PROTOCOL OPEN
In es iga ing he accu acy, isk impac , and cos -e ec i eness
o componen - esol ed diagnos ic es o ood alle gy: a
sys ema ic e iew p o ocol
Ja ie Flo es Kim
1
, B igh I. Nwa u
1,2
, Nicola McClea y
1
, And ew S odda
1,3
and Aziz Sheikh
1
npj P ima y Ca e Respi a o y Medicine (2017) 27:10 ; doi:10.1038/s41533-017-0015-0
BACKGROUND
Food alle gy—pa icula ly immunoglobulin E (IgE)-media ed ood
alle gy—is now a global public heal h p oblem. I esul s in
conside able mo bidi y, heal hca e u ilisa ion, and impai men in
quali y o li e.
1–6
Food alle gy eac ions ange in se e i y om
ela i ely mild ea u es o li e- h ea ening anaphylaxis.
2,3
Es i-
ma es o he p e alence o ood alle gy a y, bu o e all li e ime
p e alence has been es ima ed as a ec ing up o 7% o child en
and 6% o adul s.
4,5
Ca e ul a oidance o o ending oods is he mains ay p e en i e
s a egy o ood alle gy.
2,3
Accu a e diagnosis is essen ial in o de
o p o ide app op ia e, po en ially li e-sa ing ad ice on how o
p e en and manage eac ions. This will also help o p e en
unwa an ed die a y es ic ions.
2,3
The diagnosis o ood alle gy
is ypically based on a combina ion o clinical his o y and an
objec i e ma ke o alle gic sensi isa ion, namely, skin p ick es s
(SPT) and/o immunoassays o se um-specific IgE le els. While
hese app oaches ha e easonable sensi i i y, hey ha e sub-
op imal specifici y and a e in gene al poo ly p edic i e o he
se e i y o eac ions. Fu he diagnos ic confi ma ion wi h a
double-blinded placebo-con olled ood challenge (DBPCFC)— he
gold s anda d diagnos ic es —is he e o e o en equi ed.
2,3,7
DBPCFC is howe e cos ly, echnically challenging, ime-consum-
ing, labou -in ensi e, and associa ed wi h impo an sa e y isks as
he p ocedu e can igge anaphylaxis.
2,3,8
Ne e heless,
al hough isky, DBPCFCs o e a eliable diagnosis, which in u n
inc eases pa ien s’quali y o li e.
9
The limi a ions o con en ional me hods o diagnosing ood
alle gy ha e s imula ed p omising de elopmen s in molecula -
based diagnos ic echniques, collec i ely e e ed o as
componen - esol ed diagnosis (CRD).
2,8,10
Molecula diagnosis
o ood alle gy in ol es examining he specific p o eins in oods,
p ima ily a he molecula le el.
8
In his case, a he han p o iding
a summa y o all he alle gen p o eins in a pa icula ood (e.g.,
peanu s), molecula -based me hods quan i y he indi idual
p o eins wi hin a ood ha may be esponsible o alle gic
eac ions.
8
In CRD, specific IgE esponses a e e alua ed agains
indi idual alle genic molecules o he epi opes o hose alle gens.
The e o e, CRD echniques ha e he po en ial o enhance he
specifici y and sensi i i y o se um-specific IgE esponses o oods.
They may also: acili a e ou abili y o de e mine specific ood
alle gy pheno ypes; help imp o e compila ion o a pa ien - ailo ed
isk p ofile o specific ood alle gens, gi en ha IgE an ibodies
o ood molecules a y om pa ien o pa ien and also
geog aphically; and boos he abili y o dis inguish be ween
p ima y and seconda y sensi ise s.
2,8,10
Impo an ly, in CRD
app oaches, diagnosis can be unde aken ei he in single es
o ma s o in a mic oa ay by simul aneously e alua ing a ange o
alle gens.
2,8,10
The e is now a subs an ial body o e idence on using CRD o
diagnose ood alle gy, which needs o be syn hesised in o de o
gene a e obus es ima es o diagnos ic accu acy and assess cos -
e ec i eness in compa ison wi h con en ional app oaches.
Fu he mo e, a syn hesis o he unde lying e idence will help o
in o m delibe a ions on whe he and how CRD should be
deployed o (i) diagnosing ood alle gy, and (ii) assessing pa ien
isk h ough he p edic ion o ood alle gy se e i y (i.e., he
likelihood o li e- h ea ening anaphylaxis as opposed o ela i ely
mild ea u es) ac oss di e ing heal hca e se ice con ex s.
AIMS
We seek o iden i y, c i ically app aise, and unde ake me a-
analyses o s udies using CRD o he diagnosis o ood alle gy.
Specifically, we aim o:
a. De e mine he accu acy (i.e., sensi i i y, specifici y, posi i e
and nega i e p edic i e alues) o CRD o diagnosis o cow’s
milk, whea , egg, peanu , soy, ee nu s, fish, and shellfish
alle gy.
b. Summa ise he e idence on he cos and cos -e ec i eness o
CRD in compa ison wi h con en ional echniques o he
diagnosis o cow’s milk, whea , egg, peanu , soy, ee nu s,
fish, and shellfish alle gy.
c. Summa ise he e idence on he abili y o CRD o p edic he
se e i y o cow’s milk, whea , egg, peanu , soy, ee nu s, fish,
and shellfish alle gy.
METHODS
The P e e ed Repo ing I ems o Sys ema ic Re iew and Me a-Analysis
P o ocols (PRISMA-P) checklis has been used o guide he epo ing o his
p o ocol.
11
Recei ed: 8 Oc obe 2016 Re ised: 13 Decembe 2016 Accep ed: 20 Decembe 2016
1
As hma UK Cen e o Applied Resea ch, Cen e o Medical In o ma ics, Ushe Ins i u e o Popula ion Heal h Sciences and In o ma ics, The Uni e si y o Edinbu gh, Edinbu gh,
UK;
2
School o Heal h Sciences, Uni e si y o Tampe e, Tampe e, Finland and
3
Edinbu gh Clinical T ials Uni , Cen e o Medical In o ma ics, Ushe Ins i u e o Popula ion Heal h
Sciences and In o ma ics, The Uni e si y o Edinbu gh, Edinbu gh EH8 9AG, UK
Co espondence: Aziz Sheikh (a[email p o ec ed])
www.na u e.com/npjpc m
Published in pa ne ship wi h P ima y Ca e Respi a o y Socie y UK
S udy eligibili y c i e ia
Types o s udies. We will include p ospec i e, e ospec i e, and c oss-
sec ional s udies. S udies mus ha e su ficien da a o calcula e he
ele an diagnos ic measu es, including sensi i i y, specifici y, and posi i e
and nega i e p edic i e alues. All s udies mus ha e a defined s udy
popula ion, wi h ei he consecu i e o andom sampling o pa icipan s. I
he ec ui men echnique used o selec pa icipan s is no indica ed in a
s udy, we will con ac he au ho s o eques u he in o ma ion abou
hei s udy. In he case we do no ecei e a esponse om au ho s, we will
include such s udy and unde ake ele an sensi i i y analyses o assess
hei impac on he o e all es pe o mance.
Types o pa icipan s. We will include s udies ha ha e examined pa ien s
wi h suspec ed ood alle gy o any age.
Ta ge condi ions. We will include s udies examining he CRD diagnos ic
accu acy o alle genic molecules o he eigh mos common IgE-media ed
ood alle gies, namely, cow’s milk, egg, whea , soy, peanu , ee nu s
(including, bu no limi ed o hazelnu , walnu , cashew, b azil nu ,
pis achio, almond), fish (including, bu no limi ed o cod and ca p), and
shellfish (sh imp).
Index es . We will include s udies ha ha e u ilised molecula diagnos ic
echniques ei he based on alle genic molecules (using CRD) o he
epi opes o hose alle gens (using epi ope mapping o p ofiling).
Re e ence s anda d. We will use he DBPCFC as he gold s anda d o
e alua ing es accu acy. We will include s udies in which DBPCFC has
been unde aken in a leas 50% o subjec s in o de o p o ide su ficien
sample o s eng hen he in e nal alidi y o each s udy. Seconda ily, wi h
ega d o e alua ing impac on decision-making, we will also compa e CRD
pe o mance wi h cu en s anda d p ac ice (i.e., clinical assessmen plus
SPT and/o specific IgE).
Exclusion c i e ia. We will exclude he ollowing epo s: e iews,
discussion pape s, non- esea ch le e s and edi o ials; quali a i e s udies;
case s udies, case se ies; animal s udies; and s udies ha include
pa icipan s on he basis o a posi i e ood alle gy es esul .
Sea ch s a egy
We will sea ch he ollowing da abases om 1 Janua y 2000 o 31 July
2016 o s udies o diagnos ic es s o ood alle gy: AMED (O id), CAB
Abs ac s (O id), he Coch ane Lib a y, CINAHL (EBSCO), Embase (O id),
Global Heal h (O id), MEDLINE (O id), PsycINFO (O id), Web o Science
Co e Collec ion (Thomson Reu e s), WHO’s Global Heal h Lib a y, and he
Heal h Economic E alua ions Da abase. Al hough CRD me hods o ood
alle gy we e al eady desc ibed in he 1990s,
12
hei applica ion o ood
alle gy diagnosis came in o o ce ully in he 2000s, hence we ha e chosen
he beginning o 2000 as a easonable s a ing ime o he li e a u e
sea ch. We will ob ain addi ional e e ences by sea ching he e e ences
ci ed in iden ified s udies, by con ac ing in e na ional expe s and au ho s
who ha e published in he field (we ha e compiled a p elimina y lis o
expe s o con ac ), and by sea ching he ISI Con e ence P oceedings
Ci a ion Index. We will sea ch ial egis ies, such as Cu en Con olled
T ials (h p://www.con olled- ials.com), ClinicalT ials.go (h p://www.
clinical ials.go ), he Aus alian and New Zealand Clinical T ials Regis y
(h p://www.anzc .o g.au), and WHO’s In e na ional Clinical T ials Regis y
Pla o m (h p://www.who.in /ic p/en/) o iden i y ongoing s udies. Using
he O id in e ace o MEDLINE, we ha e de eloped a sea ch s a egy
(Appendix 1) o iden i y and e ie e ele an s udies o he e iew and
his will be adap ed in sea ching he o he da abases. The e a e no
language es ic ions o included s udies: li e a u e in languages o he
han English will be ansla ed whe e possible, and any li e a u e ha we
a e unable o ansla e will be epo ed.
Da a managemen and selec ion p ocess
We will expo e ie ed eco ds om all da abases o Endno e Lib a y o
s udy sc eening, de-duplica ion, and managemen o he e ie ed eco ds.
Ti les and abs ac s o e ie ed eco ds will be sc eened and ull ex
copies o po en ially eligible s udies will be assessed by wo independen
e iewe s; a hi d e iewe will a bi a e any disc epancies.
Da a ex ac ion
We will de elop and pilo a da a ex ac ion o m ha will be used o collec
ele an da a om eligible s udies. Two e iewe s will independen ly
ex ac ele an s udy da a om included s udies on o he o m; a hi d
e iewe will a bi a e any disc epancies.
Da a i ems
We will p oduce desc ip i e ables o abula e and summa ise ele an
da a om included s udies. We will cap u e he ollowing minimum se o
da a i ems om included s udies: s udy au ho , coun y o s udy, yea o
publica ion, ype o s udy design, s udy size, sou ce o s udy popula ion,
ype o ood alle gy, ype o CRD used o diagnosed ood alle gy, key
summa y esul s o diagnos ic accu acy, any epo ed isk assessmen
measu es. Fo cos -e ec i eness analyses, he ollowing minimum se o
da a i ems will be ex ac ed: compe ing es s analysed, economic s udy
design ype, economic pe spec i e, es cos , measu ed ou come and i s
alue, and u u e cos s o he ou come and he es . We will use he
PRISMA checklis o guide he epo ing o he sys ema ic e iew.
13
Quali y assessmen o s udies
Risk o bias in eligible s udies will be assessed by wo e iewe s; a hi d
e iewe will a bi a e any disc epancies. We will assess he quali y o
included s udies using he Quali y Assessmen o Diagnos ic Accu acy
S udies (QUADAS-2) ool.
14
We will quali y assess he economic s udies
using he D ummond c i e ia.
15
Fo all s udies, we will quali y assess he
ollowing componen s o each s udy: pa ien popula ion; index es used
and in e p e a ion; ype o e e ence s anda d used; and da a analysis. The
quali y o each o hese componen s will be g aded as high, mode a e, o
low.
Da a syn heses
As a fi s s ep o syn hesising he e idence om included s udies, we will
g aph he diagnos ic es accu acy o he indi idual s udies. The pai ed
esul s o sensi i i y and specifici y will be plo ed as ecei e ope a ing
cha ac e is ic (ROC) cu es, using hese o highligh he co a ia ion
be ween he sensi i i y and specifici y in he indi idual s udies. These
ini ial g aphical ep esen a ions will also enable isual assessmen o he
a ia ion be ween s udies and acili a e subg oup analyses o explo ing
he e ec o ce ain cha ac e is ics (e.g., sex, age, coun y/geog aphical
egion) on es pe o mance. Expec edly, he cu -o s used o define es
posi i i y may a y ac oss s udies; he e o e, o summa ise and compa e
he accu acy o he es ac oss s udies o each endpoin , we will employ
he hie a chical summa y ROC (HSROC) model.
16
Th ough he inclusion o
andom e ec s, he HSROC model accoun s o he a iabili y ac oss
s udies. The model uses s udy-specific es ima es o he ue posi i e a e
(sensi i i y) and he alse posi i e a e (1—specifici y) o es ima e a
summa y ROC cu e. Whe e s udies ha e used a common o simila cu -o
and ha e analysed popula ions wi h simila cha ac e is ics, we will use
pa ame e es ima es om he models o compu e summa y sensi i i ies
and specifici ies wi h 95% confidence in e als. We will in es iga e
be ween-s udy he e ogenei y wi h he HSROC model using he ollowing
co a ia es o e alua e he associa ion be ween s udy ( ype o s udy design,
sampling me hods employed, coun y o o igin, cu -o s o es posi i i y)
and pa ien cha ac e is ics (age, sex, disease se e i y) and es pe o -
mance. The esul s om he quali y assessmen will be used o unde ake
sensi i i y analyses by e alua ing whe he he quali y o s udies (low,
medium, high quali y) has any impac on he o e all conclusion. All
analyses will be pe o med wi h S a a e sion 14.0 (S a aCo p LP, College
S a ion, TX, USA). A na a i e syn hesis o he da a will also be unde aken
and will be he app oach pa icula ly employed in summa ising he
e idence pe aining o isk p edic ion and cos -e ec i eness.
Publica ion bias
We will e alua e publica ion bias by using unnel plo s and Begg and
Egge es s.
17,18
E alua ing confidence in he o e all e idence
We will e alua e he s eng h and quali y o he o e all e idence by using
he GRADE (G ading o Recommenda ions Assessmen , De elopmen and
E alua ion) app oach.
19
The GRADE sys em is use ul o e alua ing he
quali y o e idence and s eng h o ecommenda ions.
19
A e iew p o ocol o ood alle gy
JF Kim e al
2
npj P ima y Ca e Respi a o y Medicine (2017) 10 Published in pa ne ship wi h P ima y Ca e Respi a o y Socie y UK
P o ocol egis a ion
A de ailed p o ocol o he e iew will be egis e ed wi h he In e na ional
P ospec i e Regis e o Sys ema ic Re iews (PROSPERO): h p://www.c d.
yo k.ac.uk/p ospe o/ p io o commencing he e iew.
DISCUSSION
The majo alle gens in di e en ood alle gies ha e now been measu ed
using he CRD echnique ac oss di e en se ings.
8,10,20–23
Fo example,
A a h 2 o peanu alle gy, omega-5-gliadin o whea alle gy, Gly m 4 o
soy milk alle gy, and a numbe o ee nu s, ui s, ege ables, and fish ha e
now been es ablished.
8,10,20–23
Despi e he po en ial o CRD in imp o ing
diagnosis o ood alle gy, a numbe o impo an ques ions ega ding i s
clinical applica ion emain. These include a clea de e mina ion o whe he
hese es s o e benefi o e -and-abo e exis ing p ocedu es and, i so,
whe e in he clinical pa hway CRD fi s—whe he as a sc eening ool o
confi ma o y me hod; an assessmen o he impac o CRD diagnosis on
he isk p ofile o pa ien s; and a clea app ecia ion o he cos implica ions
o i s use in clinical p ac ice in compa ison wi h cu en app oaches.
Add essing hese ques ions will p o ide a s ong basis o deciding on he
significance o CRD o he diagnosis o ood alle gy in he clinical se ing.
This is he fi s sys ema ic e iew o he diagnos ic accu acy o CRD o
ood alle gy: in addi ion o syn hesising he e idence on he diagnos ic
measu es o he eigh mos common ood alle gies (cow’s milk, egg,
whea , soy, peanu , ee nu s, fish, and shellfish), we will, whe e possible,
unde ake isk assessmen o CRD on pa ien s, and summa ise he
es ima es o he cos -e ec i eness o CRD o diagnosing hese ood
alle gies.
ACKNOWLEDGEMENTS
We a e hank ul o Ma shall Dozie , Senio Liaison Lib a ian and Liaison Di ec o o
he College o Medicine and Ve e ina y Medicine a he Uni e si y o Edinbu gh, o
assis ance in de eloping he sea ch s a egy. This wo k is unded by he Chie
Scien is O fice, Edinbu gh (HIPS/16/42). I is pa o J.F.K. disse a ion o he awa d o
MPH deg ee a he Uni e si y o Edinbu gh. B.N. is suppo ed by a ellowship om
he Uni e si y o Tampe e, Finland, wi h addi ional suppo om he Fa Ins i u e
and As hma UK Cen e o Applied Resea ch.
AUTHOR CONTRIBUTIONS
A.S. concei ed he idea o his wo k. I was d a ed by J.F.K. and B.N. and was hen
e ised a e se e al ounds o c i ical commen s om N.M., A.S ., and A.S.
COMPETING INTERESTS
A.S. is Join Edi o -in-Chie o npj P ima y Ca e Respi a o y Medicine, bu was no
in ol ed in he edi o ial e iew o , no he decision o publish, his a icle. The
emaining au ho s decla e no compe ing in e es s.
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A e iew p o ocol o ood alle gy
JF Kim e al
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Published in pa ne ship wi h P ima y Ca e Respi a o y Socie y UK npj P ima y Ca e Respi a o y Medicine (2017) 10