RESEARCH ARTICLE
Loo box engagemen : A scoping e iew o
p ima y s udies on p e alence and
associa ion wi h p oblema ic gaming and
gambling
I ene Mon iel
1☯
, A a
´nzazu Bas e a-Gonza
´lez
1☯
, Juan M. Machimba ena
2
, Je
´ssica O ega-
Ba o
´nID
1
, Joaquı
´n Gonza
´lez-Cab e aID
1
*
1Facul y o Educa ion, Uni e sidad In e nacional de La Rioja (UNIR), Log oño, La Rioja, Spain, 2Facul y o
Psychology, Uni e sidad del Paı
´s Vasco (UPV/EHU), Donos ia, Basque Coun y, Spain
☯These au ho s con ibu ed equally o his wo k.
*joaquin.gonzalez@uni .ne
Abs ac
Backg ound
Loo boxes a e an inc easingly common ype o andom mic o ansac ion in ideogames.
The e is some conce n abou hei expansion and en ailed isks, especially among adoles-
cen s. The ac ual p e alence o engagemen wi h loo boxes among child and adul popula-
ion is unce ain, and he e is s ill con o e sy o e he na u e o hei ela ionship wi h
p oblema ic gaming and gambling.
Objec i es
The aims o his scoping e iew a e o summa ize he cha ac e is ics and indings o pub-
lished p ima y empi ical s udies abou he p e alence o engagemen wi h loo boxes and/o
hei ela ionship wi h p oblema ic gaming and gambling, aking in accoun he ype o sam-
ple, ime ame and measu ed a iables.
Me hods
This s udy ollows he Joanna B iggs Ins i u e’s “Guidance o conduc ing sys ema ic scop-
ing e iews” and he P e e ed Repo ing I ems o Sys ema ic e iews and Me a-Analyses
ex ension o Scoping Re iews (PRISMA-ScR). Th ee academic da abases p o ided 299
a icles.
Resul s
Six een p ima y empi ical s udies me he inclusion c i e ia o his e iew. All s udies used
c oss-sec ional designs, and mos used con enience samples. Twel e s udy samples we e
comp ised exclusi ely o game s, and wo we e comp ised o game s and/o gamble s.
Only six s udies included adolescen s. The annual p e alence a e o loo box pu chases
was highe o adul game s han o adolescen s (22.7%–44.2% and 20%–33.9%,
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OPEN ACCESS
Ci a ion: Mon iel I, Bas e a-Gonza
´lez A,
Machimba ena JM, O ega-Ba o
´n J, Gonza
´lez-
Cab e a J (2022) Loo box engagemen : A scoping
e iew o p ima y s udies on p e alence and
associa ion wi h p oblema ic gaming and
gambling. PLoS ONE 17(1): e0263177. h ps://doi.
o g/10.1371/jou nal.pone.0263177
Edi o : Ma c Po enza, Yale Uni e si y, UNITED
STATES
Recei ed: May 24, 2021
Accep ed: Janua y 13, 2022
Published: Janua y 27, 2022
Copy igh : ©2022 Mon iel e al. This is an open
access a icle dis ibu ed unde he e ms o he
C ea i e Commons A ibu ion License, which
pe mi s un es ic ed use, dis ibu ion, and
ep oduc ion in any medium, p o ided he o iginal
au ho and sou ce a e c edi ed.
Da a A ailabili y S a emen : All ele an da a a e
wi hin he manusc ip and i s Suppo ing
in o ma ion iles.
Funding: This esea ch was unded by he Spanish
Minis y o Economy, Indus y and
Compe i i eness, RTI2018-094212-B-I00: (CIBER-
AACC), and by he In e na ional Uni e si y o La
Rioja, P ojec "Cybe psychology" (2017-2020) and
P ojec "DOMIN-US" (2020-2022). The e was no
addi ional ex e nal unding ecei ed o his s udy.
espec i ely), bu in s udies wi h gene al popula ion samples, he opposi e was ue (24.9%
o playe s aged 13–14 e sus 7.8% o adul s). In gene al, he s udies sugges ed a signi i-
can posi i e ela ionship be ween engagemen wi h loo boxes and p oblema ic gaming and
gambling, bu his may be ela ed o he ype o engagemen (open/pu chase/sell), and he
cha ac e is ics o he s udy pa icipan s (male/ emale, adolescen s/adul s, game s/game s-
gamble s/gene al popula ion).
Conclusions
This scoping e iew summa izes he esul s o ecen empi ical s udies on engagemen wi h
loo boxes and discusses how me hodological issues may a ec hei esul s and in e p e a-
ion. Recommenda ions o u u e esea ch a e also p o ided.
In oduc ion
Almos 40% o he wo ld’s popula ion plays ideogames [1]. The numbe o game s has
inc eased by an a e age o 6% pe yea o e he pas i e yea s, eaching 2.7 billion use s by
2020. Re enue in he ideogame indus y eached $120.1 billion in 2019 and app oxima ely
$159.3 billion in 2020, an annual inc ease o mo e han 9% [1]. An impo an sou ce o e e-
nue—and one componen o his indus y’s success—lies in he inco po a ion o in-game pu -
chases [2,3].
Wi hin a ideogame, he e a e se e al objec s (usually di e en in each ideogame) ha
allow playe s o gain in-game imp o emen s and ad an ages and quickly achie e he game’s
objec i es. G aphic elemen s ha modi y he ex e nal appea ance o he cha ac e s by chang-
ing hei aes he ics, hei clo hes, o hei weapons (so-called skins) a e also common. These
ad an ages a e usually pu chased h ough mic o ansac ions (i.e., a playe pays a s ipula ed
p ice o a speci ic and known ad an age o skin) [4]. Loo boxes, also called c a es, gachas,
cases, o ches s, a e one speci ic ype o mic o ansac ion in which a andom i ual i em is
pu chased [5,6]. Loo boxes can be pu chased using eal o i ual in-game money, wi h he
mos desi ed i ems appea ing less equen ly [7,8].
The mos es ablished games in he wo ld (e.g., O e wa ch, FIFA, Ba le ield, Call o Du y,
Fo ni e, and League o Legends) include loo boxes wi hin hei mechanics. The p esence o
loo boxes in desk op ideogames inc eased 67% be ween 2010 and 2019 [9], and mo e han
58% o Google Play and iPhone games con ain loo boxes [10]. Among game s, 78% o adul s
ha e pu chased a leas one loo box [11], and 40.5% o adolescen s be ween he ages o 16 and
18 ha e pu chased one wi hin he pas mon h [12]. One o he mos wo isome aspec s is ha
56% o mobile games con aining loo boxes a e conside ed sui able o child en aged 7 yea s
o olde , and 93% a e conside ed sui able o child en a leas wel e yea s o age [10]. The e is
some e idence abou he inc easing use o loo boxes, bu he eal ex en o he phenomenon is
s ill unce ain, as a e he isks i migh en ail o bo h adul s and adolescen s.
Some au ho s claim ha loo boxes in oduce gambling elemen s in o gaming and a gue
ha hey may ac as a ga eway o p oblema ic gambling o ha hey could agg a a e gambling
o gaming- ela ed ha m [5–7,13]. Whe he he excessi e use o loo boxes is bes concep ual-
ized unde he heo e ical amewo k o p oblem gambling o p oblem/excessi e gaming is
also unde deba e [4,13,14]. A ecen me a-analysis ound a small bu po en ially clinically el-
e an ela ionship be ween gambling symp oma ology and loo box spending. I was also
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The unde s had no ole in s udy design, da a
collec ion and analysis, decision o publish, o
p epa a ion o he manusc ip .
Compe ing in e es s: The au ho s ha e decla ed
ha no compe ing in e es s exis .
shown ha his associa ion was a leas as la ge as ha ound be ween excessi e gaming symp-
oms and loo box spending, sugges ing he need o u he esea ch [14]. Some longi udinal
s udies ha e also poin ed ou ha p oblema ic gaming appea s o be an en y beha io o p ob-
lema ic gambling [15]. Howe e , a ecen e iew ound li le con incing e idence in suppo
o his “ga eway hypo hesis,” sugges ing ha u he longi udinal esea ch is needed o be e
unde s and he links be ween ideo gaming and gambling [13].
In ligh o he abo e and wi h he p ima y pu pose o p o ec ing child en and adolescen s, a
legisla i e deba e has been ini ia ed abou whe he engaging wi h loo boxes should be consid-
e ed “gambling.” Some au ho s emphasize i s i ual, unce ain, and andom na u e, poin ing
o a ela ionship wi h he ewa d sys ems p esen in gambling [16,17]. O he s claim ha loo
boxes a e a clea hyb id be ween slo machines and collec ible ca d packs [18] and simply ha e
simila i ies wi h gambling beha io s [19]. Nielsen and G aba czyk [20] a gue ha loo boxes
a e a speci ic applica ion o a mo e gene al phenomenon called he andom ein o cemen
mechanism, which has been implemen ed in ideogames o decades [17]. These ewa d
mechanisms a e also p esen in slo machines, and hei componen s a e a condi ion o eligi-
bili y (a equi emen ha he playe mus mee o ac i a e he ewa d, such as eaching a ce -
ain numbe o poin s), andomness (e.g., shu ling o h owing dice), and ewa d (e.g., a new
weapon) [20]. These au ho s a gue ha only hose ha a e embedded in he b oade economy
(i.e., hose ha o e andomized ewa ds ha can be bo h sold and pu chased) can be consid-
e ed s uc u ally simila o gambling. Howe e , as demons a ed by D ummond e al. [21], i -
ual i ems ha e eal-wo ld mone a y alue o use s, i espec i e o whe he hey can be cashed
ou ; he e o e, hey could be egula ed unde exis ing gambling legisla ion. The ela ionship
be ween loo boxes and andom ewa d mechanisms aises conce ns o adolescen s and
young people, as hese popula ions a e mo e ulne able o de eloping emo ional, cogni i e,
and beha io al p oblems ela ed o adi ional and online gambling [22–25]. Fu he mo e,
hese popula ions may no ully unde s and he associa ed unde lying mechanisms and ewa d
sys ems [2,26]. This makes he issue o loo boxes and hei po en ial simila i ies o gambling
o pa icula in e es when i comes o p o ec ing child en and young people, o he same ea-
son ha hese popula ions a e p ohibi ed om gambling.
The disc epancies in he scien i ic li e a u e men ioned abo e can be e lec ed in he di e -
en s ances ha coun ies ake ega ding loo box egula ion. Fo example, Belgium and he
Ne he lands conside loo boxes o be an illegal o m o gambling [27]. In he USA he e is no
uni o m legisla ion ega ding his opic [28] and he Uni ed Kingdom ha e p ohibi ed he use
o loo boxes only i hei con en s can be sold ou side o he ideogame i sel [29]. O he coun-
ies, such as China and Sou h Ko ea, equi e game de elope s o disclose he odds o winning
he p ize [30]. Japan only p ohibi s some ypes o loo boxes, such as he “kompu gacha”
(boxes wi h a e ewa ds ha can only be unlocked a e pu chasing a collec ion o o he loo
box i ems) [31]. Clea ly, i is necessa y o ad ance and homogenize scien i ic/ echnical c i e ia
o help policymake s s anda dize such impo an poli ical and legal guidelines.
Due o he eme ging na u e o his ield, a scoping e iew is he mos app op ia e me hodo-
logical app oach o assessing and unde s anding ou esea ch ques ions. Scoping e iews a e
pa icula ly use ul when a body o li e a u e has no ye been comp ehensi ely e iewed o
exhibi s a complex o he e ogeneous na u e [32]. Mo eo e , scoping e iews allow us o iden-
i y u he a eas o subsequen esea ch and cla i y whe he a sys ema ic e iew may be con-
duc ed o add ess mo e speci ic ques ions [33]. Two sys ema ic e iews abou loo boxes ha e
ecen ly been published [14,34], bu hey ocused exclusi ely on he ela ionship be ween loo -
box- ela ed spending and p oblem gaming and/o gambling. These e iews did no summa ize
he p e alence o engagemen wi h loo boxes o p o ide sepa a e da a o adolescen s e sus
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adul s. Addi ionally, many empi ical s udies ha did no appea in hese wo ks ha e ecen ly
been published in pee - e iewed jou nals.
The e o e, we conduc ed a scoping e iew o he p ima y empi ical s udies on engagemen
wi h loo boxes published o da e in pee - e iewed jou nals. Ou ini ial esea ch ques ions
we e as ollows: 1) How did hese p ima y empi ical s udies measu e engagemen wi h loo
boxes? 2) Wha is he p e alence o engagemen wi h loo boxes among adul s and adoles-
cen s? 3) Is he e a clea posi i e ela ionship be ween engagemen wi h loo boxes and p ob-
lema ic gaming and/o gambling, o does his depend on he s udy cha ac e is ics? We hen
used his in o ma ion o o e sugges ions ega ding measu emen issues and p opose ideas o
meaning ul u u e esea ch.
Me hods
The esea ch and epo ing me hods o his scoping e iew a e consis en wi h he P e e ed
Repo ing I ems o Sys ema ic e iews and Me a-Analysis ex ension o Scoping Re iews
(PRISMA-ScR) [35], as ou lined in he S1 Table. In addi ion, he p esen s udy ollows he
Joanna B iggs Ins i u e’s “Guidance o conduc ing sys ema ic scoping e iews” [32,36], based
on ea lie wo k by A ksey and O’Malley [37] and Le ac e al. [38], o imp o e he u ili y and
obus ness o he esul s [32]. The objec i es, inclusion c i e ia, and me hods o analysis o
his e iew we e speci ied in ad ance and documen ed in a p o ocol adap ed om he p o ocol
empla e o he In e na ional p ospec i e egis e o sys ema ic e iews (PROSPERO) [39]
which is a ailable upon eques om he co esponding au ho .
Iden i ica ion o ele an s udies
A sys ema ic and comp ehensi e sea ch was ca ied ou om June 22, 2020 o July 22, 2020
(inclusi e o bo h da es) using he ollowing elec onic da abases: Google Schola , Web o Sci-
ence, and Scopus. The sea ch e ms used we e “loo boxes” and “loo box.” Because o he sca ci y
o ele an published li e a u e and he eme ging na u e o his opic, no limi s we e placed on
he publica ion da es o he a icles. Bibliog aphic e e ences om quali a i e o e iew s udies
we e e iewed o iden i y esea ch a icles no cap u ed by he elec onic sea ch. An addi ional
sea ch was subsequen ly ca ied ou in he las week o Ap il 2021 o de ec new publica ions.
Inclusion and exclusion c i e ia
The inclusion c i e ia a ose om he o mula ion o he e iew ques ions in he PCC (popula-
ion, concep , con ex ) o ma [32]. To be included in he scoping e iew, s udies had o mee
h ee eligibili y c i e ia: 1) p ima y empi ical s udies wi h samples o adul s and/o adolescen s
p o iding da a on he p e alence o engagemen wi h loo boxes in ideogames and/o da a on
he ela ionship be ween engagemen wi h loo boxes and p oblema ic gaming and/o p ob-
lema ic gambling; 2) published in English o Spanish; and 3) published in pee - e iewed jou -
nals. Quali a i e s udies, heses, epo s no published in academic jou nals, sys ema ic
e iews, and me a-analyses we e excluded. Howe e , hei e e ence lis s we e e iewed o
loca e po en ially eligible s udies. In cases o p e-p in s, au ho s we e con ac ed o check he
s a us o he s udies. One o hem p o ided he published s udy, which was included in he
inal selec ion [16].
Selec ion o he s udies
Fig 1 shows he selec ion p ocess o s udies o his e iew. In he ini ial sea ch, 292 manu-
sc ip s we e iden i ied om he h ee da abases consul ed. Se en manusc ip s iden i ied
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h ough o he sou ces (e.g., e e ence lis s and o iginal au ho s con ac ed by email) we e
added. All e e ences (n= 297) we e hen impo ed in o he Zo e o bibliog aphic manage .
Th ough he bibliog aphic manage he au ho s o de ed he e e ences and e iewed he i les,
abs ac s, and digi al objec iden i ie s o de ec duplica es. Duplica es we e elimina ed, and a
o al o 220 i ems we e ans e ed o he sc eening phase. To educe po en ial bias a his s age
o he e iew, wo independen esea che s (X.X. and Y.Y.) e alua ed all i les and abs ac s o
p e-selec a icles ha could po en ially mee he h ee eligibili y c i e ia. I an abs ac did no
allow assessmen o s udy eligibili y, he ull ex was scanned. A his s age, 188 i ems we e
Fig 1. PRISMA diag am o s udy selec ion p ocess. No e. C1: non-p ima y empi ical s udies; C2: s udies in a language o he han
English o Spanish; C3: no pee e iew.
h ps://doi.o g/10.1371/jou nal.pone.0263177.g001
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emo ed, lea ing a o al o 33 p e-selec ed i ems. Kappa’s coe icien o ag eemen be ween
he wo esea che s in he sc eening and p e-selec ion phase was 0.852. A e an in-dep h ead-
ing o he p e-selec ed a icles, 17 we e disca ded because hey did no mee all eligibili y c i e-
ia. The second esea che e iewed he inal selec ion, and po en ial disag eemen s abou a
s udy’s inal inclusion we e sol ed by a majo i y consensus among all eam esea che s. F om
he las sea ch conduc ed in Ap il 2021, wo a icles we e added. Finally, 16 s udies/a icles
we e included in he quali a i e syn hesis o his scoping e iew. No ably, wo o he s udies
[40,41] included wo di e en samples, as demons a ed in Table 1. This is speci ied in he
na a i e syn hesis o he esul s.
Da a ex ac ion
Table 1 p o ides a summa y o all in o ma ion ex ac ed om he 16 s udies included in he
inal e iew. A s anda dized ex ac ion shee (Mic oso Excel) con aining he ollowing a i-
ables was de eloped: au ho s and publica ion yea , coun y and yea o da a collec ion, sample
size and age and sex o pa icipan s, design and ec ui men , objec i es, measu emen ins u-
men s, and ou comes o he s udies ele an o he aims o his scoping e iew (i.e., a e o
engagemen wi h loo boxes and esul s conce ning he p esence o absence o a s a is ically
signi ican ela ionship be ween engagemen wi h loo boxes and p oblema ic gaming/gam-
bling). Table 2 shows he s udies’ loo box engagemen a es by age g oup (adolescen s e sus
adul s), ime ame, and beha io assessed (open/pu chase/sell). A e pilo ing he ex ac ion
shee wi hin he e iew eam, da a ex ac ion was pe o med by one eam esea che and
c oss-checked by ano he eam membe o accu acy.
Resul s
Cha ac e is ics o he s udies
O he 16 selec ed s udies (Table 1), nine we e ca ied ou wi h samples om a single place o
o igin. Fou o hese s udies used samples limi ed o Eu ope ( wo om he Uni ed Kingdom
[42,43], one om Denma k [2], and one om Ge many [16]. Th ee s udies we e conduc ed
using samples om he USA [6,40,41], and wo we e conduc ed using samples om Asia [44,
45]. Fo wo s udies, samples we e collec ed h ough he In e ne , and he o igin o he pa ici-
pan s was unknown [3,46]. The o he i e s udies ob ained samples om se e al coun ies [5,
11,12,47,48]. The s udy by Macey e al. [48] is no ewo hy o i s di e si y, as i included a
sample om 61 coun ies. All s udies we e ca ied ou be ween 2017 and 2019 wi h a c oss-
sec ional design and we e published in pee - e iewed jou nals be ween 2018 and 2021.
The sample sizes we e he e ogeneous, anging om 113 pa icipan s [40] o 13,042 [41].
The ages o s udy pa icipan s anged om 12 yea s [2] o 58 and olde [43]. O he 16 s udies
selec ed, only ou had samples made up exclusi ely o adolescen s be ween 12 and 18 yea s o
age [2,12,41,45], and en had samples made up o only adul s o e 18 yea s o age [3,5,6,11,
16,40,43,44,46,47]. The emaining wo s udies had mixed samples composed o bo h adoles-
cen s and adul s [42,48].
Fi e samples we e ob ained om he da a o ou la ge na ional s udies [2,16,41,45] con-
duc ed h ough popula ion-based sampling: one ep esen a i e sample o he adolescen popu-
la ion om Denma k [2], wo om Delawa e [41], one om Tokyo [45], and one
ep esen a i e sample o he Ge man popula ion o adul In e ne use s [16]. Addi ionally, one
s udy used pa icipan s ec ui ed om an online su ey by quo a sampling o ep esen he
UK adul popula ion [43]. Ano he s udy used an online panel su ey in which da a we e
weigh ed o e lec he age, sex, and egional p o ile o he popula ion be ween 16 and 24 yea s
old in G ea B i ain [42]. O hese se en samples, ou included game s, non-game s, gamble s,
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Table 1. Cha ac e is ics o he selec ed s udies (N = 16).
Au ho
(yea )
Me hods Ou comes
Yea and
coun y o
da a
collec ion
Pa icipan s (n, sex,
age)
Design and
ec ui men
Objec i es Measu ed a iables/
ins umen s
Loo
box de .
Loo
box p e alence
P oblema ic
gaming
P oblema ic
gambling
B ooks &
Cla k (2019)
2018,
No h
Ame ica
and
Canada
(n1) 144
pa icipan s �21 y/o
wi h p io ideo
game play and
amilia i y wi h loo
boxes; 48.6% ♀;
M = 34; SD = 10.
(n2) 113 s uden s
om The Uni e si y
o B i ish
Columbia �19 y/o
wi h p io ideo
game play and
amilia i y wi h loo
boxes; 12.1% ♀;
M = 21; SD = 2.4.
C oss-sec ional da a
om wo
con enience samples:
one collec ed ia
Amazon Mechanical
Tu k (n1) and he
o he om an online
su ey (n2).
Compensa ion o
$1.50 USD and a
cou se c edi we e
gi en o he n1 and
n2 pa icipan s,
espec i ely.
To es he
associa ions be ween
loo box engagemen
and gambling
beha io , u ilizing an
explo a o y
app oach.
Use, p e e ences,
i ual i em
alua ion,
p io i iza ion o
gaming o e o he
ac i i ies.
E e engaged wi h a
loo box (use,
pu chase), belie s
and beha io s, and
mon hly loo
box spending.
Risky Loo
Box Index (RLI)
In e ne Gaming
Diso de Scale
(IGDS)
P oblem Gambling
Se e i y Index
(PGSI)
Y Opening loo
box in a game:
88.9% (n1) and
94.8% (n2)
Buying loo
box o key ha
opens i : 49.3%
(n1) and 60.3%
(n2)
Selling loo box:
27.8% (n1) and
39.7% (n2).
Signi ican posi i e
associa ion
be ween RLI and
IGDS in he wo
samples.
Signi ican posi i e
associa ion be ween
sco es o RLI and
PGSI in he wo
samples.
DeCamp
(2021)
2018/2019,
Delawa e
(USA)
13042 public school
s uden s aged 13–16
y/o; 50% ♀, 50% ♂.
2018: (n1) 4678 (8 h
g ade); (n2) 3909
(11 h g ade).
2019: (n1) 2126 (8 h
g ade) (1531 we e
game s); (n2) 2329
(11 h g ade) (1340
we e game s).
C oss-sec ional da a
om he annual
Delawa e School
Su ey (DSS),
adminis e ed by he
Uni e si y o
Delawa e Cen e o
D ug and Heal h
S udies, wi h a
andomly selec ed
sample.
To examine one
dimension o
po en ial simila i ies
be ween loo boxes/
downloadable
con en and
gambling: isk and
p o ec i e ac o s.
T adi ional o ms o
gambling.
Digi al gaming
pu chases: numbe
o loo boxes
pu chased and imes
ha o he
downloadable
con en o in-game
i ems had been
pu chased in he pas
yea .
O he s (pa en al
bond, dep ession/
anxie y,
ic imiza ion,
bullying, subs ance
use, school g ades,
gende , and ace/
e hnici y).
N Buy loo
box (only 2019
samples)
(n1) 24.9%
(33.9% o
game s)
(n2) 17% (28.3%
o game s).
Does no p o ide
da a.
Does no p o ide
da a.
(Con inued)
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Table 1. (Con inued)
Au ho
(yea )
Me hods Ou comes
Yea and
coun y o
da a
collec ion
Pa icipan s (n, sex,
age)
Design and
ec ui men
Objec i es Measu ed a iables/
ins umen s
Loo
box de .
Loo
box p e alence
P oblema ic
gaming
P oblema ic
gambling
D ummond
e al. (2020)
2019, New
Zealand,
Aus alia,
and he
USA
1288 esponden s
(1049 ideo
game s �18 y/o).
63.4% ♀, 35.5% ♂;
M = 40; SD = 15.4.
(17% o he sample
me PGSI c i e ia o
gambling p oblems).
C oss-sec ional da a
om h ee la ge
c oss-sec ional,
c oss-na ional
samples ec ui ed
h ough Qual ics’
Su ey Ta ge ing
Tool. Exclusion o
pa icipan s who
endo sed he
s a emen “I once
owned a h ee
headed dog”; who
indica ed ha hey
ne e played ideo
games; and who we e
g ea e han 3.29
s anda d de ia ions
om he mean on
loo box spending
(equa ing o $104.20
USD).
To examine whe he
p oblem gambling
and p oblem gaming
symp omology made
independen
con ibu ions o
p edic ing loo
box spending.
Risky Loo
Box Index (RLI)
In e ne Gaming
Diso de Scale
(IGDS)
P oblem Gambling
Se e i y Index
(PGSI)
Pas mon h
spending on loo
boxes.
O he s (posi i e and
nega i e a ec ,
psychological
dis ess).
N Does no
p o ide da a.
Signi ican posi i e
associa ion
be ween IGD
symp omology,
loo box spending,
and RLI.
Signi ican posi i e
associa ions be ween
mon hly loo
box spending, PGSI,
and RLI.
E en e al.
(2021)
2019,
Tu key
752 ideo game s
(eSpo s playe s and
uni e si y s uden s)
�18 y/o.
31% ♀, 69% ♂.
C oss-sec ional da a
om an online
su ey add essed o
membe s o a
da abase om ESL
Tu key Ama eu
eSpo s playe s and
Talewo lds
En e ainmen , use s
o Tu kish gaming
o ums and
uni e si y s uden s
( ewa ded wi h
bonus c edi ).
To e alua e he
ela ionships o loo
box engagemen
wi h gende ,
diso de ed gaming,
using massi e
mul iplaye online
ole-playing games,
and mo i es o
online gaming
among young adul s.
Weekly gaming ime.
Mo i es o online
gaming.
In e ne Gaming
Diso de Scale–Sho
Fo m (IGDS9-SF)
Las yea loo
box pu chases.
N Pu chase loo
boxes: 22.7%.
Signi ican posi i e
associa ion
be ween loo
box pu chase and
he se e i y o IGD
symp oms.
Does no p o ide
da a.
Ide e al.
(2021)
2017,
Japan
1615 adolescen
game s aged 14 yea s
(bo n be ween
Sep embe 2002 and
Augus 2004).
37% ♀, 63% ♂.
(16.2% o game s
exhibi ed ou o
mo e addic i e
symp oms in online
gaming).
C oss-sec ional da a
om he Tokyo Teen
Coho (TTC) s udy,
an ongoing,
p ospec i e, and
popula ion-based
bi h coho s udy on
2667 adolescen s and
hei p ima y
ca egi e s ec ui ed
om h ee
municipali ies using
he esiden egis e s.
To in es iga e he
associa ion be ween
loo box pu chasing
among adolescen s
and pa en s, and
p oblem online
gaming in
popula ion-based
samples.
Loo box pu chase
(no ime ame
speci ied).
Gaming Diso de
(DSM-5 In e ne
gaming diso de
c i e ia)
N Pu chase loo
boxes: 3.5%.
Signi ican posi i e
associa ion
be ween loo
box pu chase and
p oblem online
gaming.
Does no p o ide
da a.
(Con inued)
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Table 1. (Con inued)
Au ho
(yea )
Me hods Ou comes
Yea and
coun y o
da a
collec ion
Pa icipan s (n, sex,
age)
Design and
ec ui men
Objec i es Measu ed a iables/
ins umen s
Loo
box de .
Loo
box p e alence
P oblema ic
gaming
P oblema ic
gambling
King e al.
(2020)
2018, USA,
Aus alia,
Canada,
and UK
428 Fo ni e
game s �18 y/o.
6.5% ♀, 91.8% ♂.
57% 18–21 y/o, 85%
up o 30 y/o
(M = 23.5 y/o,
SD = 7.3,
median = 21).
(14% o he sample
me DSM-5 c i e ia
o In e ne Gaming
Diso de ).
C oss-sec ional da a
om online o ums
ela ed o Fo ni e
(e.g., Epic Games,
Reddi o ums).
To in es iga e
gaming mo i a ions
and beha io s, as
well as online social
ne wo k in luences,
in ela ion o
mic o ansac ion
spending and
gaming diso de
(GD) symp oms.
Fo ni e social play
and in luence,
Fo ni e gaming and
expendi u e:
Expendi u e on loo
boxes (daily, weekly,
mon hly and
yea ly).
Gaming Diso de
(DSM-5 In e ne
gaming diso de
c i e ia)
Pe cep ions o
Fo ni e alue (PFV)
O he s
(impulsi eness,
gaming-con ingen
sel -wo h).
N Does no
p o ide da a.
No signi ican
associa ion
be ween loo
box expendi u e
(yes/no and
amoun ) and GD
symp oms.
Does no p o ide
da a.
K is iansen
& Se e in
(2020)
2018,
Denma k
1137 adolescen s
aged 12–17 y/o (995
played ideo games
in he p io 12
mon hs).
50.6% ♀, 49.5% ♂.
43.7% 12–13 y/o;
41% 14–15 y/o;
15.4% 16 y/o.
C oss-sec ional da a
om a su ey among
a ep esen a i e g oss
sample o 5000
Danish adolescen s
(12–16 y/o) d awn
andomly om he
Danish Ci il
Regis a ion Sys em.
Web su ey sen ,
mainly digi ally, o a
selec ed pa en o he
pa icipan .
To examine loo
box engagemen
pa e ns and links
wi h p oblem
gambling se e i y.
Mone a y gambling
in ol emen ,
simula ed gambling
in ol emen , sel -
e alua ed exposu e
om gambling
ad e isemen s, and
a subsec ion on
gambling ela ed
gaming including
loo boxes (pas 12
mon hs ob ainmen ,
pu chase, and sale).
Sou h Oaks
Gambling Sc een-
Re ised o
Adolescen s
(SOGS-RA).
N To al
engagemen
among game s
56.1% (40%
ea ned; 20%
pu chased;
10.6% sold).
Ob ained loo
box: 44.3% 12–
13 y/o; 40.7%
14–15 y/o;
42.4% 16–17 y/
o.
Buy loo box:
20.5% 12–13 y/
o; 17.8% 14–15
y/o; 23.5% 16–
17 y/o.
Does no p o ide
da a.
Signi ican posi i e
associa ion be ween
loo box pu chasing
o selling and PG
se e i y (no only
ob ained), e en
con olling o
demog aphic ac o s.
(Con inued)
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and 66.1% (in a sample o game s who also gambled [3]). Fu he mo e, in a sample comp ised
o game s, one s udy de e mined ha he mon hly p e alence o loo box pu chases was 62.4%
[46]. Two s udies examined his p e alence h oughou pa icipan s’ li e imes, e ealing a es
o 49.3% [40] and 78% [11]. One s udy included wo di e en con enience samples o adul
game s [40]. I add essed he li e ime p e alence o di e en loo -box- ela ed beha io s, such
as 1) pa icipa ing in games con aining a loo box, 2) opening a loo box, 3) buying a loo box,
and 4) selling a loo box. The p e alence a e o opening a loo box was 88.9% in he i s sam-
ple (n= 144) and 94.8% in he second sample (n= 113). In he case o loo box pu chases, he
a es we e 49.3% in he i s sample and 60.3% in he second sample. In he case o selling loo
boxes, he a es we e 27.8% in he i s sample and 39.7% in he second sample. The es o he
s udies in ol ing adul s (n= 3) did no p o ide da a on he p e alence o engagemen wi h
loo boxes; hey only measu ed loo box expendi u e [5,6,47].
In mixed samples o adul s and adolescen s. Two s udies examined mixed samples o adul s
and adolescen s [42,48]. One used a con enience sample and de e mined ha 46.2% o gam-
e s who also gambled o wa ched eSpo s (n= 582) had bough a loo box in he p io yea
[48]. The o he s udy demons a ed an annual loo box pu chase p e alence o 12.1% using an
online panel su ey o 3,549 B i ish pa icipan s be ween 16 and 24 yea s, wi h younge people
being he bigges pu chase s (38.9% we e be ween 16 and 18 yea s o age) [42].
Associa ion be ween engagemen wi h loo boxes and p oblema ic gaming and gam-
bling. Eigh o he 16 s udies analyzed he ela ionship be ween engagemen wi h loo boxes
and p oblema ic gaming. Se en analyzed adul samples [3,5,16,40,43,44,47]. One sample
was ep esen a i e o he Ge man adul popula ion o In e ne use s [16], and ano he used
quo a sampling o ep esen he UK adul popula ion in e ms o sex, age, and e hnici y [43].
One o he eigh s udies used a sample o adolescen game s om a popula ion-based bi h
coho s udy in Japan [45]. Six o he eigh s udies e ealed a posi i e, s a is ically signi ican
ela ionship be ween he wo cons uc s [3,5,40,43–45]. Howe e , one s udy did no ind his
ela ionship [47], and ano he showed mixed esul s [16]. O hose six s udies, i e epo ed a
posi i e ela ionship be ween loo box pu chases and p oblema ic gaming as measu ed by he
In e ne Gaming Diso de Scale (IGDS [43,49]), he In e ne Gaming Diso de Scale–Sho
Fo m (IGDS9-SF; [44,50]), and he DSM-5 In e ne Gaming Diso de c i e ia (IGD; [3,23,
43,45]). Two s udies epo ed a posi i e ela ionship be ween RLI sco e and highe sco es o
p oblema ic gaming as measu ed by he IGDS [5,40]. A s udy by on Meduna e al. [16] indi-
ca ed ha 68.9% o loo boxes pu chase s we e p oblem game s acco ding o an adap ed P ob-
lem Gambling Se e i y Index (PGSI) sco e o Pay2Win gaming, bu his s udy highligh ed
mixed esul s in he eg ession models; namely, he au ho s obse ed ha ha ing p oblems
wi h Pay2Win gaming was signi ican ly associa ed wi h loo box pu chasing (yes/no) in all
h ee es ed models bu had no signi ican e ec on he equency o loo box pu chasing.
D ummond e al. [5] obse ed a posi i e co ela ion be ween loo box spending and highe
sco es o diso de ed gaming as measu ed by he IGDS. Only one s udy, ca ied ou in a sam-
ple o adul Fo ni e game s, did no ind a posi i e ela ionship be ween loo box expendi u e
(yes/no and amoun ) and IGD symp oma ology as measu ed by he DSM-5 c i e ia [47]. No a-
bly, some s udies ound he associa ion be ween loo box engagemen and p oblem gaming o
be associa ed wi h pe sonal a iables, such as he pa icipan s’ sex. Fo example, Ide e al. [45]
obse ed in a sample o Japanese adolescen s aged 14 ha he likelihood o p esen ing p oblem
online gaming was signi ican ly highe in adolescen emale game s who pu chased loo boxes
(OR 6.73, 95% CI 2.42–18.72) han in male game s who pu chased loo boxes (OR 2.88, 95%
CI 1.51–5.51).
Fu he mo e, 12 o he 16 selec ed s udies analyzed he ela ionship be ween engagemen
wi h loo boxes and p oblema ic gambling. They all indica ed a posi i e associa ion be ween
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he wo cons uc s [2,3,5,6,11,12,16,40,42,43,46,48]. Two o hese 12 s udies we e ca ied
ou using adolescen samples [2,12], wo wi h mixed samples o adolescen s and adul s [42,
48], and he emaining eigh wi h adul samples. Only ou o hese 12 s udies used ep esen a-
i e samples o hei popula ions o in e es : one used a ep esen a i e sample o he Ge man
adul popula ion o In e ne use s [16]; one used quo a sampling o ep esen he UK adul
popula ion in e ms o sex, age, and e hnici y [43]; one used a ep esen a i e sample o 1137
Danish adolescen s be ween 12 and 17 yea s o age [2]; and one used an online panel su ey o
3,549 B i ish you h be ween he ages o 16 and 24 [42]. Se en o hese 12 s udies epo ed a
posi i e ela ionship be ween he pu chase o loo boxes and p oblema ic gambling as mea-
su ed by he PGSI [51] in adul s [3,16,42,43,46,48] and he Sou h Oaks Gambling Sc een–
Re ised o Adolescen s (SOGS-RA; [2,52]) in adolescen s. Two s udies ound a posi i e ela-
ionship be ween RLI sco e and highe sco es o p oblema ic gambling as measu ed by he
PGSI [5,40]. Fi e s udies ound a posi i e co ela ion be ween loo box expendi u e and highe
sco es o p oblem gambling as measu ed by he PGSI in adul s [5,6,11,46] and he Canadian
Adolescen Gambling In en o y (CAGI; [53]) in adolescen s [12]. The s udy by on Meduna
e al. [16] indica ed ha 45.9% o loo box pu chase s we e p oblem gamble s acco ding o he
PGSI, bu his s udy highligh ed mixed esul s in he eg ession models. Namely, he au ho s
obse ed ha being a p oblem gamble yields a signi ican posi i e e ec on loo
box pu chasing (yes/no) and loo box pu chasing equency in some o he eg ession models
bu no in o he s.
Some s udies ound ha he associa ion be ween engagemen wi h loo boxes and p oblem
gambling was associa ed wi h a iables such as sex, age, and ype and le el o loo
box engagemen . Fo example, K is iansen & Se e in [2] ound, in a ep esen a i e sample o
Danish adolescen s, ha his ela ionship was ma kedly s onge o emales han o males
( emales: local γ= 0.777, p = 0.043; males: local γ= 0.541, p <0.01) and o he wo olde
g oups (12–13 y s.: local γ= 0.294, p = 0.322; 14–15 y s.: local γ= 0.779, p <0.01; 16–17 y s.:
local γ= 0.565, p <0.1). They also ound ha his link was dependen upon he le el o engage-
men . They ound ha he p opo ions o a - isk and p oblem gamble s we e highe among
hose who had pu chased o sold i ems om a loo box han among hose who had ob ained a
ee loo box. Simila ly, Zendle e al. [46] obse ed ha he posi i e associa ion be ween
engagemen wi h loo boxes and PGSI sco es in a con enience sample o adul game s was
highe when pa icipan s paid o he loo boxes han when hey did no .
Discussion
To da e, nume ous s udies abou loo boxes ha e been published. Howe e , o ou knowledge,
no wo k has summa ized he p e alence a es o di e en o ms o engagemen among adoles-
cen s and adul s o syn hesized he mos ecen empi ical esul s abou he ela ionships
be ween hese o ms o engagemen wi h loo boxes and p oblema ic gaming and p oblema ic
gambling, aking in o accoun me hodological aspec s o he exis ing s udies. The p esen
scoping e iew aimed o concu en ly examine hese aspec s o he exis ing li e a u e.
Wi h ega d o me hods o measu ing engagemen wi h loo boxes in he exis ing p ima y
empi ical s udies, we obse ed s ong ag eemen conce ning he cha ac e is ics o loo boxes,
such as he i uali y o he objec s, andomness, and mone a y paymen (wi h eal cu ency
o in-game cu ency ea ned h ough gaming ime). Ne e heless, e y ew s udies we e su i-
cien ly consis en in hei me hods o allow compa ison o hei esul s. Each s udy measu ed
di e en aspec s o loo boxes, such as he opening, pu chase (yes/no), equency, numbe o
loo boxes and/o loo box expendi u e, and use ac oss a ious ime ames, making i di icul
and inapp op ia e o compa e esul s be ween s udies. Addi ionally, as a as we know, he e is
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only one alida ed ins umen ha e alua es isky beha io s su ounding he use o loo boxes
— he Risky Loo Box Index [40]. Howe e , i would be ad isable o ca y ou mo e obus
analyses o his ool’s psychome ic p ope ies.
The he e ogenei y o he me hods used p e en us om uly unde s anding he magni ude
o he phenomenon. Taking all da a ex ac ed om he s udies wi hou di e en ia ing among
ime ames o loo box beha io s (pu chase, opening, e c.), p e alence a es among adoles-
cen s a ied be ween 3.5% [45] and 44.3% [2], and hose among adul s a ied be ween 7.8%
[43] and 94.8% [40]; howe e , hese da a a e incompa able among hem. The annual pu chase
p e alence among adolescen game s a ied be ween 20% [2] and 33.9% [41]. Among adul
game s o e he age o 18, he annual pu chase p e alence a ied be ween 22.7% [44] and
44.2% [48], bu he ange was g ea e among game s who also gambled (46.2%–66%) [3,48].
As we can see, among game s, annual loo box pu chase p e alence was highe in adul s han
in adolescen s. This makes sense conside ing ha mino s a e subjec ed o pa en al con ol,
enjoy less eedom, and ha e less pu chasing powe . Howe e , in s udies ha used gene al
popula ion samples, he a e age annual pu chase p e alence among adolescen s aged 13–14
yea s was highe han ha among pa icipan s aged 16–24 yea s and ha among adul s (24.9%,
12.1%, and 7.8%, espec i ely) [41–43]. This sugges s ha loo box usage is p e alen among
adolescen s, ega dless o whe he hey ecognized hemsel es as game s o no . In addi ion,
hese esul s a e in line wi h hose o o he wo ks sugges ing ha age is nega i ely co ela ed
wi h his beha io [11,16,48,54], as younge people, in gene al, a e mo e ech sa y and open
o ying some hing new. Howe e , once an indi idual comes in o con ac wi h a loo box, age
is no a mode a ing a iable ha educes he equency o loo box usage [16]. In any case, i is
expec ed ha engagemen wi h loo boxes among adolescen s will con inue g owing in he
absence o ele an in e en ions o legal measu es.
Addi ionally, he di e ences in esul s ac oss he exis ing s udies may be associa ed wi h
cul u al and legal a iables speci ic o each coun y. Fo example, he 3.5% loo box pu chase
a e in Tokyo [45] and he 7.8% a e in he UK [43] a e a om he 38.9% a e in Ge many
[16]. This could be a esul o di e ences in he legal s a us o loo boxes in hese coun ies. In
Ge many, he e a e legal ba ie s o egula ing loo boxes as gambling [19], whils in he UK,
loo boxes a e co e ed by he gambling legisla ion, and in Japan, some ypes o loo boxes a e
p ohibi ed [31].
Conce ning he las o ou esea ch ques ions, he e appea s o be a posi i e ela ionship
be ween loo boxes and p oblema ic gaming and gambling. Howe e , u he esea ch is
needed, and sampling bias mus be conside ed when in e p e ing he esul s o he exis ing
s udies. I is wo h men ioning ha only eigh o he s udies analyzed he ela ionship be ween
loo boxes and p oblema ic gaming, and only one o hem used an adolescen sample, despi e
he ac s ha 1) access o loo boxes occu s exclusi ely h ough ideogames and 2) adolescen s
a e hea y ideogame use s [55]. In gene al, a posi i e associa ion be ween he cons uc s was
obse ed [3,5,16,40,43–45,47]. Howe e , his was p ima ily ue o adul samples and, in
some cases, o an o e ep esen a ion o pa icipan s classi ied as p oblem game s [3,5,45,
47]. The only s udy ha did no ind an associa ion be ween loo boxes and gaming diso de
symp oms was based exclusi ely on Fo ni e [47], which may ha e in luenced i s esul s.
In addi ion, he di e en ia ed e ec o opening ee loo boxes ( e sus paid loo boxes)
should be conside ed. The inc ease in gaming ime equi ed o ob ain loo boxes migh sugges
a possible link wi h he de elopmen o p oblema ic gaming, bu none o he s udies e iewed
add essed his. Howe e , some s udies in ou scoping e iew examined a simila line o
esea ch, poin ing ou ha paid loo boxes a e mo e s ongly associa ed wi h p oblem gam-
bling han unpaid loo boxes. Fo example, K is iansen and Se e in [2] s essed ha he e was
only a ela ionship be ween loo boxes and p oblem gambling when i came o buying o
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selling loo boxes, no when hey we e ob ained o ee. Fu he mo e, Zendle e al. [48]
obse ed a s onge associa ion be ween loo boxes and p oblem gambling when a p ice was
paid han when hey we e ob ained o ee.
As a as he ela ionship wi h gambling is conce ned, i seems easonable o in e ha he
gambling nuance a ached o loo boxes a o s he ela ionship be ween loo box pu chases
and p oblema ic gambling [3,16]. This has been co obo a ed by he exis ing s udies o da e in
bo h adul and adolescen samples and in a ecen seconda y analysis o loo box expendi u e
da a [34]. Howe e , cau ion is necessa y when in e p e ing such esul s. The scien i ic li e a-
u e is s ill sca ce, and an o e ep esen a ion o adul s and people wi h gambling p oblems [3,
5,46,48] was obse ed in he samples o some s udies included in his scoping e iew. This is
also ue o he a o emen ioned seconda y analysis by Close e al. [34]. Such a limi a ion may
in luence he esul s and limi s gene aliza ion. On he o he hand, al hough ew s udies ha e
simul aneously analyzed he ela ionship be ween loo boxes, p oblema ic gaming, and p ob-
lema ic gambling [e.g., 3,5,14,38,41], hei esul s poin o a s a is ically signi ican ela ion-
ship be ween pu chase o (o expendi u e owa d) loo boxes and he wo p oblems, in line
wi h he esul s o a me a-analysis by Ga ea e al. [14]. In sho , i can be concluded ha loo
boxes a e linked wi h p oblems ela ed o bo h o gaming and gambling; howe e , o lea n
mo e abou hese ela ionships, longi udinal s udies and ep esen a i e samples a e necessa y.
All s udies in he p esen e iew we e c oss-sec ional in na u e, and mos o hem we e o lim-
i ed ep esen a i eness. The e o e, hey do no allow es ablishmen o causal e ec s be ween
a iables o ex apola ion o hei esul s o he gene al popula ion.
Recommenda ions o esea ch
In iew o he esul s ob ained in his scoping e iew, some ecommenda ions can be made o
u he esea ch. Fi s , u u e s udies should s anda dize measu emen s o engagemen wi h
loo boxes o allow o compa isons be ween s udies. This will also a o o e all comp ehen-
sion o he cons uc and acili a e unde s anding o he eal magni ude o his phenomenon.
Fo example, p o iding s udy pa icipan s wi h an es ablished de ini ion o loo boxes (pe haps
wi h some examples and pic u es) be o e asking ques ions abou usage habi s migh be a good
p ac ice. A po en ial s a ing poin o a de ini ion ha includes all necessa y elemen s o a loo
box as p oposed by di e en au ho s [16–20] migh be he ollowing: “a loo box is a i ual
objec (such as a ches , a key, en elope, e c.) wi hin a ideogame ha o e s andom con en s
(such as equipmen , weapons, cha ac e s, e c.) wi hin he game i sel in exchange o an
amoun o money (ei he eal money paid di ec ly o eal money ha has been ans o med
in o a i ual cu ency wi hin he ideogame o game ecosys em).”
Secondly, ega ding he ime ame, we ecommend including se e al ac o s ha can be
aluable. Cu en ly, mos exis ing li e a u e has e alua ed loo box engagemen du ing he
p io yea and whils con inue doing so, would acili a e compa ison wi h he cu en li e a-
u e, i migh also be o in e es o know whe he his beha io has aken place in he las yea
(yes/no), equency which wi h i happens, ( a ely, once o wice, o en, o many imes in he
las yea ) and he a e age numbe o loo boxes pu chased/opened/sold o a e age expendi-
u e. Howe e , when using con inuous measu es, i will be desi able o ask abou sho e pe i-
ods (e.g., he p e ious mon h), since pa icipan s’ esponses ega ding he annual o li e ime
ime ame may con ain mo e biases [56].
Thi dly, i will also be ele an o ca y ou in es iga ions in which he e is a clea dis inc-
ion be ween he opening o ee loo boxes and he opening o paid loo boxes. This will allow
analysis o hei di e ing e ec s on p oblema ic gaming and/o gambling. I may also be ele-
an o pe o m analysis as a unc ion o he ideogames in which loo boxes a e used o o he
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ype o loo box (e.g., pu ely cosme ic o cen al o he game). In addi ion, i should be asked
whe he hese pu chases a e made di ec ly wi h eal money o wi h i ual cu ency h ough a
game/pla o m ecosys em (a e paymen wi h eal money).
Fu he mo e, acili a o s o u u e popula ion-based s udies should include simila p opo -
ions o males and emales as well as wide age anges, p o ide agg ega ed and disagg ega ed
da a o each subsample, discuss hei esul s wi h simila subsamples om o he s udies, and
ake s eps o a oid limi a ions o in e p e a ion and gene aliza ion. Addi ionally, in iew o he
exis ing da a [57–59], i may be no ewo hy o inc ease he p opo ions o gi ls in s udies
abou loo box engagemen . I would also be ad isable o di e en ia e be ween analyses wi h
clinical and non-clinical samples and o use clinical and speci ic ins umen s o he online
con ex , such as he Online Gambling Diso de Ques ionnai e [60]. Al e na i ely, when using
he PGSI, i migh be ad isable o explici ly s a e ha he s udy is no assessing a clinical p ob-
lem bu a he i s mo e social aspec s [61]. Finally, addi ional ins umen al s udies a e needed
o assess he cons uc o p oblema ic loo box usage as i ela es o gaming and gambling p ob-
lems, bo h in gene al and clinical popula ions.
The p esen scoping e iew does ha e some limi a ions ha should be men ioned. Fi s , he
e iew included a small numbe o s udies, which may be due o he no el y o he subjec ma -
e and he inclusion c i e ia chosen. Fo example, ele an s udies no published in pee -
e iewed jou nals (e.g., heses, unpublished disse a ions, epo s) we e le ou o his e iew.
Secondly, he he e ogenei y and limi ed ep esen a i eness o some o he samples hinde ed
he p ocess o compa ison be ween s udies, which may lead o biases in hei in e p e a ion,
and hei esul s canno be ex apola ed o he gene al popula ion. Fo his eason, we p e-
sen ed he age o he s udy sample, he ime ame, and he beha io assessed in each s udy as
sepa a e ac o s. Thi dly, all s udies included in his e iew we e c oss-sec ional, which mus
be conside ed when in e p e ing esul s on he ela ionship be ween loo boxes and p oblem-
a ic gaming and/o gambling. Finally, cau ion is ad ised because he scien i ic li e a u e is s ill
sca ce and e y ew s udies di e en ia ed be ween ypes o engagemen (opening, pu chasing,
o selling) in hei analyses.
Conclusion
In summa y, his s udy con ibu es o a be e unde s anding o engagemen wi h loo boxes
in ideogames. Fi s , his s udy con i ms ha he use o loo boxes is p e alen among bo h
adul s and adolescen s. The esul s also sugges ha he pu chase o loo boxes is a equen
p ac ice among mino s. Howe e , da a on his p e alence a e he e ogeneous, p ima ily due o
me hodological di e ences (e.g., he ope a ionaliza ion o engagemen wi h loo boxes, he
samples’ cha ac e is ics, and a ious cul u al o legal con ex s). This makes he esul s incom-
pa able ac oss s udies and coun ies. Second, a ailable da a sugges a signi ican ela ionship
be ween engagemen wi h loo boxes and gambling and gaming p oblems. Finally, i is neces-
sa y o u u e s udies o be conduc ed in a manne ha allows compa abili y— o example,
using common de ini ions, simila ime ames, and simila assessmen ins umen s (pa icu-
la ly o assess he ela ionship wi h p oblema ic gaming and gambling). E ec i e policies o
p e en ing p oblema ic gaming and/o gambling mus be based on scien i ic e idence; hus, a
alid and ho ough unde s anding o he magni ude o his phenomenon is essen ial.
Suppo ing in o ma ion
S1 Table. PRISMA-ScR checklis .
(DOCX)
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Au ho Con ibu ions
Concep ualiza ion: I ene Mon iel, A a
´nzazu Bas e a-Gonza
´lez, Juan M. Machimba ena,
Je
´ssica O ega-Ba o
´n, Joaquı
´n Gonza
´lez-Cab e a.
Da a cu a ion: I ene Mon iel, A a
´nzazu Bas e a-Gonza
´lez.
Funding acquisi ion: Joaquı
´n Gonza
´lez-Cab e a.
Me hodology: I ene Mon iel, A a
´nzazu Bas e a-Gonza
´lez, Juan M. Machimba ena, Joaquı
´n
Gonza
´lez-Cab e a.
Supe ision: Joaquı
´n Gonza
´lez-Cab e a.
W i ing – o iginal d a : I ene Mon iel, A a
´nzazu Bas e a-Gonza
´lez.
W i ing – e iew & edi ing: I ene Mon iel, A a
´nzazu Bas e a-Gonza
´lez, Juan M. Machim-
ba ena, Je
´ssica O ega-Ba o
´n, Joaquı
´n Gonza
´lez-Cab e a.
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PLOS ONE
A scoping e iew on loo box engagemen and associa ion wi h p oblema ic gaming/gambling
PLOS ONE | h ps://doi.o g/10.1371/jou nal.pone.0263177 Janua y 27, 2022 23 / 23
