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Ex e nal Valida ion o he CHOKAI Sco e o he P edic ion o U e e al S ones
Khali a AlQu aini¹, Suad Albulushi²* and Abdulmunim Al a si³
¹Eme gency Depa men , Suha Hospi al, Musca , Oman
²Eme gency Depa men , Al-Nahda Hospi al, Musca , Oman
³Eme gency Depa men , Royal Hospi al, Musca , Oman
Ci a ion: AlQu aini K, Albulushi S, Al a si A. Ex e nal Valida ion o he CHOKAI Sco e o he P edic ion o
U e e al S ones. In Clinc Med Case Rep Jou . 2025;4(11):1-8.
Recei ed Da e: 31 Oc obe , 2025; Accep ed Da e: 04 No embe , 2025; Published Da e: 06 No embe , 2025
*Co esponding au ho : Suad Albulushi. Eme gency Depa men , Al-Nahda Hospi al, Musca , Oman
Copy igh : ©2025 Albulushi S, e al. his 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.
__________________________________________________________________________________________
ABSTRACT
Backg ound: Accu a e isk s a i ica ion o pa ien s p esen ing wi h loin pain is essen ial o op imize
diagnos ic imaging and educe unnecessa y adia ion exposu e. The CHOKAI sco e is a ecen ly de eloped
clinical p edic ion ool designed o es ima e he p obabili y o u e e al s ones wi hou immedia e compu ed
omog aphy (CT) scanning. This s udy aimed o ex e nally alida e he CHOKAI sco e in an Omani popula ion
and compa e i s diagnos ic pe o mance wi h es ablished sco ing sys ems.
Me hods: We conduc ed a mul icen e p ospec i e obse a ional s udy om No embe 2020 o Sep embe
2021 ac oss h ee e ia y hospi als in Oman. Adul pa ien s p esen ing o he eme gency depa men wi h acu e
lank, loin o lowe abdominal pain we e en olled. Clinical da a, u ine analysis and poin -o -ca e
ul asonog aphy (POCUS) we e collec ed o calcula e he CHOKAI and STONE sco es. All pa ien s
subsequen ly unde wen CT o al e na i e imaging o con i ma ion. Recei e ope a ing cha ac e is ic (ROC)
analysis was pe o med o assess diagnos ic accu acy, wi h he a ea unde he cu e (AUC), sensi i i y,
speci ici y and op imal cu -o poin s calcula ed.
Resul s: A o al o 200 pa ien s we e included (mean age 39.4 ± 16.1 yea s), o whom 128 (64.3%) we e
diagnosed wi h u e e al s ones. The CHOKAI sco e demons a ed an AUC o 0.831 (95% CI: 0.771–0.880). A
he op imal cu -o o >5, sensi i i y was 82.0% and speci ici y was 67.6%. Hyd oneph osis was de ec ed in
73.4% o pa ien s on POCUS. While sensi i i y was accep able, speci ici y ell sho o he desi ed ≥80%
h eshold.
Conclusion: The CHOKAI sco e showed mode a e diagnos ic pe o mance in p edic ing u e e al s ones in he
s udied popula ion. Al hough i may assis in iden i ying high- isk pa ien s, i should no eplace con i ma o y
CT scanning. In eg a ing he CHOKAI sco e wi h clinician expe ise and imp o ed ul asound aining may
enhance diagnos ic accu acy and suppo mo e judicious use o imaging.
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Keywo ds: Loin pain; CHOKAI sco e; Eme gency depa men
INTRODUCTION
Acu e enal colic, mos o en caused by u e e oli hiasis, is a common p esen a ion in he eme gency depa men
(ED) and is ypically cha ac e ized by lank, loin o lowe abdominal pain symp oms ha a e o en non-speci ic
[1,2]. Non-con as helical compu ed omog aphy (NCCT) has become he gold s anda d diagnos ic modali y o
u e e al s ones due o i s high sensi i i y and speci ici y [1,2]. Howe e , epea ed CT imaging aises signi ican
conce ns ega ding cumula i e adia ion exposu e, pa icula ly since u e e oli hiasis is a ecu en condi ion,
wi h elapse a es epo ed in 15% o pa ien s wi hin one yea and 30–50% wi hin en yea s [3-7].
To minimize unnecessa y adia ion exposu e, clinical p edic ion ools ha e been de eloped o guide imaging
decisions in suspec ed cases o u e e oli hiasis. One such model is he STONE sco e, p oposed by Moo e e al
[8]. The sco e inco po a es i e clinical a iables -sex, du a ion o pain, nausea/ omi ing, haema u ia and ace -
o es ima e he p obabili y o u e e al s ones, ca ego izing pa ien s in o low, in e media e o high- isk g oups.
While he STONE sco e demons a ed u ili y as a sc eening ool, i has se e al limi a ions. No ably, he
inclusion o “ ace” (black s non-black) as a p edic o has been ques ioned o i s limi ed gene alizabili y ac oss
di e en popula ions. In addi ion, he sco e omi s assessmen o hyd oneph osis, a key ul asonog aphic inding
commonly used in he ini ial e alua ion o suspec ed enal colic.
To add ess hese limi a ions, Fukuha a e al. de eloped he CHOKAI sco e, which adds age, p io his o y o
kidney s ones and hyd oneph osis de ec ed on ul asonog aphy o he o iginal STONE sco e componen s. The
CHOKAI sco e anges om 0 o 11 poin s and demons a ed imp o ed diagnos ic pe o mance compa ed wi h
he STONE sco e in i s ini ial alida ion s udy. Howe e , he s udy’s single-cen e design and signi ican
selec ion bias, whe e app oxima ely 80% o eligible pa ien s we e excluded, limi he ex e nal gene alizabili y o
i s indings.
Gi en he a iabili y in demog aphic and clinical p o iles ac oss popula ions, ex e nal alida ion o he
CHOKAI sco e in di e se se ings is essen ial be o e i s b oade clinical implemen a ion. In Oman, o ins ance,
he “ ace” componen o he STONE sco e is no applicable, u he emphasizing he po en ial u ili y o a
modi ied and ex e nally alida ed p edic ion ool. The e o e, his s udy aimed o ex e nally alida e he
CHOKAI sco e in pa ien s p esen ing o Omani EDs wi h suspec ed u e e al s ones, assess i s diagnos ic
accu acy compa ed o NCCT indings and explo e i s po en ial ole in op imizing imaging s a egies.
MATERIALS AND METHODS
S udy design and Se ing
This mul icen e p ospec i e obse a ional s udy was conduc ed om No embe 2020 o Sep embe 2021 ac oss
h ee e ia y hospi als in Oman: Royal Hospi al, Soha Hospi al and Al-Nahda Hospi al. The s udy included
adul pa ien s p esen ing o he eme gency depa men (ED) wi h acu e lank, loin o lowe abdominal pain
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suspec ed o be due o u e e oli hiasis. The s udy p o ocol was app o ed by Resea ch and E hical Re iew &
App o al Commi ee Minis y o Heal h, Sul ana e o Oman.MoH/DGPS/CSR/PROPOSAL
APPROVED/53/2020. W i en in o med consen was ob ained om all pa icipan s o hei gua dians be o e
en olmen .
Pa icipan s
Inclusion c i e ia we e:
Age ≥18 yea s.
P esen a ion o he ED wi h acu e lank, loin o lowe abdominal pain.
Exclusion c i e ia we e:
Declining o pa icipa e in he s udy.
Abno mal i al signs a p esen a ion (body empe a u e >38°C o sys olic blood p essu e <90 mmHg).
Lack o app o al o consen .
Da a Collec ion
Be o e he s udy began, all pa icipa ing physicians and nu ses ecei ed s anda dized aining on s udy
p ocedu es, da a collec ion o ms and ul asound echniques. Eligible pa ien s we e iden i ied by he ea ing
physicians o nu ses based on p esen ing symp oms and ini ial assessmen s. A s uc u ed ques ionnai e was
adminis e ed o collec du a ion o pain, p esence o nausea o omi ing, p e ious his o y o kidney o uppe
u e e al s ones, demog aphic and clinical cha ac e is ics.[1,2] Following a physical examina ion, all pa ien s
unde wen u ine dips ick es ing o s anda d u inalysis o de ec haema u ia.
Poin -o -Ca e Ul asonog aphy (POCUS)
Hyd oneph osis was assessed using poin -o -ca e ul asonog aphy (POCUS) wi h a cu ilinea p obe. POCUS
was pe o med by ained eme gency physicians, ul asonog aphically expe ienced clinicians o medical in e ns.
When pe o med by less expe ienced ope a o s, all indings we e e iewed by an eme gency physician. The
p esence o absence o hyd oneph osis was eco ded by he p ima y examine .
Con i ma o y imaging and Diagnosis
Non-con as helical CT (NCCT) se ed as he e e ence s anda d o de ini i e diagnosis, gi en i s high
sensi i i y and speci ici y o u e e al s ones.[1,2] When NCCT was no pe o med, kidney-u e e -bladde
(KUB) adiog aphy o ul asound indings by expe ienced eme gency physicians o u ologis s we e accep ed,
pa icula ly i s ones we e isualized a he pel iu e e ic junc ion. The inal diagnosis was made by he ea ing
eme gency physician o , when indica ed, in consul a ion wi h a u ologis .
Sco e calcula ion
A e es ablishing he inal diagnosis, he CHOKAI and STONE sco es we e calcula ed o all pa ien s. The
CHOKAI sco e anges om 0 o 11 poin s and inco po a es se en a iables: age, sex, pain du a ion, nausea o
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omi ing, his o y o enal s ones, p esence o haema u ia and hyd oneph osis on ul asonog aphy.[6,5] The
STONE sco e, o compa ison, includes sex, pain du a ion, nausea/ omi ing, haema u ia and ace. Sco es we e
eco ded in a dedica ed o m along wi h he inal diagnos ic indings o subsequen analysis. The CHOKAI
sco e c i e ia a e summa ized in (Table 1).
Table 1: CHOKAI Sco e Componen s and Assigned Values.
Pa ame e
Sco e
Age < 60 yea s
1
Age ≥ 60 yea s
0
Male
1
Female
0
Pain du a ion < 6 hou s
2
Pain du a ion 6-24 hou s
0
Pain du a ion > 24 hou s
0
Nausea
1
Vomi ing
1
None (nausea/ omi ing)
0
His o y o enal s ones (Yes)
1
His o y o enal s ones (No)
0
Hyd oneph osis on ul asound (Yes)
1
Hyd oneph osis on ul asound (No)
0
Hema u ia (Yes)
3
Hema u ia (No)
0
Ou come measu es
The p ima y ou come was he diagnos ic accu acy o he CHOKAI sco e, assessed by he a ea unde he
ecei e ope a ing cha ac e is ic (ROC) cu e (AUC). The seconda y ou come was de e mina ion o he op imal
cu -o sco e o p edic ing u e e al s ones, de ined by he poin maximizing bo h sensi i i y and speci ici y.
Sensi i i y, speci ici y, posi i e likelihood a io (LR+) and nega i e likelihood a io (LR–) we e calcula ed a
his cu -o .
Sample size calcula ion
Sample size was de e mined based on an an icipa ed AUC o 0.8 om p io li e a u e, wi h a 95% con idence
in e al (CI) wid h o ±0.05, calcula ed using he me hod o Hanley and McNeil. The equi ed minimum sample
size was 99 pa ien s.
S a is ical analysis
Con inuous a iables we e summa ized as mean ± s anda d de ia ion (SD) and ca ego ical a iables as coun s
and pe cen ages. ROC analysis was pe o med o calcula e AUC and de e mine he op imal cu -o poin .
S a is ical signi icance was se a p < 0.05.
RESULTS
A o al o 200 pa ien s me he inclusion c i e ia. The mean age was 39.4 ± 16.1 yea s and 128 pa ien s (64.3%)
we e diagnosed wi h u e e al s ones based on con i ma o y imaging.
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POCUS e ealed hyd oneph osis in 146 pa ien s (73.4%), while 53 pa ien s (26.6%) showed no e idence o
hyd oneph osis. CHOKAI sco e ca ego ies we e as ollows: mild (0–4 poin s) in34 pa ien s (17.1%), mode a e
(5–8 poin s) in 125 pa ien s (62.8%) and se e e (9–11 poin s) in 40 pa ien s (20.1%)
Recei e ope a ing cha ac e is ic (ROC) analysis showed an a ea unde he cu e (AUC) o 0.831 (95% CI:
0.771–0.880; p < 0.0001) o he CHOKAI sco e in de ec ing u e e al s ones.
A he op imal cu -o sco e o >5, he sensi i i y was 82.0% (95% CI: 74.3–88.3), speci ici y was 67.6% (95%
CI: 55.5–78.2) and he Youden Index was 0.496
Among he 71 pa ien s wi hou u e e al s ones, 36 (50.7%) we e co ec ly classi ied as below he cu -o . Among
he 128 pa ien s wi h u e e al s ones, 100 (78.1%) we e co ec ly classi ied as abo e he cu -o . CT scan esul s
showed ha 64.3% o pa ien s had posi i e indings o u e e al s ones, while 35.7% had nega i e indings.
Timing o CT imaging a ied, wi h 24% pe o med a e one week and 53% a e wo weeks om ED
p esen a ion, po en ially in luencing s one de ec ion a es (Figu e 1). The diagnos ic pe o mance cha ac e is ics
a he op imal cu -o a e p esen ed in (Table 2).
Figu e 1: Recei e Ope a ing Cha ac e is ic Cu e o he CHOKAI Sco e.
ROC cu e showing he diagnos ic pe o mance o he CHOKAI sco e o p edic ing u e e al s ones, wi h an
AUC o 0.831 (95% CI: 0.771–0.880) (Table 2).
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Table 2: ROC Analysis o he CHOKAI Sco e o he Diagnosis o U e e al S ones
CHOKAI
sco e
AUC (95% CI)
Cu -
o
Sensi i i y (95%
CI)
Speci ici y (95%
CI)
LR
+
LR
-
Youden's
index
0.831 (0.771 -
0.880)
>5
82.03 (74.3 - 88.3)
67.61 (55.5 - 78.2)
2.53
0.2
7
0.496
DISCUSSION
In his mul icen e ex e nal alida ion s udy, he CHOKAI sco e demons a ed mode a e diagnos ic pe o mance
o p edic ing u e e al s ones among pa ien s p esen ing o he eme gency depa men (ED) wi h lank o loin
pain. The a ea unde he ecei e ope a ing cha ac e is ic cu e (AUC) was 0.831, wi h accep able sensi i i y
(82.0%) bu ela i ely lowe speci ici y (67.6%) a he op imal cu -o o >5 poin s [6,7]. Ou indings sugges
ha he CHOKAI sco e may se e as a use ul sc eening ool; howe e , i has limi a ions when used as a s and-
alone me hod o de e con i ma o y imaging [6].
Hyd oneph osis as a key p edic o
Hyd oneph osis de ec ion eme ged as a c i ical ac o in he CHOKAI sco e, con ibu ing 1 o 11 poin s. In ou
coho , 73.4% o pa ien s exhibi ed hyd oneph osis, consis en wi h p io s udies emphasizing i s diagnos ic
impo ance in u e e al s ones. Howe e , ul asonog aphy is inhe en ly use -dependen and diagnos ic accu acy
a ies wi h ope a o expe ience. Some scans in ou s udy we e pe o med by medical in e ns o non- ellowship-
ained physicians, po en ially a ec ing p ecision. To mi iga e his, all indings by less expe ienced ope a o s
we e e iewed by ained eme gency physicians and a ge ed aining imp o ed o e all accu acy.
POCUS is a use ul ool o p edic ing u e e al s ones; howe e , hyd oneph osis as an isola ed inding on US
does no eliably p edic s ones and combining POCUS wi h clinical p edic ion sco es, such as in he STONE
PLUS s udy, imp o es diagnos ic pe o mance.
Timing o con i ma o y imaging
Ano he ac o in luencing esul s was he delay in CT imaging. Fo 24% o pa ien s, CT was pe o med mo e
han one week a e ED p esen a ion and o 53%, CT was done a e wo weeks. This delay may ha e led o
spon aneous s one passage, con ibu ing o alse-nega i e indings and unde es ima ion o CHOKAI sco e
pe o mance4. Despi e his, ou indings sugges ha pa ien s wi h CHOKAI sco es ≥6 poin s s ill equi e CT
con i ma ion, whe eas sco es o 0-5 poin s could po en ially allow clinicians o de e CT imaging, as none o
hese pa ien s we e ul ima ely diagnosed wi h u e e al s ones [2,3,5].
Compa ison wi h p e ious s udies
The o iginal CHOKAI s udy epo ed supe io diagnos ic accu acy compa ed wi h he STONE sco e, a ibu ed
in pa o he inclusion o hyd oneph osis as a p edic i e a iable [6]. Ou s udy suppo s his inding bu
highligh s ha ope a o a iabili y and iming o imaging may educe speci ici y in eal-wo ld ED se ings.
While CHOKAI shows p omise o s a i ying pa ien s and op imizing imaging s a egies, i should no eplace
con i ma o y adiological es s, pa icula ly in pa ien s wi h pe sis en o se e e symp oms [2,4].
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Clinical implica ions
The CHOKAI sco e may assis clinicians in p io i izing high- isk pa ien s o ea ly CT imaging while
po en ially de e ing imaging o low-sco e pa ien s, educing cumula i e adia ion exposu e and ED leng h o
s ay [2,5,6]. Howe e , app op ia e aining in POCUS is essen ial o maximize sco e accu acy and ensu e
eliable de ec ion o hyd oneph osis.
This s udy has se e al limi a ions. Fi s , i included only Omani pa ien s, which may limi he gene alizabili y o
he CHOKAI sco e o o he popula ions [6]. Second, ul asonog aphy was pe o med by ope a o s wi h a ying
le els o expe ience, including medical in e ns and non- ellowship- ained physicians, po en ially educing
diagnos ic p ecision despi e e iew by expe ienced eme gency physicians. Thi d, delayed con i ma o y CT
imaging in many cases- 24% a e one week and 53% a e wo weeks- may ha e led o spon aneous s one
passage and unde es ima ion o sensi i i y [4]. Addi ionally, we did no di ec ly compa e he CHOKAI sco e
wi h he STONE sco e in his popula ion, which could p o ide u he insigh in o i s ela i e u ili y [6]. Despi e
hese limi a ions, he s udy has no able s eng hs, including i s mul icen e design, p ospec i e da a collec ion
and eal-wo ld ED se ing, which enhance he applicabili y and ele ance o he indings o ou ine clinical
p ac ice [6,7].
CONCLUSIONS
The CHOKAI sco e demons a ed mode a e diagnos ic accu acy o p edic ing u e e al s ones in pa ien s
p esen ing wi h loin pain in he Omani eme gency depa men se ing, achie ing good sensi i i y bu only ai
speci ici y a he op imal cu -o o >5. While i may se e as a use ul adjunc in isk s a i ica ion and imaging
p io i iza ion, i should no eplace con i ma o y CT scanning. Inco po a ing CHOKAI sco ing in o a s uc u ed
diagnos ic pa hway - combined wi h clinician judgmen , imely imaging and enhanced ul asound aining-
could help op imize esou ce use while minimizing unnecessa y adia ion exposu e. Fu he p ospec i e,
mul icen e s udies in di e se popula ions a e wa an ed o e ine and alida e i s clinical u ili y.
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