilia and lymphopenia are com-monly observed in patients with infections. Eosinopeniaof acute infection is thought to be the result of seques-tration of eosinophils at the site of infection [1,2],although other stress responses may also result in eosi-nopenia, mediated by adrenal corticosteroids and epi-nephrine [3–5]. Neutrophilia during acute infection is theresult of mobilization of neutrophils from the bone mar-row mediated by chemokines [6], while lymphopeniaresults from re-distribution of lymphocytes within thelymphatic system and apoptosis [7].
There has been some interest in using the eosinophilcount (EC) and the neutrophil-to-lymphocyte-count ratio(NLCR) for diagnostic, prognostic or monitoring purposesin patients with infections. More specifically EC and/orNLCR have been studied for the following purposes: (1)for the differentiation of bacterial from viral infection[8,9], (2) for the differentiation of infectious from non-infectious causes of fever [8–19], (3) as prognosticmarkers (e.g. [14,20–26]), (4) as an early predictor ofresponse to antimicrobial therapy [27], (5) as predictorsof bloodstream infections [28–32] and (6) for the diagno-sis of particular micro-organisms [33–36]. However, mostof these studies have significant limitations. Here, wepresent a short review of the literature and then focuson the pitfalls of previous study designs, in order to aidwith the design of future studies of EC and NLCR.
Short review of the literature
Table 1 summarizes the studies that have evaluatedeosinopenia and NLCR as a diagnostic marker and as apredictor of bacteraemia.
Gil et al [11], in a study conducted in an internalmedicine department, found that an EC of less than 40/ll was a very specific marker in differentiating infectiousfrom non-infectious causes of elevated C-reactive protein(CRP). Later, Efstathiou et al [17] found that an EC <40/ll(in combination with CRP >6mg/dl and ferritin< 500 lg/l) was a good independent marker of infectionin patients with fever of unknown origin. Subsequently,Abidi et al [10] demonstrated that eosinopenia (<50/ll)was a very sensitive and specific marker for identifyingsepsis in patients admitted to the ICU, although otherstudies in the ICU setting failed to reproduce theseresults [12–15]. More recently, profound eosinopenia(<10/ul) was found to be a very specific marker of sepsisin patients presenting to the Emergency Department[16]. As a predictor of bacteraemia eosinopenia has both
low sensitivity and low specificity [28–30]. Of note is thevariable EC cut-off value used in different studies, whichcomplicates the interpretation of studies of EC. Thislikely reflects the variability in the populations studied,as discussed later.
Similar to eosinopenia, the NLCR has been studied asa marker of sepsis, and as a predictor of bacteraemia.For example, Ljungstr€om et al. [19] found that inpatients with suspected sepsis a high NLCR may be auseful biomarker of bacterial sepsis, while a low NRCL(<3) may be useful to rule out bacterial sepsis, althoughthe over diagnostic value of NLCR was low (area underthe curve =0.63). Naess et al. [8] showed that patientswith bacterial infections have a significantly higher NLCRcompared to patients with viral infection or non-infec-tious causes of fever. As a marker of bacteraemia theNLCR has a moderate sensitivity and specificity [31,32].
Eosinopenia and NLCR for prognostic purposes havebeen studied with conflicting results [14,20–26]. Forexample, Abidi et al. [21] found that EC <40/ul at admis-sion to the ICU and during the first 7 days was inde-pendently associated with higher risk of mortality, whileYip et al found that eosinopenia at discharge from theICU was associated with unexpected re-admissions [37].Others have failed to confirm eosinopenia as a predictorof mortality [26], and Merino et al found that the clinicalvalue of eosinopenia as a predictor of mortality is low[20]. Of more interest, perhaps, is persistence of eosino-penia (and high NLCR) in non-survivors compared torapid resolution of eosinopenia (and reduction of theNLCR) in survivors [20–22,26], suggesting that EC andNLCR may be useful monitoring parameters. Forexample, Davido et al. [27] recently reported that initi-ation of correct antimicrobial therapy results in promptresolution of eosinopenia, while eosinopenia persisted inpatients with infections caused by bacteria resistant tothe initial antimicrobial therapy. Despite some limitationsof this study, in our opinion, this is the most promisingclinical application of eosinopenia and warrants confirm-ation in a larger prospective study.
The effect of the stress response and ofcorticosteroids
It is well established that corticosteroids can reduce eosi-nophils, raise neutrophils and reduce lymphocytes[38,39]. Therefore, it is an important confounding factorand receipt of corticosteroids before presentation or inthe emergency department or during the hospital stayshould be taken into account when assessing EC
2 S. KARAKONSTANTIS ET AL.
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Table1.
Summaryof
previous
stud
ieson
eosino
peniaandNLCRas
markers
ofinfectionandbacteraemia.
Stud
ies
Setting-design
Inclusion/exclusioncriteria
Stud
ypo
pulatio
n(num
berof
patients)
Results
Gilet
al.2
003[11]
Internal
MedicineDepartm
ent
– Prospective
– n¼138
Inclusioncriteria:C
RP>
2mg/dl
attwosuccessive
measurements.
Exclusioncriteria:
Corticosteroidsat
admission
,Cushing
synd
rome,
parasitic
disease,
eosino
philicvasculitis,adrenal
insufficiency,lym
phom
a
Infected
(83),
Non
-infected
(55):
Polymyalgiarheumatic/giant
cell
arteritis(21),cancer(10),systemic
vasculitis(5),veno
usthrombo
-em
bolism
(4)sarcoido
sis(3),anky-
losing
spon
dylitis(3),Croh
n’s(2),
fecolith(2),rheumatoidarthritis
(1),thyroiditis
(1),remittingsero-
negativesymmetrical
syno
vitis
with
pittingoedema(1),chon
dro-
calcinosis(1),Sharp(1)
Foreosino
peniaat
acut-off<4
0/ll:
Sensitivity
56%,specificity
92%,
PPV92%,N
PV57%,LRþ
=7
ForCR
Pat
acut-off>1
0mg/dl:
Sensitivity
75%,specificity
72%,P
PV81%,N
PV64%
Efstathiou
etal.2
010[17]
Internal
MedicineDepartm
ent
– Prospective
– n¼213
Inclusioncriteria:
Feverof
unknow
norigin
according
tothecriteria
ofDurackand
Street.
Exclusioncriteria:
Immun
osup
pression
,neutrop
enia,
nosocomialF
UO,m
issing
data,
insufficientbasicwork-up
.
Infections
(69)
Endo
carditis(21),tub
erculosis(17),
brucellosis(7),osteom
yelitis(2),
prostheticjointinfection(1),
leptospirosis(2),pelvicinflamma-
tory
disease(1),intra-abdo
minal
abscess(1),psoasabscess(1),Q
fever(2),Whipp
le’sdisease(1),
Lyme’sdisease(2),cytomegalo-
virus(3),leishm
aniasis(7),sub-
diaphragmaticam
oebadic
abscess(1)
Non
-infections
(144)
Lymph
omas
(14),solid
tumou
rs(8),
system
iclupu
serythematosus
(18),
Still’sdisease(16),vasculiticsyn-
drom
es(28),sarcoidosis(5),
Croh
n’sdisease(1),familial
medi-
terraneanfever(1),TRAP
S(1),
subacute
thyroiditis
(5),recurrent
pulmon
aryem
bolism
(2)
Castleman’sdisease(1),Kikuchi’s
necrotizinglymph
adenitis(1),no
diagno
sis(39)
Eosino
penia(<
40/ll),
CRP>6mg/dl
andferritin<500lg/lw
ereinde-
pend
entmarkers
ofinfectionin
themultivariate
analysis.For
the
diagno
sisof
infection,
thecom-
binedpresence
oftwoor
moreof
thesemarkers
hadasensitivity
of91.4%,specificity
of92.3%,P
PVof
86.5%,N
PV95.2%,p
ositive
likeli-
hood
ratio
11.9
andnegativelike-
lihoodratio
0.09.
Abidie
tal.2
008[10]
Medical
ICU
– Prospective
– n¼177
Inclusioncriteria:C
onsecutive
patientsadmitted
toamedical
ICU
Exclusioncriteria:
Patientswho
died
(n¼12)or
were
discharged
with
in24
hafter
admission
(n¼9)
Infected
(120):
Sepsis(41),severesepsis(55),septic
shock(24)
Non
-infected
1SIRS
(20):
COPD
exacerbatio
n(6),asthma(4),
diabeticketoacidosis(4),acute
poison
ing(3),cardiogenicshock
(2),gastrointestinal
bleeding
(1)
Non
-infected
1no
tSIRS
(37):
Acutepo
ison
ing(30),scorpion
enveno
mation(3),acuteischaemic
stroke
(2),hypercalcaem
ia(2)
Forinfectionversus
non-infection
(ECcut-off<5
0/ll):sensitivity
80%
(95%
CI,7
1–86),specificity
91%
(95%
CI,7
9–96),LRþ
9.12
(95%
CI,3
.9–21),LR-
0.21
(95%
CI,
0.15–0.31)
ForinfectionSIRS
versus
non-infec-
tion
SIRS
(ECcut-off<4
0/ll):
Sensitivity
80%
(95%
CI,7
1–86),
specificity
80%
(95%
CI,5
5–93),
LRþ
4(95%
CI,1
.65–9.65),LR-
0.25
(95%
CI,0
.17–
0.36)
Eosino
peniaversus
CRP(cut-off
>7mg/dl):
(continued)
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Table1.
Continued
Stud
ies
Setting-design
Inclusion/exclusioncriteria
Stud
ypo
pulatio
n(num
berof
patients)
Results
Forinfectionversus
non-infection:
ROCAU
C0.89
(95%
CI,0
.8–0.94)
versus
0.77
(95%
CI,0
.70–0.84)
p<.001
ForinfectionSIRS
vsno
n-infection
SIRS:R
OCAU
C0.84
(95%
CI,
0.74–0.94)
foreosino
phils
versus
0.77
(95%
CI,0
.67–0.87)
p¼.175
Smith
sonet
al.2
009[12]
MedicalICU
– Retrospective
– n¼191
Inclusioncriteria:p
atientsadmitted
tothemedicalICU
Exclusioncriteria:H
IV,h
aematolog
icmalignancies
Infectious
SIRS
(142)
Non
-infectious
SIRS
(49)
Differencesin
eosino
phils
coun
tbetweenthegrou
pswereno
tstatistical
sign
ificant.Eosinop
enia
<40/llw
aspresentin
49.3%
oftheinfected
grou
pandin
36.7%
oftheno
n-infected
grou
pShaabanet
al.2
010[13]
MedicalICU
– Prospective
– n¼68
Inclusioncriteria:C
onsecutive
patientsadmitted
toamedical
ICU
Exclusioncriteria:
Patientswho
died
orweredis-
chargedwith
in24
hafter
admission
Infectiongrou
p(31):
Sepsis(15),severesepsis(11),septic
shock(5)
Non
-infectiongrou
p(37):
Cardiaccond
ition
s(4),tracheal
sten-
osis(1),massive
non-parapn
eu-
mon
icpleurale
ffusion
(2),
hypercapnicrespiratory
failure
(3),
COPD
exacerbatio
n(2),PE
(1),
severe
electrolyteimbalance-
alteredmentalstatus(4),anaemia
(3),drug
intoxicatio
n(3),GIb
leed-
ing(4),DKA
(2),acutecerebrovas-
cularaccidents(3),status
epilepticus
(3)
Atacut-offof
<50/lle
osinop
enia
yieldedasensitivity
of81%,speci-
ficity
65%,P
PV66%,N
PV80%.
AUCof
ROC0.72
(95%
CI0.6–0.83)
Atacut-offof
7mg/dl
CRPyielded
asensitivity
of94%,specificity
84%,P
PV83%,N
PV94%,A
UCof
ROC0.92
(95%
CI0.83–0.97)
Procalcitoninat
acut-offof
1.5ng
/mlyieldedasensitivity
of84%,
specificity
92%,P
PV90%,N
PV80%,A
UCof
ROC0.89
(95%
CI0.79–0.95
Garnacho-Mon
tero
Jet
al.2
014[14]
Medico-surgical
ICU
– Prospective
– n¼163
Inclusioncriteria:
Alla
dultpatientsadmitted
toamed-
ico-surgical
ICUandfulfilling
the
SIRS
criteria.
Exclusioncriteria:
Activemalignancy,acutemyocardial
infarctio
nin
thelast
mon
th.
Infectious
SIRS
(117):
Severe
sepsis(44),septic
shock(73)
Non
-infectious
SIRS
(43):
acuterespiratory
failure
(13),early
post-operativecourse
ofabdo
m-
inalsurgery(8),acutepancreatitis
(8),multip
letrauma(2),febrile
synd
romein
conn
ectivetissuedis-
ease
(2)
Eosino
phils
<25/ll:sensitivity
65%,
specificity
29%,P
PV62%,N
PV23%,A
UCRO
C0.54
CRP>1
0.38
mg/dl:sensitivity
91%,
specificity
41%,P
PV81%,N
PV61%
Procalcitonin>1
.39ng
/ml:sensitivity
91,specificity
67%,P
PV88%,N
PV74%
Anandet
al.2
016[15]
MedicalICU
– Prospective
– n¼170
Inclusioncriteria:
Alla
dultpatientsadmitted
toamed-
icalICUwith
SIRS.
Exclusioncriteria:
Patientstransferredfrom
otherICUs,
post-operative,immun
ocom
prom
-ised,p
regn
ant,activemalignancy,
thosewho
died
orweredis-
chargedin
thenext
24h,
patients
with
bilateralp
neum
onia
(sus-
pected
viralinfectio
n)andpatients
Infectious
SIRS
(125):
Non
-infectious
SIRS
(45):
Acutepancreatitis(25),traum
a(20)
Nosign
ificant
diffe
rencein
the
eosino
philcoun
tbetweenthetwo
grou
ps.
Eosino
peniaat
acut-offof
<50/ll:
sensitivity
23%,specificity
69%,
PPV67%,N
PV24%,A
UCRO
C0.454
Procalcitoninat
cut-offof
>3.13ng
/ml:sensitivity
82.4%,specificity
82.2%,P
PV93%,N
PV63%,A
UC
ROC0.907
(continued)
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Table1.
Continued
Stud
ies
Setting-design
Inclusion/exclusioncriteria
Stud
ypo
pulatio
n(num
berof
patients)
Results
with
trop
icaldiseases
(e.g.m
alaria,
deng
ue,leptospira,rickettesiae)
LavoignetCE
etal.2
016[16]
EmergencyDepartm
ent
– Retrospective
– n¼692
Inclusioncriteria:A
llpatientspre-
sentingto
theem
ergencydepart-
ment.
Exclusioncriteria:immun
odeficiency,
immun
ossupressive
therapy,
patientson
corticosteroids,
chem
otherapy,activemalignancy,
haem
atolog
icmalignancies,
ongo
ingantib
iotic
therapyat
presentatio
n
Sepsisgrou
p(125)
Sepsis(108),severe
sepsis(16),septic
shock(1).
Nosepsisgrou
p(567)
Other
patientsvisitin
gtheED
Eosino
peniaat
acut-offof
<10/ll
yieldedaspecificity
of91%
for
sepsis.Sensitivity
46.4%,P
PV53%,
NPV
88.5%
Meaneosino
philcoun
ts:
Non
-infected:1
30/ul
Infected
with
outSIRS:1
48/ul
Sepsistotal:54/ul
Severe
sepsis:2
7/ul
Gucyetm
ezet
al.2
016[18]
Medico-surgical
ICU
– Retrospective
– n¼1257
Inclusioncriteria:
Adultpatientsadmitted
toamedico-
surgical
ICUandfulfilling
SIRS
cri-
teria.
Exclusioncriteria:
Age<18
yearsold(334),re-adm
itted
(53),d
iagn
osed
with
haem
ato-
logicald
isease,o
ncorticosteroid
andimmun
osup
pressive
therapy
(n¼345),SIRSnegative(318),cul-
ture
negativesepsis(45),u
ndocu-
mentedlabo
ratory
values
and
outcom
es(301)
Sepsisgrou
p(441)
Non
-sep
sisSIRS
(816)
Electivesurgery(540),em
ergency
surgery(36),m
edical
diseases
(240)
Eosino
philcoun
tdidno
tdiffe
rsig-
nificantly
betweenthetwo
grou
ps.
Ljun
gstr€ om
etal.2
017[19]
Emergencydepartment
– Prospective
– n=1572
Inclusioncriteria:
Consecutiveadultpatientsadmitted
totheED
forsuspectedcommu-
nity-onset
sepsis.
Exclusioncriteria:
Noexclusioncriteria
Bacterialinfections
(n=874)
Bacterialsepsis(Sep
sis-2criteria)
(n=667)
Severe
sepsis/sep
ticshock(Sep
sis-2
criteria)(n=169)
Sepsisaccordingto
Sepsis-3
criteria
(n=560)
Others(n=698)
Non
-verified
bacterialinfectio
nor
aviralinfectio
nor
ano
n-infectious
disease
AUCof
NLCRfordiagno
sisbacter-
aemia:0
.71;
95%
CI0.67–0.75.
AUCof
NLCRfordiscrim
inatingbac-
terialinfectio
nsfrom
‘others’:0
.63;
95%
CI0.61–0.66
AUCof
NLCRfordiagno
sing
sepsis
(according
toSepsis3):0
.67;
95%
CI0.64–0.69
Procalcitoninwas
notsign
ificantly
better
comparedto
NLCR.
Naess
etal.2
013[9]and2017
[8]
Internal
MedicineDepartm
ent
– Retrospective
– n¼299
Inclusioncriteria:
Retrospectiveselectionof
patients
admitted
totheho
spitalw
itha
diagno
sisof
‘fever’with
outany
otherdiagno
sissugg
estin
gthe
causeof
fever.
Exclusioncriteria:
Patientswith
leukaemia.P
atients
with
adiagno
sisat
admission
(e.g.
‘fever,pn
eumon
ia’).
Infectionconfirmed
withmicrobiol-
ogy,
serology
orradiolog
y(n=185)
Clinically
diag
nosedinfection
(n=73)
Bacterial(n=150)
Viralinfection(n=14)
Infectious
mon
onucleosis(n¼9)
NLCRwas
sign
ificantlyhigh
erin
patientswith
bacterialinfectio
n(com
paredto
viralinfectio
nsor
noinfection).Thiswas
morepro-
noun
cedin
patientswith
feverof
less
than
oneweek’sdu
ratio
nNLCRwas
sign
ificantlyhigh
erin
patientswith
‘septicaemia’com-
paredto
patientswith
otherbac-
terialinfectio
ns.
NLCRwas
anindepend
entpredictor
(continued)
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Table1.
Continued
Stud
ies
Setting-design
Inclusion/exclusioncriteria
Stud
ypo
pulatio
n(num
berof
patients)
Results
Autoimmun
ediseases
(n=8)
Maligna
ncy(n=5)
Miscellane
ous(n=16)
Nodiag
nosis(n=12)
ofthediagno
sticcatego
ry(bacter-
ialinfectio
nversus
viralinfectio
nvs.clinicallydiagno
sedinfection)
inpatientswith
feverdu
ratio
n<7
days.
deJageret
al.2
010[32]
EmergencyDepartm
ent
– Retrospective
– n¼184
Inclusioncriteria:
Consecutiveadultpatientsadmitted
totheED
with
suspectedcommu-
nity-acquiredbacteraemia.
Exclusioncriteria:
Haematolog
ical
disease,patients
receivingchem
otherapy
orglucocorticoids
Withba
cteraemia
(n=92)
Witho
utba
cteraemia
(n=92)
Ninety-twoage-
andgend
er-m
atched
patientswith
suspectedbacter-
aemia.Eighty-fivehadan
infec-
tious
diagno
sisafterclinical
and
microbiolog
ical
assessment.
NLCRwas
abetter
predictorof
bac-
teraem
iacomparedto
CRP,
WBC
and
neutroph
ilcoun
t.At
acut-off>10:
Sensitivity
77.2%,specificity
63%,
PPV67.6%,N
PV73.4%,A
UC0.73
(95%
CI,0
.66–0.81).
Hoet
al.2
009[28]
ICU
– Retrospective
– n¼66
Inclusioncriteria:
Adultpatientsadmitted
toan
ICU
with
bacteraemia.Twocontrols,
thepatient
who
was
admitted
totheICUimmediatelybefore
and
afterthe‘case’,w
ereselected
con-
currently
foreach
bloodstream
infection‘case’.W
hether
controls
hadbloodcultu
restakenisno
tdescrib
ed.
Exclusioncriteria:
Positivebloodcultu
redu
eto
con-
tamination.
Leukop
enia
dueto
haem
atolog
icdiseaseor
chem
otherapy.
Patien
tswithba
cterem
ia(n=22)
Infected
pancreatitis(n¼1),n
ecrotiz-
ingfasciitis(n¼2),p
neum
onia
(n¼7),catheter-relatedsepsis
(n¼2),w
ound
infection(n¼2),
infectiveendo
carditis(n¼1),p
eri-
tonitis
(n¼1),cellulitis(n¼1),
urinarytractinfection(n¼5)
Controls(n=44)
Pneumon
ia(n¼4),m
ultip
letrauma
(n¼4),cardiog
enicshock(n¼1),
drug
overdo
se(n¼5),valve
replacem
ent(n¼3),sub
arachn
oid
haem
orrhage(n¼4),m
eningitis
(n¼1),coron
aryartery
bypass
(n¼4),g
astrointestin
alob
struc-
tion(n¼1),ischaem
iclegam
pu-
tatio
n(n¼1),intracranial
haem
atom
a(n¼2),asthm
a(n¼1),o
ralabscess
(n¼3),h
yper-
osmolar
non-ketotic
coma(n¼1),
spinal
injuries(n¼1),cardiac
arrest
(n¼1),ischaem
icbo
wel
disease(n¼1),encephalitis
(n¼1),acute
pulmon
aryoedema
(n¼1),intra-abd
ominal
sepsis
(n¼2),b
urns
(n¼2)
Althou
ghEC
was
sign
ificantlylower
inpatientswith
bacteraemia,and
eosino
peniawas
notan
independ
-entpredictorof
bacteraemia.
Setterberg
etal.2
004[29]
Internal
medicine
– Retrospective
– n¼17
Inclusioncriteria:
Retrospectiveselectionof
patients
with
bloodcultu
respo
sitivefor
Gram-negativebacilli,
Staphylococcus
aureus,and
Streptococcusspecies.Ag
e-and
sex-matched
controlp
atientswith
negativebloodcultu
res.
Exclusioncriteria:
Immun
osup
pressedpatients,
Patien
tswithba
cterem
ia(n=171)
Controls(n=174)
‘Noutility
associated
with
eosino
pe-
nia(defined
asarelativeeosino
-ph
illevelo
f0%
)forpredictin
gbacteraemia.’‘The
absenceof
per-
ipheralb
lood
eosino
phils
cann
otbe
used
asaclinicallyreliable
markerof
bacteraemicinfection.’
(continued)
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Table1.
Continued
Stud
ies
Setting-design
Inclusion/exclusioncriteria
Stud
ypo
pulatio
n(num
berof
patients)
Results
neutropenia
Wibrow
etal.2
011[30]
Teaching
hospital
– Retrospective
– n¼531
Inclusioncriteria:
Consecutivepatientswith
apo
sitive
bloodcultu
re(‘cases’)andconcur-
rent
rand
omlyselected
‘con
trols’
(negativebloodcultu
re)with
sus-
picion
ofbloodstream
infection.
Exclusioncriteria:
coagulase-negativestaphylococcus
species,antib
iotic
usethepast
week,haem
atolog
icdisorder,
immun
odeficiency,chem
otherapy,
immun
osup
pressive
therapy(e.g.
corticosteroids,metho
trexate,
cyclospo
rin)
Adu
ltpa
tien
tswithbloo
dstream
infection(n=157)
Paed
iatricpa
tien
tswithbloo
d-stream
infection(n=85)
Adu
ltcontrols(n=195)
Paed
iatriccontrols(n=94)
EC<10/lla
sapredictorof
blood-
stream
infectionin
adultpatients:
sensitivity
47%,specificity
79%,
AUC0.651(95%
CI0.712–0.589).
ECwas
notsign
ificantlydiffe
rent
betweencasesandcontrolsin
paediatricpatients)
Lowsbyet
al.2
015[31]
EmergencyDepartm
ent
– Retrospective
– n¼1954
Inclusioncriteria
Adultpatientswith
pyrexial
illness
(tym
panictemperature
>37.9
� C,
ormeetin
gcriteria
forsepsis,that
is,SIRSdu
eto
suspectedinfec-
tion).P
atientswereselected
ifthey
hadbloodcultu
resdraw
n.Exclusioncriteria:
Haematolog
icalmalignancy,chem
o-therapytreatm
ent,patientson
corticosteroid
therapy.False-po
si-
tivebloodcultu
res,attributed
toskin
contam
ination,
wereexclud
edfrom
thefin
alanalysis.
True
-positivebloo
dcultures
(n=270)
Forpredictin
gbacteraemiatheNLCR
atacut-off>10
hadasensitivity
of70%,specificity
57%,P
PV20%,
NPV
92%.
‘Alth
ough
NLCRou
tperform
sconven-
tional
markers
ofinfection,
itisinsufficient
initselfto
guideclinical
manage-
mentof
patientswith
suspected
bloodstream
infectionandit
offers
noadvantageover
lymph
o-cyte
coun
t’
AUC:
area
underthecurve;
CI:confidence
interval;LRþ:
positivelikelihoodratio
n;LR�:
negativelikelihoodratio
;NPV
:negativepredictivevalue;
PPV:
positivepredictivevalue;
ROC:
receiver
operatingcharacteristic
curve.
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and NLCR. Some interesting studies of EC and NLCRhave failed to take this into consideration. For example,Davido et al. [27], who described the value of monitor-ing eosinophil counts to assess the efficacy of antimicro-bial therapy, only excluded patients receivingcorticosteroids at a dose >60mg/day and did not reportwhether patients had been given corticosteroids at pres-entation to the emergency department or during hos-pital stay. Similarly, Naess et al. [8] who described NLCRas a useful marker to discriminate between differentcauses of fever, did not comment on whether includedpatients were taking corticosteroids, although a clarifica-tion was later published in response to our correspond-ence [40,41]. Other studies evaluating eosinopenia as adiagnostic marker have also failed to take this factorinto account [10,12–15,17,36] and the same applies tomany of the prognostic studies [14,24–26], and some ofthe studies of EC and NLCR as predictors of bacteraemia[28,29]. Some studies do comment on the use of cortico-steroids in included patients but did not exclude suchpatients from analysis [20–22].
Other conditions that may elicit a systemic inflamma-tory response or any acute stress may have a similareffect on EC and NLCR as in patients with infection. Forexample, we have found eosinopenia (<50/ll) in a sig-nificant percentage of patients with acute pancreatitis
and acute upper gastrointestinal bleeding (23 of 39patients and 29 of 55 patients, respectively – unpub-lished retrospective data). Others have described eosino-penia or high NLCR in other acute conditions, forexample, acute myocardial infarction (e.g. [42,43]), stroke(e.g. [44–46]), acute trauma (e.g. [47,48]) and even dur-ing emotional stress [5]. Therefore, as previously sug-gested [12–14,18], eosinopenia cannot be considered asa specific marker of sepsis, and any concurrent acutestress may affect EC or NLCR and should be taken intoaccount if possible.
Pitfalls in using EC and NLRC to differentiateinfections from non-infectious diseases
For this purpose of differentiating infectious from non-infectious illness, an ideal study sample would bepatients with an unclear diagnosis at presentation,including both infectious and non-infectious diseases inthe initial differential diagnosis (Figure 1). Includingpatients with an obvious ‘non-infection’ diagnosis mayresult in an inaccurate estimation of the diagnostic spe-cificity of EC or NLCR, while including patients with anobvious infectious disease would most likely result in anoverestimation of the diagnostic sensitivity (Figure 1).Results from a study, which includes patients with obvi-ous infectious or non-infectious diagnoses, would not be
Figure 1. The ideal study population for studying the diagnostic accuracy of eosinophil count (EC) or neutrophil-to-lymphocyte count ratio(NLCR) in differentiating infection from non-infection.
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clinically useful. For example, a physician would notneed to check the EC or the NLCR to confirm pneumo-nia in a patient with fever, productive cough and a newlobar infiltrate on chest x-ray. The same applies to apatient with an obvious, typical exacerbation of a knownautoimmune or rheumatologic disease or a patientadmitted due to drug overdose.
Reviewing the relevant publications [10–16] (Table1), the study populations were far from ideal. Forexample, Abidi et al. [10], who reported that eosinope-nia is a reliable marker of sepsis in patients admittedto the intensive care unit, included several patientswith obvious non-infectious diagnoses and without areason to suspect an infection (e.g. 33 of 57 patientsin the non-infection group were admitted due toacute poisoning, two patients had hypercalcaemia andthree patients were admitted due to scorpionenvenomation). Similarly, the inclusion criterion for thestudy by Gil et al. [11] was a CRP above 2mg/dl,while the non-sepsis group in the study by Lavoignetet al. [16] included all patients presenting to theemergency department irrespective of the reason.Therefore, none of these three studies that favouredthe use of eosinopenia as a diagnostic markerincluded a clinically meaningful study population. Onthe other hand, studies that did not support eosinope-nia as a diagnostic marker of sepsis [12–14,18] alsofailed to include an appropriate study population. Forexample, including in the non-sepsis group acutetrauma patients, post-surgical patients, patients withpancreatitis or patients with acute bleeding (i.e. non-infectious conditions that may also produce an eosino-penic response and a high NLCR) in the absence ofsuspected infection, will result in underestimated diag-nostic specificity of eosinopenia or NLCR. On the con-trary, a study of patients with fever of unknown originidentified eosinopenia as a good independent pre-dictor of infection [17].
Pitfalls in using EC and NLCR to differentiatebacterial from viral infection
A study on the differentiation of bacterial from viralinfections should include a clear description of how aviral or bacterial infection is defined, as well as adetailed description of patients included in the study.This is important to allow proper interpretation of theresults. For example, Naess et al. [8,9] described NLCR asa useful marker to discriminate viral from bacterial infec-tion. However, a significant portion of patients in the
‘viral infection’ group had infectious mononucleosis (9 of14 patients), that is, a viral infection typically associatedwith lymphocytosis, therefore limiting the applicability oftheir results to other more common viral infections. Also,patients with a confirmed viral infection (e.g. H1N1 con-firmed with RT-PCR), may have concurrent bacterialsuperinfections, further complicating the interpretationof the results.
Considering that the value of differentiating a viralfrom a bacterial infection would be to guide treatmentwith antibiotics, it might be more useful to compare ECor NLCR of patients successfully managed without antibi-otics to patients that required antibiotic treatment(instead of comparing and trying to define, viral vs. bac-terial infection). Other parameters, like the severity ofthe disease or the presence of SIRS criteria, should betaken into account. Whether the EC or NLRC simplyreflect these parameters or may have additional valuerequires further investigation.
Pitfalls in monitoring EC or NLCR to assessresponse to antimicrobial therapy
As mentioned above, Davido et al. [27] recentlyreported that monitoring the EC may be useful to pre-dict the efficacy of the selected antimicrobial regimen.For such a study, ideally the two groups of patients(correct vs. incorrect antibiotic regimen) should bematched in terms of diagnoses and initial antibioticregimens, and patients receiving corticosteroids (anydose) at presentation or during hospital stay shouldbe excluded. The development of eosinophilic drugreactions during antibiotic treatment should also berecorded as this may cause a rise of the EC, irrespect-ive of response to therapy. Of note is that asymptom-atic eosinophilia (>500/ll) is not uncommon duringintravenous antibiotic treatment, and although it usu-ally occurs later in the course of therapy [49], it mayoccur during the first days of treatment [50],which can be an important confounding factor.Furthermore, although early-onset eosinophilia is usu-ally accompanied by signs of allergy, a milder asymp-tomatic rise of EC as a reaction to the administrationof antibiotics cannot be ruled out. Moreover, eosino-philia occurs more often with some antibiotics thanothers [49] and some antibiotics may act faster thanother. For these reasons, it is important that the twogroups of patients should be matched in terms of theinitial antibiotic regimen. The route of administrationmay also be important and should be matched
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between the two groups, as allergic reactions (and theassociated rise of the EC) may be more common fol-lowing parenteral compared to oral administration [51].
Other considerations
Some other issues that should be taken into accountwhen designing studies of EC and NLCR are thefollowing:
1. Patients with infection but with a high baselineeosinophil count due to other concurrent conditions(e.g. chronic rhinitis, asthma, atopic dermatitis, para-sitic disease, some malignancies, autoimmune dis-eases, etc. [52]) may be less likely to present with anEC lower than the defined cut-off. In such patients,the change of EC from the baseline (if known) maybe a more accurate, but impractical, marker.
2. The accuracy of haematology instruments in measur-ing low EC may be low [53].
3. The presence of active haematological malignancies,cytotoxic chemotherapy and HIV infection may alterthe complete blood count parameters and suchpatients should be excluded from studies evaluatingEC or NLCR or studied as a separate group.
4. Antibiotic use before presentation to the hospitalshould be taken into account, and it may be appro-priate to exclude such patients [16], as an appropri-ate antibiotic regimen might result in fast resolutionof eosinopenia [27].
Conclusions
Although there are many publications regarding thevalue of EC and NLCR for diagnostic, prognostic or moni-toring purposes, significant pitfalls limit the applicabilityof these results to clinical practice. Considering the lowcost and the fact that a complete blood count is avail-able in all patients admitted to hospital, it may be worthinvestigating the value of EC or NLCR in properlydesigned prospective studies. Monitoring EC to predictthe efficacy of antimicrobial therapy seems to be apromising clinical application that requires validation inlarger studies.
Disclosure statement
The authors report no conflicts of interest
ORCID
Stamatis Karakonstantis http://orcid.org/0000-0002-2643-3184
References
[1] Bass DA. Behavior of eosinophil leukocytes in acute inflam-mation. II. eosinophil dynamics during acute inflammation.J Clin Invest. 1975;56:870–879.
[2] Bass DA, Gonwa TA, Szejda P, et al. Eosinopenia of acuteinfection: production of eosinopenia by chemotactic factorsof acute inflammation. J Clin Invest. 1980;65:1265–1271.
[3] Best WR, Muehrcke RC, Kark RM. Studies on adrenocorticaleosinopenia: a clinical and statistical evaluation of four-hour eosinophil response test. J Clin Invest. 1952;31:733–742.
[4] Hills AG, Forsham PH, Finch CA. Changes in circulating leu-kocytes induced by the administration of pituitary adreno-corticotrophic hormone in man. Blood. 1948;3:755–768.
[5] Dreyfuss F, Feldman S. Eosinopenia induced by emotionalstress. Acta Med Scand. 1952;144:107–113.
[6] Summers C, Rankin SM, Condliffe AM, et al. Neutrophil kin-etics in health and disease. Trends Immunol.2010;31:318–324.
[7] Zahorec R. Ratio of neutrophil to lymphocyte counts-rapid and simple parameter of systemic inflammationand stress in critically ill. Bratisl Lek Listy. 2001;102:5–14.
[8] Naess A, Nilssen SS, Mo R, et al. Role of neutrophil tolymphocyte and monocyte to lymphocyte ratios in thediagnosis of bacterial infection in patients with fever.Infection. 2017;45:299–307.
[9] Naess A, Mo R, Nilssen SS, et al. Infections in patientshospitalized for fever as related to duration andother predictors at admittance. Infection. 2014;42:485–492.
[10] Abidi K, Khoudri I, Belayachi J, et al. Eosinopenia is a reli-able marker of sepsis on admission to medical intensivecare units. Crit Care. 2008;12:R59.
[11] Gil H, Magy N, Mauny F, et al. Value of eosinopenia ininflammatory disorders: an "old" marker revisited. Rev MedInterne. 2003;24:431–435.
[12] Smithson A, Perello R, Nicolas JM. Is eosinopenia a reliablemarker of sepsis? Crit Care. 2009;13:409.
[13] Shaaban H, Daniel S, Sison R, et al. Eosinopenia: is it agood marker of sepsis in comparison to procalcitonin andC-reactive protein levels for patients admitted to a criticalcare unit in an urban hospital? J Crit Care. 2010;25:570–575.
[14] Garnacho-Montero J, Huici-Moreno MJ, Gutierrez-PizarrayaA, et al. Prognostic and diagnostic value of eosinopenia, C-reactive protein, procalcitonin, and circulating cell-free DNAin critically ill patients admitted with suspicion of sepsis.Crit Care. 2014;18:R116.
[15] Anand D, Ray S, Bhargava S, et al. Exploration of eosinope-nia as a diagnostic parameter to differentiate sepsis fromsystemic inflammatory response syndrome: results from anobservational study. Indian J Crit Care Med.2016;20:285–290.
[16] Lavoignet CE, Le Borgne P, Slimani H, et al. Relevance ofeosinopenia as marker of sepsis in the EmergencyDepartment. Rev Med Interne. 2016;37:730–734.
10 S. KARAKONSTANTIS ET AL.
Dow
nloa
ded
by [
Tuf
ts U
nive
rsity
] at
11:
55 2
7 O
ctob
er 2
017
[17] Efstathiou SP, Pefanis AV, Tsiakou AG, et al. Fever ofunknown origin: discrimination between infectious andnon-infectious causes. Eur J Intern Med. 2010;21:137–143.
[18] Gucyetmez B, Atalan HK. C-reactive protein and hemogramparameters for the non-sepsis systemic inflammatoryresponse syndrome and sepsis: what do they mean? PLoSOne. 2016;11:e0148699.
[19] Ljungstrom L, Pernestig AK, Jacobsson G, et al. Diagnosticaccuracy of procalcitonin, neutrophil-lymphocyte countratio, C-reactive protein, and lactate in patients with sus-pected bacterial sepsis. PLoS One. 2017;12:e0181704.
[20] Merino CA, Martinez FT, Cardemil F, et al. Absolute eosino-phils count as a marker of mortality in patients with severesepsis and septic shock in an intensive care unit. J CritCare. 2012;27:394–399.
[21] Abidi K, Belayachi J, Derras Y, et al. Eosinopenia, an earlymarker of increased mortality in critically ill medicalpatients. Intensive Care Med. 2011;37:1136–1142.
[22] Terradas R, Grau S, Blanch J, et al. Eosinophil count andneutrophil-lymphocyte count ratio as prognostic markers inpatients with bacteremia: a retrospective cohort study.PLoS One. 2012;7:e42860.
[23] Rahimi-Rad MH, Asgari B, Hosseinzadeh N, et al.Eosinopenia as a marker of outcome in acute exacerbationsof chronic obstructive pulmonary sisease. Maedica (Buchar).2015;10:10–13.
[24] Steer J, Gibson J, Bourke SC. The DECAF Score: predictinghospital mortality in exacerbations of chronic obstructivepulmonary disease. Thorax. 2012;67:970–976.
[25] Hwang SY, Shin TG, Jo IJ, et al. Neutrophil-to-lymphocyteratio as a prognostic marker in critically-ill septic patients.Am J Emerg Med. 2017;35:234–239.
[26] Escobar-Valdivia EJ, Gonzalez-Aguirre JE, Carrillo-CisnerosER, et al. Eosinophil count at intensive care unit admissionwas not predictor of hospital mortality: results of a casecontrol study. J Intensive Care. 2015;3:27.
[27] Davido B, Makhloufi S, Matt M, et al. Changes in eosinophilcount during bacterial infection: revisiting an old marker toassess the efficacy of antimicrobial therapy. Int J Infect Dis.2017;61:62–66.
[28] Ho KM, Towler SC. A comparison of eosinopenia and C-reactive protein as a marker of bloodstream infections incritically ill patients: a case control study. Anaesth IntensiveCare. 2009;37:450–456.
[29] Setterberg MJ, Newman W, Potti A, et al. Utility of eosino-phil count as predictor of bacteremia. Clin Infect Dis.2004;38:460–461.
[30] Wibrow BA, Ho KM, Flexman JP, et al. Eosinopenia as adiagnostic marker of bloodstream infection in hospitalisedpaediatric and adult patients: a case-control study. AnaesthIntensive Care. 2011;39:224–230.
[31] Lowsby R, Gomes C, Jarman I, et al. Neutrophil to lympho-cyte count ratio as an early indicator of blood stream infec-tion in the emergency department. Emerg Med J.2015;32:531–534.
[32] de Jager CP, Wever PC, Gemen EF, et al. The neutrophil-lymphocyte count ratio in patients with community-acquired pneumonia. PLoS One. 2012;7:e46561.
[33] Matono T, Kutsuna S, Kato Y, et al. Role of classic signs asdiagnostic predictors for enteric fever among returned trav-ellers: relative bradycardia and eosinopenia. PLoS One.2017;12:e0179814.
[34] Farmakiotis D, Varughese J, Sue P, et al. Typhoid Fever inan inner city hospital: a 5-year retrospective review.J Travel Med. 2013;20:17–21.
[35] Farmakiotis D, Ntouloulis C, Mihailidis N, et al. Diagnosticvalue of eosinopenia in non-Typhi Salmonella enteritis. ClinInfect Dis. 2014;59:1197–1198.
[36] Flick H, Drescher M, Prattes J, et al. Predictors of H1N1influenza in the emergency department: proposition for amodified H1N1 case definition. Clin Microbiol Infect.2014;20:105–108.
[37] Yip B, Ho KM. Eosinopenia as a predictor of unexpected re-admission and mortality after intensive care unit discharge.Anaesth Intensive Care. 2013;41:231–241.
[38] Altman LC, Hill JS, Hairfield WM, et al. Effects of corticoste-roids on eosinophil chemotaxis and adherence. J ClinInvest. 1981;67:28–36.
[39] Shoenfeld Y, Gurewich Y, Gallant LA, et al. Prednisone-induced leukocytosis. Influence of dosage, method and dur-ation of administration on the degree of leukocytosis. Am JMed. 1981;71:773–778.
[40] Karakonstantis S, Kalemaki D. Correspondence to "Role ofneutrophil to lymphocyte and monocyte to lymphocyteratios in the diagnosis of bacterial infection in patients withfever". Infection. 2017 Sep 8. [Epub ahead of print].
[41] Naess A, Eide GE, Sjursen H. Reply to Drs. Karakonstantisand Kalemaki. Infection. 2017.
[42] Kirkeby K. Diagnostic and prognostic significance of eosino-penia in acute myocardial infarction. Am J Med Sci.1956;232:50–56.
[43] Lee MJ, Park SD, Kwon SW, et al. Relation between neutro-phil-to-lymphocyte ratio and index of microcirculatoryresistance in patients with ST-segment elevation myocardialinfarction undergoing primary percutaneous coronary inter-vention. Am J Cardiol. 2016;118:1323–1328.
[44] Bolayir A, Cigdem B, Gokce SF, et al. The effect ofeosinopenia on mortality in patients with intracerebralhemorrhage. J Stroke Cerebrovasc Dis. 2017;26:2248–2255.
[45] Wang F, Hu S, Ding Y, et al. Neutrophil-to-lymphocyteratio and 30-day mortality in patients with acute intracere-bral hemorrhage. J Stroke Cerebrovasc Dis. 2016;25:182–187.
[46] Sun Y, You S, Zhong C, et al. Neutrophil to lymphocyteratio and the hematoma volume and stroke severity inacute intracerebral hemorrhage patients. Am J Emerg Med.2017;35:429–433.
[47] Dilektasli E, Inaba K, Haltmeier T, et al. The prognostic valueof neutrophil-to-lymphocyte ratio on mortality in criticallyill trauma patients. J Trauma Acute Care Surg.2016;81:882–888.
[48] Chen W, Yang J, Li B, etet al. Neutrophil to lymphocyteratio as a novel predictor of outcome in patients withsevere traumatic brain injury. J Head Trauma Rehabil. 2017.[Epub ahead of print]. doi: 10.1097/HTR.0000000000000320
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[49] Blumenthal KG, Youngster I, Rabideau DJ, et al. Peripheralblood eosinophilia and hypersensitivity reactions amongpatients receiving outpatient parenteral antibiotics.J Allergy Clin Immunol. 2015;136:1288–1294 e1.
[50] Ramirez E, Medrano-Casique N, Tong HY, et al. Eosinophilicdrug reactions detected by a prospective pharmacovigi-lance programme in a tertiary hospital. Br J Clin Pharmacol.2017;83:400–415.
[51] Warrington R, Silviu-Dan F. Drug allergy. Allergy AsthmaClin Immunol. 2011;7:S10.
[52] Kovalszki A, Weller PF. Eosinophilia. Prim Care.2016;43:607–617.
[53] Amundsen EK, Urdal P, Henriksson CE. Poor accuracy of theeosinophil count of hematology instruments limits the useof eosinopenia as a marker of bacterial infection orincreased mortality. Int Jnl Lab Hem. 2015;37:e119–e122.
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