RESEARCH ARTICLE Open Access
E ec i eness o needle and sy inge
P og ammes in people who injec d ugs –
An o e iew o sys ema ic e iews
Rica do M Fe nandes
1,3
, Ma ia Ca y
2
, Gonçalo Dua e
1
, Gonçalo Jesus
1
, Joana Ala cão
1
, Ca la To e
2
, Suze e Cos a
2
,
João Cos a
1,3
and An ónio Vaz Ca nei o
1,3*
Abs ac
Backg ound: Needle and sy inge p og ammes (NSP) a e a c i ical componen o ha m educ ion in e en ions among
people who injec d ugs (PWID). Ou p ima y objec i e was o summa ize he e idence on he e ec i eness o NSP o
PWID in educing blood-bo ne in ec ion ansmission and injec ing isk beha iou s (IRB).
Me hods: We conduc ed an o e iew o sys ema ic e iews ha included PWID (excluding p isons and consump ion
ooms), add essed communi y-based NSP, and p o ided es ima es o he e ec ega ding incidence/p e alence o
Human Immunode iciency Vi us (HIV), Hepa i is C i us (HCV), Hepa i is B i us (HBV) and bac e emia/sepsis, and/o
measu es o IRB. Sys ema ic li e a u e sea ches we e unde aken on ele an da abases, including EMBASE, MEDLINE,
and PsychINFO (up o May 2015). Fo each e iew we iden i ied ele an s udies and ex ac ed da a on me hods, and
indings, including isk o bias and quali y o e idence assessed by e iew au ho s. We e alua ed he isk o bias o each
sys ema ic e iew using he ROBIS ool. We ca ego ized e iews by epo ed ou comes and use o me a-analysis; no
addi ional s a is ical analysis was pe o med.
Resul s: We included hi een sys ema ic e iews wi h 133 ele an unique s udies published be ween 1989 and 2012.
Repo ed ou comes ela ed o HIV (n=9),HCV(n= 8) and IRB (n= 6). Me hods used a ied a all le els o design and
conduc , wi h ou e iews pe o ming me a-analysis. Only wo e iews we e conside ed o ha e low isk o bias using
he ROBIS ool, and mos included s udies we e e alua ed as ha ing low me hodological quali y by e iew au ho s. We
ound ha NSP was e ec i e in educing HIV ansmission and IRB among PWID, while he e we e mixed esul s
ega ding a educ ion o HCV in ec ion. Full ha m educ ion in e en ions p o ided a s uc u al le el and in
mul i-componen p og ammes, as well as high le el o co e age, we e mo e bene icial.
Conclusions: The he e ogenei y and he o e all low quali y o e idence highligh s he need o u u e communi y-le el
s udies o adequa e design o suppo hese esul s.
T ial egis a ion: The p o ocol o his sys ema ic e iew was egis e ed in P ospec i e Regis e o Sys ema ic Re iews
(PROSPERO 2015:CRD42015026145).
Keywo ds: Needle and sy inge p og ammes, Ha m educ ion in e en ions, People who injec d ugs, HIV/Aids-Hc -Hb
* Co espondence: [email p o ec ed]
1
Cen e o E idence-Based Medicine, Facul y o Medicine, Uni e si y o
Lisbonl, A . P o . Egas Moniz, 1649-028 Lisbon, Po ugal
3
Po uguese Collabo a ing Cen e o he Ibe oAme ican Coch ane
Ne wo k-Coch ane Po ugal Facul y o Medicine, Uni e si y o Lisbon, A .
P o . Egas Moniz, 1649-028 Lisbon, Po ugal
Full lis o au ho in o ma ion is a ailable a he end o he a icle
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Fe nandes e al. BMC Public Heal h (2017) 17:309
DOI 10.1186/s12889-017-4210-2
Backg ound
People who injec d ugs (PWID) expe ience high le els o
mo bidi y and mo ali y. D ug- ela ed ha ms include o e -
dose, d ug- ela ed dea hs, and blood-bo ne in ec ions
such as Human Immunode iciency Vi us (HIV), Hepa i is
C (HCV), Hepa i is B (HBV), and bac e emia/sepsis. HCV
is cu en ly he mos p e alen in ec ious disease a ec ing
PWID, while HIV p e alence a es a e lowe . In an es i-
ma ed o al o 12.7 o 16 million PWID wo ldwide, i is
belie ed ha 1.2 million a e in ec ed wi h HIV [1] and 10
million a e in ec ed wi h HCV [2]. Sha ing needles and
sy inges, as well as o he injec ing pa aphe nalia, is a key
ou e o ansmission o hese in ec ions [3].
Needle and sy inge p og ammes (NSP) a e hough o
be a c i ical componen o ha m educ ion in e en ions
among PWID [3, 4]. The i s NSP was es ablished in he
1980s [5], in esponse o he global HIV epidemic, wi h
he goal o p o iding access and encou aging he use o
s e ile injec ion pa aphe nalia by PWID. Since hen,
p o ision o hese se ices has g own apidly. Impo an ly,
a shi in pa adigm has a ou ed NSP as componen s o
ha m educ ion o ha m minimiza ion policies, which
ocus on educing all d ug- ela ed ha ms, i.e. p e en ing
HIV, HBV and HCV in ec ion, minimizing needle and
sy inge sha ing and euse, educing he olume o dis-
ca ded needles and sy inges in he en i onmen , and a-
cili a ing access o s e ile pa aphe nalia. Fu he mo e,
NSP may also p omo e he use o condoms and p o ide
oppo unis ic ele an heal h in o ma ion and se ices [3].
NSP a e complex heal h in e en ions wi h se e al
in e ac ing componen s, such as beha iou al changes in
PWID and p o ide s, a complex ope a ing amewo k
(use s, p o ide s, se ing, heal h sys ems), and some
deg ee o lexibili y o in e en ions [6]. The e is consid-
e able a iabili y among egions and coun ies in se ice
p o ision, co e age and ange o ha m educ ion in e -
en ions o e ed by NSP. In pa icula , a a ie y o
measu es ha e been de eloped o imp o e access o and
use o s e ile injec ing equipmen and o inc ease use s’
choice. These include se e al me hods o dis ibu ion o
sale such as con en ional NSP in ixed-si es, pha macy-
based dis ibu ion, dispensing machines and ou each
p og ammes –o en using a mobile an o bus, o
h ough home- isi s [3]. Gene ally, pha macy and
specialis needle exchange p o ides a wide ange o
ha m educ ion in o ma ion and ad ice, along wi h clean
needles and sy inges and possibly injec ing pa aphe na-
lia. The legal amewo k in which NSP ope a e also
a ies a coun y le el [7]. Pha macy-based NSP a e known
o be in place in a leas Aus alia [8], Belgium, F ance,
I eland, Ky gyzs an, he Ne he lands, Po ugal, Spain,
Slo enia, Uk aine [7, 9], UK [10], and New Zealand [11].
Many sys ema ic e iews on he e ec i eness o in e -
en ions p o iding injec ing equipmen ha e been
conduc ed o da e. O e iews o e iews which compile
in o ma ion om hese mul iple sys ema ic e iews, ha e
also been published. The aim o hese o e iews is o
p o ide end-use s wi h a comp ehensi e and c i ical
summa y o he a ailable e idence on his in e en ion.
O e iews a e o pa icula in e es in his ield because
exis ing sys ema ic e iews ha e ocused on dispa a e
ques ions, ega ding ei he speci ic popula ions (e.g.
coun y-speci ic e idence), speci ic ypes o in e en ions
(e.g. di e en ypes o NSP p o ision) o , mos
commonly, speci ic ou comes (e.g. HIV o HCV ans-
mission) [12–14]. Fu he mo e, he e is a iabili y in
me hods used in hese sys ema ic e iews, including he
assessmen o possible biases and he use o quan i a i e
syn hesis (me a-analysis). Ne e heless, o he bes o
ou knowledge, he published o e iews in his ield
ha e ocused only on speci ic ou comes, i.e. ansmission
o HIV and/o HCV.
Objec i es
Ou p ima y objec i e was o conduc an o e iew o
sys ema ic e iews ha e alua ed he e idence o he
e ec i eness o NSP o PWID ac oss a ange o di e -
en ele an ou comes, i.e. blood-bo ne in ec ion ans-
mission and injec ing isk beha iou s (IRB).
Ou seconda y objec i e was o assess how di e en
aspec s o NSP p o ision, including p o ide , se ing,
co e age and any ela ed componen deli e ed in
pa allel, such as ha m educ ion se ices and opia e
subs i u ion he apy, modi ied he e ec o NSP, wi h a
pa icula ocus on pha macy-d i en NSP.
Me hods
We ollowed cu en guidance on he conduc o
o e iews o e iews, including ecommenda ions om
he Coch ane Collabo a ion [15] and guidance on
public heal h in e en ion e iews by he Cen e o
Re iews and Dissemina ion o he Uni e si y o Yo k
[16]. We also ollowed he ecommenda ions om he
PRISMA-P s a emen ega ding epo ing i ems ha we
conside ed applicable o his o e iew [17]. The p o ocol
o his o e iew was egis e ed a PROSPERO
(CRD42015026145) a ailable a h p://www.c d.yo k.ac.uk/
PROSPERO/display_ eco d.asp?ID=CRD42015026145.
Eligibili y c i e ia
Fo inclusion in his o e iew, s udies had o mee he
ollowing c i e ia:
1. S udy design: sys ema ic e iews, ope a ionally de ined
as s udies epo ing a clea ly s a ed se o objec i es,
eligibili y c i e ia, a sys ema ic sea ch using wo o
mo e sou ces, a sys ema ic p esen a ion o he
cha ac e is ics and indings o he included s udies,
Fe nandes e al. BMC Public Heal h (2017) 17:309 Page 2 o 15
and es ima es o he size and di ec ion o he e ec o
in e en ions p esen ed as nume ical da a, on an
indi idual s udy-le el basis and/o wi h quan i a i e
syn hesis (me a-analysis);
2. Pa icipan s: PWID, de ined as people who injec
some o m o d ug a he beginning o he s udy.
We excluded s udies ocusing exclusi ely on pa icipan s
whose consump ion was con ined o p isons and
consump ion ooms, since hese a e popula ions wi h
dis inc cha ac e is ics om ou a ge popula ion;
3. In e en ions: sys ema ic e iews had o e alua e
communi y-based NSP, de ined as he supply o a
leas needles and sy inges, wi h o wi hou o he
injec ing pa aphe nalia o he p epa a ion and
consump ion o d ugs;
4. Ou comes: equi ed epo ed ou comes included he
incidence and/o p e alence o blood-bo ne in ec ions
(HIV, HCV, HBV and bac e emia/sepsis), and/o
measu es o IRB (including bu no limi ed o sy inge
e-use, bo owing, sha ing, en ing and lending).
When mo e han one e iew included exac ly he same
s udies, he e iew ha epo ed he mos comple e p esen-
a ion o esul s was selec ed o inclusion in he o e iew.
Sea ch s a egy and sc eening
Sea ches we e unde aken on MEDLINE®In-P ocess &
O he Non-Indexed Ci a ions ( om 1946 o 12 h o
May 2015), EMBASE ( om 1974 o 12 h o May 2015)
and PsycINFO ( om 1806 o 12 h o May 2015) ia he
OVID SP in e ace. In addi ion, he ollowing da abases
we e sea ched: he NHS Economic E alua ion Da abase
(NHS EED), he Da abase o Abs ac s o Re iews o
E ec s (DARE), he Coch ane Da abase o Sys ema ic
Re iews (CDSR), he Na ional Ins i u e o Heal h and
Clinical Excellence (NICE), he Campbell Lib a y o
Sys ema ic Re iews and he Da abase o P omo ing Heal h
E ec i eness Re iews (DoPHER). The sea ch s a egies o
each da abase a e shown in a supplemen a y ile
(Addi ional ile 1). No language o o he ypes o es ic-
ions we e applied. In addi ion o he da abase sea ches,
handsea ching o he e e ences o he included e iews
was unde aken o iden i y u he ele an s udies.
Ti les and abs ac s o a icles iden i ied we e sc eened
independen ly by wo au ho s (MC, JA), and classi ied as
include, unclea o exclude. The ull epo s o all
a icles ha classi ied as include o unclea we e hen
ob ained, and wo au ho s (MC, GD) examined compli-
ance o e iews wi h eligibili y c i e ia, wi h a hi d
au ho ac ing as an a bi e (RF).
Da a ex ac ion
Da a om epo s o all included sys ema ic e iews
we e ex ac ed by wo au ho s (MC, GD) and alida ed
by a hi d au ho (RF), using a da a ex ac ion o m
designed and p e-pilo ed o his o e iew. The ollow-
ing gene al cha ac e is ics we e ex ac ed om each
sys ema ic e iew: publica ion de ails; s udy objec i es;
eligibili y c i e ia (popula ion, in e en ion, compa a o s,
ou comes, s udy designs); any epo ed p o ocol; and
me hods used o sea ch, sc eening, da a ex ac ion and
syn hesis. Fo each sys ema ic e iew, we lis ed all in-
cluded s udies and e alua ed whe he hey ma ched he
eligibili y c i e ia o his o e iew ega ding popula ion,
in e en ions and ou comes. We hen ex ac ed he
ollowing esul s om he eligible g oup o s udies,
whene e epo ed a he sys ema ic e iew le el: s udy
design; coun ies in ol ed; cha ac e is ics o included
pa icipan s (demog aphics, p e alence o HIV/HCV);
desc ip ion o in e en ions and any co-in e en ion,
du a ion o in e en ion and ollow-up; e ec es ima es
om me a-analysis (i a ailable) o a indi idual s udy-
le el, o each ele an ou come; and any subg oup o
sensi i i y analyses. The au ho s’conclusions o each
ele an ou come we e also collec ed. We con ac ed he
au ho s o e iews o ele an missing da a.
Assessmen o me hodological quali y
A a s udy le el, we ex ac ed da a on any isk o bias
assessmen s o p ima y s udies when pe o med and e-
po ed by e iewe s in each sys ema ic e iew, including
ools used and summa ized esul s. We also collec ed
da a on any epo ed e alua ions o he quali y o
e idence conce ning ou ou comes o in e es in
included e iews, pa icula ly hose using he G ading o
Recommenda ions Assessmen , De elopmen and E alu-
a ion (GRADE) ool [18], as well as da a on assessmen s
o publica ion bias.
A a sys ema ic e iew le el, we assessed he me hodo-
logical quali y o each included sys ema ic e iew using
he Risk O Bias In Sys ema ic Re iews (ROBIS) ool [19].
Two e iew au ho s (MC, RF) pe o med quali y assess-
men s independen ly, using pilo ed decision ules. Dis-
ag eemen s ega ding o e all assessmen s we e esol ed
h ough discussion, wi h a hi d e iewe se ing as he
inal a bi a o (AVC). The a ionale behind assessmen s
was documen ed. We calcula ed measu es o ag eemen
and eliabili y be ween a e s o each ROBIS domain.
Da a syn hesis
We s a i ied he included sys ema ic e iews by: (i) ype
o ou comes assessed (blood-bo ne in ec ions, IRB), and
(ii) ype o analysis (wi h o wi hou me a-analysis). We
summa ized da a om he included e iews bo h in ex
and in summa y ables and igu es. When me a-analysis
was pe o med, we epo pooled es ima es using he
models and measu es o e ec epo ed by sys ema ic e-
iew au ho s, wi h 95% con idence in e als (95% CI);
Fe nandes e al. BMC Public Heal h (2017) 17:309 Page 3 o 15
we did no pe o m any addi ional s a is ical analysis.
When epo ed, he accompanying I
2
alues, which
desc ibe he pe cen age o o al a ia ion ac oss s udies
ha is due o he e ogenei y a he han chance, we e
collec ed [20].
Resul s
The sea ch and sc eening p ocess is summa ised in
Fig. 1. A o al o 667 ci a ions we e iden i ied h ough
he a ious da abase sea ches. Th ee addi ional e-
co ds we e iden i ied in he e e ence lis s o sc eened
s udies. A e 37 duplica es we e emo ed, we ob ained
633 ci a ions, which we e sc eened by i le and abs ac .
We excluded 582 ci a ions as hey did no mee he inclu-
sion c i e ia, and he emaining 51 we e sc eened ull ex .
Thi y- i e ci a ions we e u he excluded, and wo
epo s [21, 22] we e unob ainable. Fou een epo s
we e hus included, co esponding o 13 sys ema ic
e iews, as wo eco ds e e ed o he same s udy
[12, 23]. Wi hin hose publica ions h ee we e epo s
om Na ional Ins i u es/Expe Commi ees in he US
[24], UK [12] and Canada [25], while 10 we e egula
pape s published in scien i ic jou nals.
Desc ip ion o included e iews
Table 1 lis s he key cha ac e is ics o he 13 included
sys ema ic e iews ha e alua ed he e idence o he
e ec i eness o NSP o PWID in he communi y se -
ing. We classi ied e iews by ype o ou comes epo ed
and ype o da a analysis (Fig. 2).
The numbe o da abases sea ched pe e iew a ied
be ween wo and 15, wi h he h ee mos common
sou ces being MEDLINE, EMBASE and PsycINFO. The
da es o las sea ch a ied be ween 1995 [26] and 2012
[27]. O 287 s udies included in hese 13 e iews, 200
s udies ma ched he eligibili y c i e ia o his o e iew,
co esponding o 133 unique s udies (a ma ix wi h
included s udies by e iew is a ailable in a supplemen-
a y ile: Addi ional ile 2). We included he comple e se
o s udies om ou e iews, as in he emaining e iews a
leas one s udy did no ul ill ou eligibili y c i e ia [27–30].
The numbe o ele an s udies included pe e iew anged
om h ee [31, 32] o 43 [24]. While he e was some
o e lap in he included s udies be ween e iews, he majo -
i y (68%) was included in one e iew only.
We ound subs an ial a iabili y in he c i e ia used by
e iew au ho s o de ine and classi y s udy designs, as well
Fig. 1 Sc eening decisions up o da e as o 30Jun2015. O iginal sea ch da e 12May2015
Fe nandes e al. BMC Public Heal h (2017) 17:309 Page 4 o 15
Table 1 Key cha ac e is ics o he included sys ema ic e iews and Risk o bias o each e iew
Au ho s, da e o
publica ion
a
PICOS
b
Da es o las
sea ch
Da abases sea ched (n) Risk o Bias and quali y o
e idence ools
To al numbe o s udies/
Numbe o s udies ele an
o he o e iew (designs)
c,d
Risk o bias o he
e iew (assessed
using ROBIS ool)
Quan i a i e syn hesis- me a-analysis
Aspinall,
2014 [27]
P: PWID
I: NSP (Specialis si es, pha macies o
ou each se ices)
C: No, a e, o less exposu e o NSP
O: HIV incidence
S: any
2012 CINAHL, Coch ane Lib a y, EMBASE,
IBSS, MEDLINE and PsycINFO (6)
Newcas le-O awa each s udy &
GRADE o assess quali y o
e idence as a whole
12/12 (11 CC/Co; 1 OTH) Low
Hagan, 2011 [34] P: indi iduals who could concei ably
ha e acqui ed HCV in ec ion ia
adminis a ion o an illegal d ug (PWID
among hem)
I: in e en ions ha could p e en HCV
in ec ion
C:NR
O: HCV p e alence o incidence a es,
and measu es o associa ion wi h
p e alence o incidence
S: any
2010 Cu en Con en s, Disse a ion
Abs ac s, ERIC, NIH CRISP, MEDLINE,
PsycINFO, Sociological Abs ac s (7)
De eloped hei own quali y
scale
26/7 (7 CC/Co) High
Tu ne , 2011 [32] P: PWID in he UK
I: NSP o OST (o combina ion)
C: OST s non OST; high s low
co e age o NSP
O: HCV in ec ion and IRB
S: any
NR PubMed and Web o Science (2) None 4/3 (1 CC/Co; 2 OTH) High
C oss, 1998 [26] P: PWID
I: NSP o educa ional p og ammes
C: NR
O: IRB
S: expe imen al o quasi-expe imen al
design
1995 AIDSLINE, MEDLINE, PsycINFO, Social
Science Ci a ion Index (4)
None 26/10 (1 RCT; 9 OTH) High
Quali a i e syn hesis
Abdul-Quade ,
2013 [29]
P: PWID
I: S uc u al in e en ions ha add ess
ex e nal ac o s o educe HIV and HCV
C: any quan i a i e compa ison
O: Changes in HIV/HCV in ela ion o
in e en ion
S: con olled o be o e & a e
2011 Coch ane Cen al Regis e o
Con olled T ials, EMBASE, LILACS,
PsycINFO, PubMed, and he Web
o Science/Web o Social
Science (6)
WHO-Johns Hopkins 9-Poin
Rigou Scale.
15/15 (1 CC/Co; 14 OTH) Unclea
Des Ja lais, 2013 [28] P: PWID in low-and middle income
and ansi ional coun ies (LMICs)
I: NSP
C: any
O: changes in p e alence o incidence
o HIV, HCV, HIV/ HCV co-in ec ion o
changes o e ime in newly epo ed
HIV o HCV cases o in ec ion
S: any
2011 EMBASE, NLM Ga eway, PubMed,
Web o Science (4)
None 13/13 (13 OTH) High
Fe nandes e al. BMC Public Heal h (2017) 17:309 Page 5 o 15

Table 1 Key cha ac e is ics o he included sys ema ic e iews and Risk o bias o each e iew (Con inued)
Hong and Li,
2009 [31]
P: People wi h HIV/ AIDS in China
I: Any beha iou al in e en ion
C: Any
O: Ra e o needle-sha ing
S: Any
2008 AIDSLine, EBSCO, Fi s Sea ch,
PsycINFO, PubMed (4)
None 25/3 (1 RCT; 1 CC/Co; 1
OTH)
High
Jones, 2008 [12] P: PWID
I: NSP
C: any
O: IRB, HIV, HVC
S: RCT, con olled non- andomised
s udies, con olled and uncon olled
be o e and a e s udies, c oss-sec ional
s udies, coho s udies, case-con ol
s udies and ecological s udies
2008 ACP Jou nal Club, ASSIA, CINAHL,
Coch ane Lib a y,
EMBASE, EPPI-Cen e da abases,
Heal h In o ma ion Managemen
Conso ium, IBSS, MEDLINE,
Na ional Resea ch Regis e
A chi e, OpenSIGLE, P ojec CORK,
PsycINFO,
Sociological Abs ac s,
SOMED (15)
Quali y assessmen ools
de eloped by NICE Cen e o
Public Heal h Excellence, England
and Wales and he E ec i e Public
Heal h P ac ice P ojec , Canada
24/15 (2 RCT; 1 CC/Co; 12
OTH)
Low
Kall, 2007 [30] P: PWID
I: NSPs
C: con ol o compa ison g oups
O: HIV incidence o p e alence
S: any
2005 MEDLINE and PsyclNFO (2) None 16/16 (8 CC/Co; 8 OTH) High
W igh , 2006 [33] P: PWID
I: p ima y p e en ion in e en ion
a ge ing injec ing d ug use
C: any
O: HCV p e alence and incidence
S: in e en ion o obse a ional s udies
2003 Coch ane Lib a y, CINAHL,
EMBASE, MEDLINE and PsycINFO (4)
De eloped hei own quali y scale 18/12 (9 CC/Co; 3 OTH) High
Tilson, 2006 [24] P: PWID
I: NSP
C: Wi h and wi hou OST; Placebo.
O: IRB, HCV and HIV
S: NR
2006 Coch ane Lib a y, G ey Li e a u e
Repo , EMBASE, PubMed,
PsycINFO, Social Science
Abs ac s, Web o Science,
Wo ldCa (8)
GRADE 45/43 (28 CC/Co; 15 OTH) Unclea
Gibson, 2001 [35] P:PWID
I:NSP
C: any
O:HIV, HBV, HCV and IRB
S:any
1999 Medline and PsycINFO (2) None 42/32 (19 CC/Co; 13 OTH) High
Leona d, 1999 [25] P: PWID
I: NSP
C: Any compa a o g oup (bu none
was no allowed)
O: HIV, HCV and IRB
S: NR
1999 AIDSLINE, CINAHL, Coch ane
Lib a y, EMBASE, MEDLINE,
PHE ec (6)
Quali y assessmen ools de eloped
by he E ec i e Public Heal h P ac ice
P ojec eam, Canada
21/19 (15 CC/Co; 4 OTH) Unclea
a
Ca ego ized by ype o syn hesis and lis ed by publica ion da e
b
PICOS: ac onym o Popula ion, In e en ion, Compa a o , Ou come and S udy Design
c
Classi ied by au ho s o he e iew
d
CC/Co: Case-Con ol/Coho ; RCT: Randomized Con ol T ial; OTH: o he ( ime-se ies designs, be o e-a e s udies, ecological s udies)
Fe nandes e al. BMC Public Heal h (2017) 17:309 Page 6 o 15
as ypes o designs o included s udies. Only ou e iews
speci ied he ypes o s udy design in hei eligibili y
c i e ia [12, 26, 29, 33]. Th ee e iews included andom-
ized con olled ials ( ou RCTs o e all) [12, 26, 31], while
he emaining e iews included coho s and case-con ols
(101 o e all), as well as o he s udy designs ( ime se ies,
be o e/a e s udies o ecological s udies) (95 o e all).
Th ee o he included e iews we e es ic ed o
s udies conduc ed in speci ic coun ies o economic e-
gions (China, UK, and low- and middle-income coun ies)
[28, 31, 32]. Nine e iews epo ed da a on HIV, eigh on
HCV, and six on IRB. Se en e iews e alua ed mo e han
one o hese ou comes. Fou e iews used me a-analysis
[26, 27, 32, 34], one o which using indi idual-pa icipan
da a [32]. The emaining nine e iews used na a i e
syn hesis [12, 24, 25, 28–31, 33, 35]. The easons epo ed
by he au ho s o conduc ing o no conduc ing
me a-analysis a ied be ween e iews, e en when he e
was a deg ee o o e lap be ween included s udies.
Me hodological quali y
Se en e iews epo ed ha ing assessed he me hodo-
logical quali y o included s udies [12, 24, 25, 27, 29, 33, 34].
In wo e iews he au ho s de eloped ad hoc ools [33, 34],
while he emaining e iews used p e iously exis ing
ins umen s, o en wi h modi ica ions ( ools used:
Newcas le-O awa, GRADE, WHO-Johns Hopkins 9-
Poin Rigou Scale, Quali y assessmen ools de el-
oped by NICE Cen e o Public Heal h Excellence,
England and Wales and he E ec i e Public Heal h
P ac ice P ojec , Canada) [12, 24, 25, 27, 29]. Only
wo ins umen s we e used mo e han once, and all
o he ins umen s a ied. No all e iews epo ed he
esul s o hese assessmen s; when epo ed, mos
s udies we e conside ed o ha e low me hodological
quali y, gi en me hodological weaknesses and biases
ela ed o obse a ional s udy designs. Only one
quan i a i e e iew [27] inco po a ed quali y in da a
syn hesis, by conduc ing a sensi i i y analysis. In
e iews wi hou me a-analysis, me hodological quali y
and isk o bias was p esen ed desc ip i ely in he
in e p e a ion o s udy esul s. Two e iews [24, 27]
epo ed using he GRADE ool o assess he quali y
o he body o e idence. One conside ed he o e all
quali yo e idenceaslow[27],while heo he ,using
an adap a ion o GRADE, e alua ed he quali y o
Fig. 2 S udies selec ed o inclusion classi ied by ou come(s) epo ed and s a egy o da a syn hesis. *G ey shaded boxes ep esen he ou come
epo ed in he e iews indica ed in he igh column. “HIV”,”HCV”and “Injec ing isk beha iou s”is used o classi y he e iews ha epo ed he
impac o NSP in he numbe o HIV in ec ions, numbe o HCV in ec ions and change in injec ion beha io . The e iews a e also p esen ed in he
igh column by s a egy used o da a syn hesis
Fe nandes e al. BMC Public Heal h (2017) 17:309 Page 7 o 15
e idence as modes o mode a e o di e en ou -
comes [24].
Using he ROBIS ool, only wo o he included e iews
we e conside ed o ha e low isk o bias, whe eas he
emaining we e conside ed o ha e ei he high (n=8)o
unclea isk o bias (n= 3) (summa y o esul s a ailable in
a supplemen a y ile: Addi ional ile 3). The majo i y o e-
iews we e a ed as ha ing high o unclea isk o bias
ac oss all ROBIS domains, i.e. s udy eligibili y c i e ia, iden-
i ica ion and selec ion o s udies, da a collec ion and s udy
app aisal, syn hesis and indings. Pe cen age o ag eemen
be ween ROBIS a e s a ied be ween 77% and 92%, and
weigh ed kappa (quad a ic) be ween 0.82 and 0.95.
The esul s om he PRISMA-P s a emen applied o
his o e iew a e p esen ed a Addi ional ile 4.
E ec s o NSP
HIV p e alence and/o incidence
O nine e iews ha epo ed da a on HIV ou comes,
wo we e a low isk o bias [12, 27], and only one
pe o med me a-analysis [27]. The p opo ion o s udies
included in only one o hese nine e iews was 71%.
Re iews wi h me a-analysis The mos ecen e iew by
Aspinall e al. included wel e s udies (10 coho , one
case-con ol and one c oss-sec ional s udy), and was
e alua ed as ha ing low isk o bias. The e iew epo ed
a 34% “ isk” educ ion o HIV ansmission (pooled
e ec es ima e o 0.66; 95% CI: 0.43 o 1.01; n=10
s udies; I
2
= 76%) in indi iduals exposed o NSP, com-
pa ed wi h hose who we e no , o we e less equen ly,
exposed o NSP. This es ima e was ob ained by pooling
bo h adjus ed and unadjus ed e ec sizes ega dless o
s udy design, in a andom e ec s model, and pooling all
ypes o e ec measu es (odds a io, isk a io, haza d
a io). Sensi i i y analyses suppo ed hese esul s, wi h a
s a is ically signi ican educ ion in HIV ansmission
associa ed wi h NSP exposu e in bo h highe quali y s ud-
ies (0.42; 95% CI: 0.22 o 0.81), and s udies epo ing ela-
i e isks o haza d a ios (0.60; 95% CI: 0.37 o 0.97).
Subg oup analyses showed ha s udies using sequen ial
ollow-up (i.e. g oups exposed o NSP and g oups no ex-
posed ollowed sequen ially, and no concu en ly) and
s udies ec ui ing pos -1990 had lowe e ec es ima es
(0.21 [95% CI: 0.11 o 0.41] and 0.52 [95% CI: 0.28 o
0.95], espec i ely). Fu he , s udies compa ing 100% NSP
co e age (i.e. clean needle and sy inge used o 100% o
injec ions) wi h <100% NSP co e age gene a ed a pooled
e ec es ima e o 0.58 (95% CI: 0.22 o 1.57). Quali y o
e idence was conside ed low using GRADE, and mos o
hese esul s had subs an ial he e ogenei y.
Re iews wi hou me a-analysis The quan i a i e esul s
p esen ed abo e a e suppo ed by mos e iews wi h
quali a i e summa ies o he e idence only, all o which
published be ween 1999 and 2013. Di e ences be ween
e iews could be ound ega ding eligibili y c i e ia (e.g.
ype o NSP, popula ion- s indi idual-le el ou comes,
s udy design), sea ch and sc eening me hods, quali y
assessmen s and in e p e a ion o s udy esul s. In mos
o hese e iews, he au ho s desc ibed and con ex ual-
ized esul s om each indi idual s udy o g oup o
s udies ega ding HIV ou comes. Some e iews used
o e coun ing o compa e he numbe o posi i e s udies
wi h educ ion in HIV ansmission, wi h he numbe o
nega i e s udies. In he ollowing pa ag aphs, we p esen
he main esul s o hese e iews, s a ing wi h hose
ocusing on he impac o di e en aspec s o NSP
p o ision ollowed by esul s o e iews ocusing exclu-
si ely on he compa ison be ween NSP andno NSP.
Rega ding aspec s o NSP p o ision, Jones and
colleagues epo ed esul s om a ecen sys ema ic e-
iew classi ied as low isk o bias, ha ocused on le el
o co e age, sy inge dispensa ion policies, ype o NSP,
p o ision o addi ional ha m- educ ion se ices and o
opia e subs i u ion he apy [12]. Au ho s judged ha he
ange o s udy designs, in e en ion app oaches exam-
ined and ou comes p ecluded he use o me a-analysis.
Only h ee s udies ocused on HIV ou comes. A low-qu-
ali y s udy showed no signi ican end o HIV p e a-
lence when compa ing p ima y sou ces o needles
(pha macies, ixed si e NSP and an-based NSP),
al hough HIV p e alence was lowe among pha macy
use s han in pa icipan s who epo ed using an o
ixed si e NSP (16% s. 21% and 25%, espec i ely,
p= 0.16) [36]. Ano he s udy [37] included in his
e iew examined he impac o dispensa ion policies,
and no ed a dec ease in HIV p e alence (based on es -
ing o sel - epo ) be ween he pe iod o legal pha macy
sy inge pu chase and when up o i e needles could be
exchanged a newly es ablished NSP (35% o 22%;
p< 0.05). Finally, one mode a e quali y coho s udy
[38] also included in he e iew by Jones and colleagues
e alua ed di e en le els o ha m educ ion and ound
ha a ull ha m educ ion s a egy (combina ion o
me hadone ea men and ull pa icipa ion in NSP)
educed he incidence o HIV when compa ed o incom-
ple e o no ha m educ ion (incidence a e a io: 0.32;
95% CI: 0.17 o 0.62).
In line wi h hese esul s, a e iew wi h an o e all
unclea isk o bias by Abdul-Quade e al. [29] iden i-
ied s udies wi h s uc u al-le el NSP, ie in e en ions in
which changes in policy and legal en i onmen ha e
acili a ed an inc eased a ailabili y o s e ile sy inges,
and ocused on popula ion-le el ou comes. The ope -
a ional de ini ion o s uc u al-le el NSP was a
minimum 50% co e age o PWID and dis ibu ion o 10
o mo e needles/sy inge pe PWID pe yea . Nine s udies
Fe nandes e al. BMC Public Heal h (2017) 17:309 Page 8 o 15
included in his e iew epo ed dec eases in HIV p e a-
lence, and h ee epo ed dec eases in HIV incidence. All
s udies we e non- andomized be o e-a e compa isons o
in e up ed ime se ies analyses, and mos showed
e idence o po en ial selec ion biases. The au ho s con-
cluded ha hese esul s suppo NSP as a s uc u al-le el
in e en ion o educe popula ion-le el in ec ion.
Fou olde published e iews wi h quali a i e syn hesis
and an o e all unclea o high isk o bias epo ed
mixed indings ega ding he impac o NSP on HIV in-
cidence/p e alence. These e iews p o ide a his o ical
pe spec i e on he e olu ion o NSP implemen a ion
and e alua ion. The i s published e iew by Leona d
e al. [25], was an upda e o a p e ious sys ema ic
e iew. Gibson e al. [35] included six s udies published
up o 1999 wi h a ange o s udy designs, pa icipan s
and se ings, epo ing on HIV ou comes. The Ins i u e
o Medicine’s e idence epo [24], iden i ied 12 ele an
s udies, including coho , case-con ol and ecological
designs, as well as s udies using ma hema ical models.
Finally, he e iew by Kall e al. [30] included 16 s udies
published up o 2005, only wo o which we e no
included in o he e iews om his o e iew.
All hese e iews included landma k p ospec i e
coho s udies conduc ed in Mon eal and Vancou e in
he 1990s [39, 40], which ound an associa ion be ween
NSP pa icipa ion and highe isk o HIV se ocon e -
sion. This led Leona d e al. o conclude ha he e was
me hodologically weak e idence ha NSP we e no as
e ec i e as p e iously ound in modi ying HIV p e a-
lence and incidence among PWID. Kall e al. used o e
coun ing and epo ed ha on mos s udies assessing
se oincidence he e ec o NSP was no signi ican ,
while ou s udies in es iga ing se op e alence a base-
line we e un a ou able o NSP. The au ho s also s a ed
ha in s udies ha ound posi i e e ec s, con ounde s
had no been adequa ely con olled o . Howe e , based
on epidemiological e idence ha accumula ed p og es-
si ely, au ho s o he o he e iews highligh ed a
numbe o selec ion biases ha could accoun o
hese indings, including: he inclusion o high- isk
cocaine injec o s, who injec ed mo e o en han
he oin use s; he limi ed numbe o needles and sy-
inges ha use s could ha e access o in ea ly NSP;
and he eady a ailabili y o clean injec ing equipmen
h ough pha macies which could ha e a ac ed
ma ginalized, pa icula ly high- isk indi iduals.
Follow-up s udies in he same se ings, conduc ed a e
expanding and adjus ing NSP (e.g. by allowing unlimi ed
dis ibu ion o needles/sy inges, inc easing he numbe o
access poin s, and o e ing di e en dis ibu ion me hods),
ound no such inc ease in isk, o a dec ease in HIV
p e alence. Gibson e al. [35] used o e coun ing and con-
side ed he e was subs an ial e idence ha NSP we e
e ec i e in p e en ing HIV se ocon e sion. Tilson e al.
[24] included ou ecological s udies ha ound an associ-
a ion be ween HIV p e en ion p og ammes ha include
NSP wi h educed p e alence o HIV in u ban se ings.
Based on he weakness o hese s udies designs, his e i-
dence was conside ed modes using a modi ied GRADE
app oach. Fu he , mode a e e idence was ound ha
mul i-componen HIV p e en ion p og ammes ha in-
clude NSP educe in e media e HIV isk beha iou .
The Ins i u e o Medicine epo highligh ed how almos
all published s udies o igina e in No h Ame ica, Wes e n
Eu ope, and Aus alia [24]. Two addi ional e iews we e
es ic ed o speci ic popula ions by geog aphical o
economical sou ce. Hong and Li summa ized e idence
om wo s udies conduc ed solely in China [31], while
Des Ja lais e al. ocused on 13 s udies o 11 NSPs wi h
high-co e age conduc ed in low/middle-income coun ies
[28]. In bo h cases, esul s om included s udies gene ally
suppo ed he e ec i eness o NSP in educing HIV. Des
Ja lais e al. epo ed a educ ion o HIV p e alence in
ou s udies ( om −3% o −15%), o es ima ed HIV inci-
dence in h ee s udies ( om −11/100 o −16/100 pe son-
yea s a isk), and o newly epo ed na ionwide cases in
h ee na ional epo s ( om −30% o −93.3%). Con e sely,
inc eases in HIV p e alence we e ound in wo s udies
( om +5.6% o +15.8%) and one na ional epo (+37.6%)
included in he e iew by Des Ja lais e al. The au ho s
conside ed ha , i high co e age is achie ed, NSP appea
o be as e ec i e in low/middle-income as in high-income
coun ies [28].
HCV p e alence and/o incidence
Eigh included e iews syn hesized he e idence on he
use o NSP in p e en ing HCV p e en ion in PWID. One
was a ed as being a low [12], h ee a unclea [24, 25, 29]
and ou a high isk o bias [28, 32–34], including wo
e iews ha used me a-analysis [32, 34]. The p opo ion
o s udies included exclusi ely in one o hese e iews was
88%. Bo h e iews wi h quan i a i e and quali a i e
syn hesis showed mixed esul s.
Re iews wi h me a-analysis Two e iews [32, 34], bo h
published in 2011 and a ed as being a high isk o bias,
used me a-analysis.
Hagan e al. [34] included 7 s udies ocusing on NSP
and HCV ou comes (6 coho and 1 case-con ol s udy),
all om No h Ame ica. The pooled analysis o all s udies,
using andom e ec s models and wi h all measu es o
e ec con e ed o ela i e isks, showed an inc ease in
he isk o HCV acquisi ion wi h NSP ( ela i e isk, 1.62;
95% CI: 1.04 o 2.52). The e was conside able he e ogen-
ei y (I
2
= 81%), bu no subg oup o sensi i i y analyses
we e pe o med, and s udy quali y was no explici ly
epo ed o conside ed in he analysis. Au ho s cau ioned
Fe nandes e al. BMC Public Heal h (2017) 17:309 Page 9 o 15