Low Sensitivity of Simtomax Point of Care Test in Detection of Celiac … › praxis › Tangermann_Branchi_PO… · CONCLUSIONS: In a study of more than 1000 adults and children,

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Clinical Gastroenterology and Hepatology 2018;-:-–-

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Low Sensitivity of Simtomax Point of Care Test in Detectionof Celiac Disease in a Prospective Multicenter Study

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Paul Tangermann,* Federica Branchi,* Alice Itzlinger,* Jens Aschenbeck,‡ Stefan Schubert,§

Jochen Maul,§ Thomas Liceni,§ Andreas Schröder,k Frank Heller,¶ Wolfgang Spitz,#

Ulrich Möhler,# Ulrich Graefe,# Michael Radke,** Stefan Trenkel,** Markus Schmitt,‡‡

Christoph Loddenkemper,§§ Jan C. Preiß,* Reiner Ullrich,* Severin Daum,* Britta Siegmund,*Christian Bojarski,* and Michael Schumann*

*Department of Gastroenterology, Infectious Diseases and Rheumatology, Campus Benjamin Franklin, Charité –

Universitätsmedizin Berlin and Berlin Institute of Health, Berlin, Germany; ‡Praxis Dr. Aschenbeck, Berlin, Germany; §Praxis fürGastroenterologie am Bayerischen Platz, Berlin, Germany; kGemeinschaftspraxis Hohenzollerndamm, Berlin, Germany; ¶PraxisHeller/Mayr, Berlin, Germany; #Gastroenterologie am Mexikoplatz, Berlin, Germany; **Ernst von Bergmann Klinikum, Potsdam,Germany; ‡‡Evangelisches Krankenhaus Ludwigsfelde-Teltow, Ludwigsfelde, Germany; and §§PathoTres Praxis für Pathologieund Neuropathologie, Berlin, Germany

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BACKGROUND & AIMS:
Abbreviations used in this papdated gliadin peptide; FN, falseantitransglutaminase antibodie

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Point of care tests (POCTs) might be used to identify patients with undiagnosed celiac diseasewho require further evaluation. We performed a large multicenter study to determine theperformance of a POCT for celiac disease and assessed celiac disease prevalence in endoscopycenters.

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METHODS: 85
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We performed a prospective study of 1055 patients (888 adults; median age, 48 yrs and 167children; median age, 10 yrs) referred to 8 endoscopy centers in Germany, for various in-dications, from January 2016 through June 2017. Patients were tested for celiac disease usingSimtomax, which detects immunoglobulin (Ig)A and IgG antibodies against deamidated gliadinpeptides (DGP). Results were compared with findings from histologic analyses of duodenalbiopsies (reference standard). The primary aim was to determine the accuracy of this POCT forthe detection of celiac disease, to identify candidates for duodenal biopsy. A secondary aim wasto determine the prevalence of celiac disease in adult and pediatric populations referred foroutpatient endoscopic evaluation.

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RESULTS:
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The overall prevalence of celiac disease was 4.1%. The POCT identified individuals with celiacdisease with 79% sensitivity (95% CI, 64%–89%) and 94% specificity (95% CI, 93%–96%).Positive and negative predictive values were 37% and 99%. When we analyzed the adult andpediatric populations separately, we found the test to identify adults with celiac disease(prevalence 1.2%) with 100% sensitivity and 95% specificity. In the pediatric population (ce-liac disease prevalence 19.6%), the test produced false-negative results for 9 cases; the testtherefore identified children with celiac disease with 72% sensitivity (95% CI 53%–86%).Analyses of serologic data revealed significantly lower DGP titers in the false-negative vs thetrue-positive group.

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CONCLUSIONS:
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In a study of more than 1000 adults and children, we found the Simtomax POCT to detect celiacdisease with lower overall levels of sensitivity than expected. Although the test identifies adultswith celiac disease with high levels of sensitivity and specificity, the prevalence of celiac diseasewas as low as 1.2% among adults. The test’s lack of sensitivity might be due to the low intensityof the POCT bands and was associated with low serum DGP titers. Study ID no: DRKS00012499.

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Keywords: Noninvasive; Gluten; Gastroscopy; Diagnostic.
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er: CI, confidence interval; DGP, deami-negative; POCT, point-of-care test; tTG,

s.

© 2018 by the AGA Institute1542-3565/$36.00

https://doi.org/10.1016/j.cgh.2018.09.032

LA 5.5.0 DTD � YJCGH56103_proof � 23 November 2018 � 5:52 pm � ce CJ

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What You Need to Know

BackgroundThe diagnosis of CD can be challenging with highnumbers of undiagnosed cases nowadays. Rapid,easy-to-use POCTs are currently under investigationto uncover CD cases, showing diagnostic perfor-mance close to standard serology in previous mon-ocentric studies.

FindingsThis large multi-center-study showed an unreportedlack of sensitivity of the Simtomax-POCT. Theresulting false negative tests are linked to weaklycolored test-bands and low antibody titers.

Implications for patient careAt this stage the POCT does not qualify to be intro-duced as a screening test into routine clinicalpractice.

2 Tangermann et al Clinical Gastroenterology and Hepatology Vol. -, No. -

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Celiac disease is a chronic inflammatory disorder ofthe small bowel, characterized by an abnormal

immune response triggered by the ingestion of glutenin genetically susceptible individuals.1 It is the mostcommon chronic enteropathy in Western countrieswith an estimated prevalence up to 1% in Europe.2

Data from population screenings suggest that a largepercentage of celiac patients remains undiagnosed.3

The wide spectrum of celiac disease manifestationscauses the diagnosis to be challenging: the classicmanifestation with malabsorption syndrome, weightloss, and diarrhea represents nowadays only a smallproportion of cases, whereas many patients reportmild gastrointestinal symptoms or single-nutrientdeficiency.4 In view of this, physicians evaluatingpatients with nonspecific gastrointestinal symptomsthat are common in many functional and organicdisorders face the risk of missing a celiac disease diag-nosis.1,5 Particularly, patients referred for gastroscopyare not regularly tested for celiac disease serology,such as antitransglutaminase antibodies (tTG; sensi-tivity 95% and specificity 95%5) or deamidatedgliadin peptides antibodies (DGP; sensitivity 82%–84% and specificity 80%–99%6). Considering thereported lack of visual endoscopic markers pointingtoward the diagnosis,7 a trigger to acquire duodenalbiopsies is frequently missing. Routine duodenal bi-opsies during all gastroscopies could improve diag-nosis rates but would result in a high burden interms of costs and resources and increase the risk ofcomplications.8–10 In this setting, the availability of asimple point-of-care test (POCT) for the detection ofspecific serum antibodies would be of great value inaiding the diagnostic process. Particularly, a test withan optimal sensitivity and a reasonable specificitycould contribute to select patients with suspected ce-liac disease in whom to perform duodenal biopsies.To date, different POCTs have been evaluated aspossible screening in primary or secondary care.11–17

Simtomax (Tillotts Pharma AG, Rheinfelden,Switzerland) is a POCT developed to detect serumIgA and IgG antibodies specific for DGP.18 In severalprevious single-center studies, Simtomax was appliedto patient populations undergoing gastroscopy forboth suspected celiac disease and unspecific GI symp-toms and showed sensitivity and specificity similar toroutine tTG testing.17–23

With these premises, the aim of our study was toevaluate the sensitivity and specificity of Simtomax in aclinical endoscopy setting. Our goal was to establishwhether the accuracy of this POCT for the detection ofceliac disease is sufficient to propose its introduction inroutine endoscopic practice as a screening test to guideduodenal biopsy. A secondary aim of our study was toobtain prevalence data for celiac disease in an adult anda pediatric population referred for outpatient endoscopicevaluation.

FLA 5.5.0 DTD � YJCGH56103_proof � 2

Materials and Methods

Study Design

This prospective, investigator-initiated multicenterstudy was carried out in 8 endoscopy centers within thegreater Berlin area in Germany, including 5 adultoutpatient endoscopy services and 3 hospital-associatedendoscopy divisions, of which 1 is a tertiary center foradult gastroenterology and 2 are pediatric centers.The recruiting centers were coordinated by the Depart-ment of Gastroenterology, Infectious Diseases andRheumatology (Campus Benjamin Franklin, Charité-Universitätsmedizin Berlin).

Patients

Between January 2016 and June 2017, patientsreferred to the participating centers for gastroscopywere prospectively evaluated for participation in thestudy. The inclusion criteria were the presence ofinformed consent for participation and clinical indicationto gastroscopy. Exclusion criteria were a known diag-nosis of celiac disease, an ongoing gluten-free diet, andthe presence of bleeding disorders including the intakeof anticoagulant medications.

Point-of-Care-Test

Simtomax is a lateral-flow immunochromatographictest developed to detect IgA and IgG class DGP antibodies(Figure 1). The POCT was performed and interpretedaccording to the manufacturer0s instructions. For furtherdetails, refer to the Supplementary Methods section.

3 November 2018 � 5:52 pm � ce CJ

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web4C=FPO

Figure 1. Simtomax POCT. (A) Instructions to read test re-sults (adapted from the manufacturer’s instructions leaflet).Band A is for DGP antibodies detection, Band B is for totalIgA (presence of a visible line indicates normal IgA levels), andBand CT is a control band (absence of a visible line indicatesinvalid result). (B) Example of POCT tests with representativeresults of negative (above), positive (middle), and weaklypositive (below) POCT in 3 subjects with normal IgA levels.

- 2018 Point-of-Care Test for Celiac Disease 3

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Histology

During gastroscopy, 6 duodenal biopsy specimenswere collected from the duodenum, including 1 biopsyfrom the duodenal bulb, according to current guide-lines.1,5,24 Biopsies were fixed in buffered formalin andsent to the pathology services of the recruiting centers.According to practice standards, the specimens wereoriented and successively embedded in paraffin wax.Sections 1–2 mm thick were stained with hematoxylin-eosin and periodic acid–Schiff and evaluated by pathol-ogists blinded to the POCT result. The presence ofintraepithelial lymphocytosis, villous atrophy, and crypthyperplasia was graded according to the Marsh-Oberhuber classification.25 A prestudy briefing withparticipating pathology centers ensured adherence toadequate standards of histopathology analysis andreporting.

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Diagnosis of Celiac Disease

The diagnosis of celiac disease was confirmedor excluded based on the criteria established byinternational guidelines, namely the presence of aMarsh-graded enteropathy and positive tTG (or, inaccordance to the ACG and European Society for Pedi-atric Gastroenterology, Hepatology, and Nutritionguidelines, positive DGP antibodies in children youngerthan 2 years).5,24 In all cases with Marsh other than 0 orwith a positive POCT, tTG and/or DGP serology wereperformed. In case of discrepant results (ie, incoherence


of tTG-IgA and Marsh grade), an expert pathologistblinded to POCT results and to the site pathology reportreviewed the duodenal histology and verified quantifi-cation of intraepithelial lymphocytes by immunohisto-chemistry (CD3, CD8) and the study cliniciansre-evaluated the cases according to clinical presenta-tion. In particular, patients with Marsh lesions grade 1and negative antibody titers were not classified as celiacdisease. The DQ2/8 status and/or the clinical responseto a gluten-free diet were taken into account in thosecases remaining unclear.

Ethics

The study was approved by the Ethics Committees ofCharité Universitätsmedizin Berlin and of Brandenburg,Cottbus, Germany (protocol numbers EA4/140/15 andAS83(bB)/2016, respectively). It was conducted inaccordance with the principles of the Helsinki Declara-tion. All authors had access to the study data andreviewed and approved the final manuscript. The trialwas registered in the German Clinical Trials Register(DRKS, approved WHO Primary Register, www.drks.de,Study ID: DRKS00012499).

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Statistical Analysis

A sample size calculation was performed beforestudy start with the Software nQuery-3. It was initiallydetermined that a minimum of 560 cases were requiredto investigate the performance of the test at an esti-mated celiac disease prevalence of 5% in a setting ofadult gastroscopy services. This prevalence turned outto be overestimated, therefore an amendment to theprotocol was approved for the recruitment of furtherparticipants including children, because it was antici-pated that pediatric services have a substantially higherpercentage of celiac disease cases. Within the newstudy population of adults and children, with an esti-mated celiac disease prevalence of 3.5%, the totalsample size required was calculated as at least 988subjects (to ensure a precision of 10% for an estimatedsensitivity of 90%, with a 2-tailed confidence interval[CI] of 95%).

The diagnostic performance of the POCT wascalculated as sensitivity, specificity, and positive andnegative predictive value and reported with 95% CI.Descriptive statistics (median, range, and interquartileranges) were calculated, and chi-square or Fisher exacttest was used to compare proportions. Mann-Whitneytest was used to determine significance of tTG andDGP serology. P values were considered significantwhen <.05. Analyses were performed with the softwareGraphPad Prism version 6.0 for Mac (GraphPadSoftware, La Jolla, CA).


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http://www.drks.de

Table 1. Characteristics of Study Participants

Adults (n ¼ 888) Children (n ¼ 167) Overall (n ¼ 1055) P value

Median age, y 48 (18–87) 10 (0–18) 42 (0–87) <.0001Female/male 538/350 (61/39) 93/74 (56/44) 631/424 (60/40) nsIndication for gastroscopy

Abdominal pain/dyspepsia 542 (61) 98 (59) 640 (61) nsAnemia 28 (3) 1 (1) 29 (3) nsWeight loss/malabsorption 22 (2) 5 (3) 27 (3) nsDiarrheaa 61 (7) 9 (5) 70 (7) nsGastroesophageal reflux 183 (21) 34 (20) 217 (21) nsDysphagia 27 (3) 4 (2) 31 (3) nsObstipation — 2 (1) 2 (0.2) .025Failure to thrive — 5 (3) 5 (1) < .0001Otherb 25 (3) 9 (5) 34 (3) ns

NOTE. Data are expressed as median (range) or number (percentage).aMean stool frequency within diarrhea was 5/day for adults, 2/day for children, and 4/day overall.bOther indications included Crohn’s disease, arthralgia, esophageal varices, gastric cancer, autoimmune gastritis, endoscopy before gastric bypass/fundopli-cation, skin rash, and screened positive for Crohn0s disease by antitransglutaminase antibodies (first-degree relatives, diabetes mellitus type I, other autoimmunedisorder).


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Results

Characteristics of the Enrolled Patients

Within the study period, a total of 1097 patients wereenrolled, of whom 1055 were suitable for analysis byPOCT and gastroscopy. Characteristics of the study par-ticipants are summarized in Table 1. Among the 888adults (538 females; median age, 48 years) and the 167children (93 females; median age, 10 years), the mainindications for referral to gastroscopy were chronicabdominal pain/dyspeptic symptoms in both groups,followed by gastroesophageal reflux symptoms.

The contribution of each center to the overallrecruitment is depicted in Supplementary Figure 1. Eachof the adult gastroenterologic centers enrolled between3% and 32% of all adult participants, whereas the 2pediatric centers enrolled 19% and 81% of all children.

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Performance of the Point-of-Care Test

After collection of POCT data, the results werecompared with duodenal histology and with tTG and/orDGP antibodies titers. Figure 2 and SupplementaryFigure 2 summarize the results of the POCT toward thediagnosis of celiac disease, and Supplementary Table 1describes the approach to the unclear cases.

Apart from 8 cases of invalid POCT (0.8%), 1047POCT results were compared with the respective pa-thology reports. The POCT was found positive in 91 of1047 cases (56 adults and 35 children), of whom 34were diagnosed with celiac disease. Among the 956negative POCTs, 9 individuals were diagnosed with celiacdisease (9 false negatives [FN]). These data allowed forthe calculation of specificity and sensitivity of the POCT(Table 2). In the whole cohort, the POCT showed a good


specificity (94%; 95% CI, 93%–96%) but a suboptimalsensitivity (79%; 95% CI, 64%–89%).

When analyzing the adult and the pediatric popula-tion separately, a sensitivity and specificity of 100% and95%, respectively, were found in the adult group, whereno celiac disease cases were diagnosed among patientswith a negative POCT. Nevertheless, the 95% CI forsensitivity was considerably wide, as a consequence ofthe comparatively small number of celiac disease casesidentified in the adult population, so that the perfor-mance of the POCT was not significantly different.Sensitivity in children was as low as 72% (95% CI 53%–86%) because of the presence of 9 FN, whereas thespecificity was 91% (95% CI, 85%–95%).

All false-positive cases showed clinical characteristicssimilar to the patients with true-negative POCT results(54x Marsh 0, 3x Marsh 1, all tTG negative with normalIgA levels).

Analysis of False-Negative Results

The 9 celiac disease cases with a negative POCT werefurther analyzed to better understand the reason why FNPOCT results occurred (Table 3). Notably, all cases werefound in the same pediatric center, although it must beemphasized that this center recruited almost 5 timesmore participants than the second pediatric center(see Supplementary Table 2 for details on celiac diseaseprevalence and diagnostic performance of POCT in eachcenter). As a consequence, and because of the highprevalence of celiac disease among children, more thanhalf of all cases included in our study (25 of 43) wereidentified in this center. Importantly, FN resultswere generated by different investigators over the wholerecruiting period. As soon as the study board realized theoccurrence of FN cases, a further training session was


Figure 2. Results of the POCT integrated into the study algorithm. POCT not documented: POCT results were not documentedin the clinical report form. Biopsies unavailable: collection of biopsies was not performed.


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scheduled with the involved operators to ensure thatanalysis of POCT results was adequate. Moreover,remaining tests in the center were exchanged to a newlot. However, neither intervention affected the rate ofFNs. To identify a possible reason that contributes to aFN test result we examined histology and serology ofparticipants with FN POCTs. No significant differenceswhere observed with regards to the Marsh grading ofduodenal histology in FN cases as compared with truepositive, as shown in Supplementary Table 3. Addition-ally, no significant age difference was found between FNand true positive within the pediatric population, sug-gesting that there is no particular age cutoff predictivefor POCT failure (Supplementary Figure 3). Because thelargest pediatric center routinely determined tTG andDGP serology in children undergoing gastroscopy,serology results were compared with POCT results. Ofnote, the median DGP and tTG titers of the FN weresignificantly lower compared with the titers of thepediatric true-positive patients (Figure 3).

Celiac Disease Prevalence in EndoscopyCenters

Overall, 43 cases of celiac disease (11 in adults, 32 inchildren) were diagnosed. The identified celiac diseasecases were distributed among recruiting centers withprevalences of 0%–2.7% in the outpatient clinics, 2.1%in the adult tertiary center, and 18.4% and 22.6% in the


pediatric centers. According to our results, the preva-lence of undiagnosed celiac disease among patientsreferred to gastroscopy was 1.2% in the adult populationand 19% in children (overall prevalence, 4.1%). Detailson the prevalence of celiac disease according to symp-toms at presentations are presented in SupplementaryFigure 4. Of note, within the whole study collectiveonly 13 children and 1 adult presented to the gastros-copy appointment with celiac disease serology results,underlining the potential for a diagnostic tool that wouldguide the endoscopist in the decision to collect biopsies.

Discussion

The ability to immediately witness the result andreact accordingly makes POCTs 1 of the fastest growingsector of modern medical diagnostics. The introductionof these noninvasive, simple diagnostic tests has beenviewed as a major improvement in the approach tovarious clinical situations including celiac disease, adisease with a high prevalence but also a high number ofundiagnosed cases.3

Specifically, POCTs in the field of celiac disease mayallow guiding the decision whether to collect duodenalbiopsies during a gastroscopy, but might also respond tothe need to implement routine diagnostics in primarycare. Because POCTs are developed as screening tools toallocate patients and/or trigger confirmative follow-updiagnostics, emphasis when developing or evaluating a


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Table 2.Operative Statistics of the POCT in the Whole Cohort and in the Adult and Children Populations

Cohort CD prevalence, % Sensitivity, % Specificity, % PPV, % NPV, %

Overall n ¼ 1047 4.1 (3–5.5) 79 (64–89) 94 (93–96) 37 (28–48) 99 (98–100)Adults n ¼ 880 1.2 (0.7–2) 100 (68–100) 95 (93–96) 20 (11–33) 100 (99–100)Children n ¼ 167 19.2 (14–26) 72 (53–86) 91 (85–95) 66 (48–80) 93 (87–97)

NOTE. 95% confidence intervals are reported in brackets.CD, celiac disease; NPV, negative predictive value; POCT, point-of-care test; PPV, positive predictive value.


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POCT needs to be placed not only on the immediateavailability of the result but also on sensitivity as close aspossible to standard laboratory testing.26

Our study on the diagnostic performance of Simtomaxis so far the largest and furthermore the first multicenterstudy on this POCT. In accordance to the outlined field ofapplication of POCTs in celiac disease, our study wasdesigned to evaluate test performance in an appropri-ately sized group of patients referred to gastroscopy forvarious reasons. Within this population, the test was ableto predict celiac disease diagnosis with an overallsensitivity and specificity of 79% and 94%, respectively.

Previous studies investigating POCTs includedtTG-based tests, such as the Biocard and Celiac-Quick-Test, and DGP antibody-based tests, such as Simtomax. Acomparative study suggested the Simtomax test to besuperior for predicting celiac disease with a sensitivity of92.7% and a specificity of 85% in a large adult cohortwith high celiac disease prevalence of 13.4%,18 and100% sensitivity in other cohorts.17,21,22 Another studyby Polanco et al20 showed a sensitivity of 95.8%compared with diagnosis according to European Societyfor Pediatric Gastroenterology, Hepatology, and Nutrition

Table 3. Characteristics of Study Participants Displaying a Fals

No. Age, sex Symptoms POCT

1 9 y, F Failure to thrive, obstipation Negative2 16 y, F Abdominal pain, iron deficiency,

and known IgA deficiencyNegative

3 6 y, F Abdominal pain Negative4 1.5 y, F Failure to thrive, gastroesophageal

reflux, minor IgA deficiencyNegative

5 5 y, F Abdominal pain and diarrhea Negative6 15 y, F Diarrhea, screened tTG pos because

of diabetes mellitus type INegative

7 5 y, M Abdominal pain Negative8 12 y, F Asymptomatic, screened tTG pos

because of autoimmune thyroiditisNegativeIgA deficienc

9 10 y, M Failure to thrive Negative

NOTE. Antibody titers are reported in brackets when available: in some cases, setiters).DGP, deamidated gliadin peptides; IELs, intraepithelial lymphocytes (number/100positive; tTG, tissue transglutaminase antibodies.


criteria in a cohort of 100 pediatric patients with 48%celiac disease prevalence. A very recent study involvingSimtomax revealed a test sensitivity in the range of thestandard tTG serology.23 Contrary to these data, ourstudy showed lower diagnostic performances for thisPOCT, with a sensitivity as low as 79%. The comparablypoor performance of Simtomax observed in our studywas rather unexpected; therefore, possible factorsinfluencing these results were taken into consideration.

Although a single-center bias cannot be absolutelyexcluded, we believe this to be unlikely considering therepeated adequate instructions and feedback received bythe operators of the pediatric center. As previouslymentioned, this is the first multicenter study designed toassess the performance of this POCT. The design of ourstudy resulted in a “real world scenario” regarding 2 keyaspects: the prevalence of celiac disease was closer to thenormal celiac disease prevalence compared with previ-ous Simtomax studies2; and various operators workingin independent endoscopy centers needed to interprettest results, as opposed to single operator reading of testresults in most previous studies on Simtomax. Impor-tantly, the pediatric center, where FN were generated,

e-Negative POCT Result

Marsh IELs

tTGcutoff 10 U/mL

(antibody titers U/mL)

DGP cutoff 10 U/mL(antibody titers

U/mL)

IgA IgG IgA IgG

1 45 pos (18.8) neg (4.2) neg (2.1) neg (9.8)3A 40 neg (0.1) pos (>200) neg (0.1) pos (57.3)

3B 70 pos (187) neg (8.2) neg (4.7) pos (41.9)3A 50 neg (0.5) neg (1.2) neg (0.5) pos (13.2)

3B 50 pos (>200) pos (10.8) neg (n.a.) pos (16.5)3B 60 pos (90) pos (29) pos (12) pos (10.2)

3A 40 neg (n.a.) neg (n.a.) pos (84.3) neg (n.a.)

y3B 40 pos (40.3) pos (25.7) pos (20.9) n.a.

3B 40 pos (81.5) pos (>200) n.a. pos (>100)

rology results were reported as “positive” or “negative” (ie, without quantitative

enterocytes); n.a., not available; neg, negative; POCT, point-of-care test; pos,


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Figure 3. (A, B) Compari-son of titers of DGP anti-bodies levels in the serumof FN and true-positive(TP) participants. Cutofffor normal values was 10U/mL for both DGP IgAand IgG. Of note, 1 of 9(11%) patients with FNPOCT also had FN DGPserology (both DGP IgAand IgG <10 U/mL), ascompared with 1 of the 16POCT TP patients (6%).(C, D) Comparison ofserum tTG antibodies inthe same participants.Cutoff for normal valueswas 10 U/mL for both tTGIgA and IgG. Two of 9(22%) patients with FNPOCT also had FN tTGserology as comparedwith 1 of the 16 (6%)POCT TP patients. Me-dians are presented ashorizontal lines.


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was also the center where most celiac disease diagnoseswere made (23 out of 43 diagnoses); thus, the highprevalence of celiac disease in this subpopulation mayaccount for unmasking a previously unreported sensi-tivity problem.

Moreover, the analysis of available data on tTG andDGP serology allowed us to identify significantly lowerDGP and tTG titers in patients with FN POCT resultsas compared with those with true-positive results.Because of the technical characteristics of the test, it canbe expected that moderately elevated DGP titers mightelicit an immunochromatographic reaction resulting inbands being too faint to be reliably read as positive.In line with this argumentation, all operators involved inthis study reported frequent difficulties in interpretingresults because of the low intensity of the bands, whichmight contribute to the occurrence of FN results inpatients with low antibody titers (Figure 1B).

The evidence for a lower-than-expected sensitivityquestions the benefits of introducing this POCT intoroutine clinical practice (eg, for directing the decision toobtain duodenal biopsies). Especially in pediatric pop-ulations, where the pretest probability of celiac diseasebefore a gastroscopy is high (secondary to a limitednumber of indications for gastroscopy), this study sug-gests that the decision to perform duodenal biopsiesguided by clinical suspicion might not be inferior to theintroduction of a POCT into the diagnostic algorithm,


even in case of unavailable standard serology. Moreover,0.7% of the POCTs performed in our study wereanalyzed as “invalid,” which requires cost- and time-intensive repetition.

With regard to celiac disease prevalence in ourcohort, the 1.2% prevalence in adult endoscopy centerswas lower than what was anticipated in view of therising figures of celiac disease incidence reported inliterature.4 However, a recent German study reported a0.9% prevalence of positive tTG serology in more than12,700 children and adolescents, whereas a diagnosis ofceliac disease was already known in only 0.07%, whichcorroborates the hypothesis of a high number ofunknown cases in the population.27 Data from othercohorts suggest a celiac disease prevalence up to 5 timeshigher in children than in adults.28 In view of that, a 1.2%prevalence of undiagnosed celiac disease in the selectedpopulation of adult patients referred for gastroscopy(and 19% in children) can be considered accurate.

In conclusion, the results of our study question thebenefit of the use of Simtomax for the screening of adultpatients in the pregastroscopy setting, to identify thosewho require duodenal biopsies and reduce the numberof unnecessary histologic analyses. The multicenterdesign of the study allowed identifying a previouslyunreported lack of sensitivity. Thus, we suggest cautionbefore introducing this POCT into routine clinical prac-tice at this stage. Moreover, our data suggested that FN


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results are linked to lower DGP antibody titers. In linewith this, the operators involved in the evaluation ofPOCT results expressed the need for a stronger intensityof the colored bands to ease the interpretation of testresults and thereby to improve test sensitivity.

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Supplementary Material

Note: To access the supplementary material accom-panying this article, visit the online version of ClinicalGastroenterology and Hepatology at www.cghjournal.org,and at https://doi.org/10.1016/j.cgh.2018.09.032.

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1. Ludvigsson JF, Bai JC, Biagi F, et al. Diagnosis and manage-ment of adult coeliac disease: guidelines from the British Societyof Gastroenterology. Gut 2014;63:1210–1228.

2. Mustalahti K, Catassi C, Reunanen A, et al. The prevalence ofceliac disease in Europe: results of a centralized, internationalmass screening project. Ann Med 2010;42:587–595.

3. Ludvigsson JF, Rubio-Tapia A, van Dyke CT, et al. Increasingincidence of celiac disease in a North American population. AmJ Gastroenterol 2013;108:818–824.

4. Rampertab SD, Pooran N, Brar P, et al. Trends in the presen-tation of celiac disease. Am J Med 2006;119:355.

5. Rubio-Tapia A, Hill ID, Kelly CP, et al. ACG clinical guidelines:diagnosis and management of celiac disease. Am J Gastro-enterol 2013;108:656–676, quiz 77.

6. Volta U, Granito A, Parisi C, et al. Deamidated gliadin peptideantibodies as a routine test for celiac disease: a prospectiveanalysis. J Clin Gastroenterol 2010;44:186–190.

7. Dickey W, Hughes D. Disappointing sensitivity of endoscopicmarkers for villous atrophy in a high-risk population: implicationsfor celiac disease diagnosis during routine endoscopy. Am JGastroenterol 2001;96:2126–2218.

8. Green PH, Murray JA. Routine duodenal biopsies to excludeceliac disease? Gastrointest Endosc 2003;58:92–95.

9. Lebwohl B, Bhagat G, Markoff S, et al. Prior endoscopy in pa-tients with newly diagnosed celiac disease: a missed opportu-nity? Dig Dis Sci 2013;58:1293–1298.

10. Burger JP, Meijer JW, Wahab PJ. Routine duodenal biopsy toscreen for coeliac disease is not effective. Neth J Med 2013;71:308–312.

11. Korponay-Szabó IR, Raivio T, Laurila K, et al. Coeliac diseasecase finding and diet monitoring by point-of-care testing.Aliment Pharmacol Ther 2005;22:729–737.

12. Korponay-Szabó IR, Szabados K, Pusztai J, et al. Populationscreening for coeliac disease in primary care by district nursesusing a rapid antibody test: diagnostic accuracy and feasibilitystudy. BMJ 2007;335:1244–127.

13. Demirçeken FG, Kansu A, Kulo�glu Z, et al. Human tissuetransglutaminase antibody screening by immunochromato-graphic line immunoassay for early diagnosis of celiac disease inTurkish children. Turk J Gastroenterol 2008;19:14–21.

14. Nemec G, Ventura A, Stefano M, et al. Looking for celiac dis-ease: diagnostic accuracy of two rapid commercial assays. AmJ Gastroenterol 2006;101:1597–1600.


15. Singh P, Wadhwa N, Chaturvedi MK, et al. Validation of point-of-care testing for coeliac disease in children in a tertiary hospital innorth India. Arch Dis Child 2014;99:1004–1008.

16. Baldas V, Tommasini A, Trevisiol C, et al. Development of anovel rapid non-invasive screening test for coeliac disease. Gut2000;47:628–631.

17. Benkebil F, Combescure C, Anghel SI, et al. Diagnostic accu-racy of a new point-of-care screening assay for celiac disease.World J Gastroenterol 2013;19:5111–5117.

18. Mooney PD, Wong SH, Johnston AJ, et al. Increased detectionof celiac disease with measurement of deamidated gliadinpeptide antibody before endoscopy. Clin Gastroenterol Hepatol2015;13:1278–1284.

19. Bienvenu F, Besson Duvanel C, Seignovert C, et al. Evaluationof a point-of-care test based on deamidated gliadin peptides forceliac disease screening in a large pediatric population. Eur JGastroenterol Hepatol 2012;24:1418–1423.

20. Polanco I, Koester Weber T, Martínez-Ojinaga E, et al. Efficacyof a point-of-care test based on deamidated gliadin peptides forthe detection of celiac disease in pediatric patients. Rev EspEnferm Dig 2017;109:743–778.

21. Bienvenu F, Anghel SI, Besson Duvanel C, et al. Early diagnosisof celiac disease in IgA deficient children: contribution of apoint-of-care test. BMC Gastroenterol 2014;14:186.

22. Lau MS, Mooney P, White W, et al. ’Pre-endoscopy point of caretest (Simtomax- IgA/IgG-Deamidated Gliadin Peptide) forcoeliac disease in iron deficiency anaemia: diagnostic accuracyand a cost saving economic model. BMC Gastroenterol 2016;16:115.

23. Lau MS, Mooney PD, White WL, et al. Office-based point of caretesting (IgA/IgG-deamidated gliadin peptide) for celiac disease.Am J Gastroenterol 2018.

24. Husby S, Koletzko S, Korponay-Szabó IR, et al. European So-ciety for Pediatric Gastroenterology, Hepatology, and Nutritionguidelines for the diagnosis of coeliac disease. J Pediatr Gas-troenterol Nutr 2012;54:136–160.

25. Oberhuber G, Granditsch G, Vogelsang H. The histopathologyof coeliac disease: time for a standardized report scheme forpathologists. Eur J Gastroenterol Hepatol 1999;11:1185–1194.

26. Shaw JLV. Practical challenges related to point of care testing.Pract Lab Med 2016;4:22–29.

27. Laass MW, Schmitz R, Uhlig HH, et al. The prevalence of celiacdisease in children and adolescents in Germany. Dtsch ArzteblInt 2015;112:553–560.

28. Mariné M, Farre C, Alsina M, et al. The prevalence of coeliacdisease is significantly higher in children compared with adults.Aliment Pharmacol Ther 2011;33:477–486.

Reprint requestsAddress requests for reprints to: Michael Schumann, MD, Medizinische Klinikfür Gastroenterologie, Infektiologie und Rheumatologie, Campus BenjaminFranklin der Charité - Universitätsmedizin Berlin, Hindenburgdamm 30, 12200Berlin, Germany. e-mail: [email protected]; fax: þ49 (0)30450-514962.

Conflicts of interestThe authors disclose no conflicts.

FundingSupport including the supply of Simtomax tests was provided by TillottsPharma AG. Michael Schumann was supported by the Clinical Scientist pro-gram of the Berlin Institute of Health.

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Supplementary Methods

Point-of-Care-Test

The POCT was performed in the endoscopy centershortly before gastroscopy. Simtomax is a lateral-flowimmunochromatographic test developed to detect IgAand IgG class DGP-antibodies (Figure 1). The test isperformed with a small amount (25 mL) of capillarywhole blood from a finger prick, which is placed on a testfield and filtered so that only proteins pass through ontoa nitrocellulose membrane. A synthetic DGP is attachedto the membrane at the test site “A” for detection of IgAand IgG anti-DGP.17 At site “B,” attached antihuman IgAallows total IgA detection. A running buffer provided inthe test kit contains secondary gold-conjugated anti-bodies that bind to the patient’s antibodies: detectablecomplexes are formed at site “A” in case DGP antibodiesare present in the patient0s blood. The detection of totalIgA at site “B” serves as internal validation to identifypotential false-negative results caused by IgA deficiency,a condition associated with celiac disease.5 At the controlsite “CT,” attached goat antimouse antibodies react withthe secondary gold-conjugated antibodies of the buffer.The control line does not appear if the buffer did notdiffuse properly onto the strip; in that case the test is


considered invalid. The POCTs were performed accord-ing to the manufacturer’s instructions and were readafter at least 10 minutes of exposure time by specificallyinstructed operators. In case of a positive POCT, tTGserology was also obtained. In 1 of the pediatric centers,tTG and DGP serology was performed in all childrenreferred to gastroscopy.

Because these study results suggest CD diagnosisto be a rare outcome in an adult gastroscopy center, itwas interesting to us to identify the clinical symp-tomatology that contributed to the decision to performan endoscopy. As regards adults, CD was diagnosed in3 of 61 (5%) patients presenting with the symptom“diarrhea” making it the symptom associated with ahigher proportion of CD diagnoses, whereas in childrenthe symptoms “failure to thrive” and “unexplainedanemia” were associated with CD diagnosis in 4 out of5 cases (80%) and 1 out of 1 case (100%), respec-tively. The most prevailing symptom leading togastroscopy was abdominal pain/dyspepsia in childrenand adults. However, it was associated with CD only in18 of 98 (18%) children and 6 of 542 (1%) adults. Ofnote, in 3 cases CD was found in asymptomatic patientsscreened positive for tTG secondary to the previousdiagnosis of other autoimmune disorders. CD, celiacdisease.


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Supplementary Figure 2. Results of the POCT with listing of histology. CD, celiac disease; FP, false positive; M0-3c, Marshgrading; TN, true negative; TP, true positive.

Supplementary Figure 1. Contribution of the participatingcenters to the study (n, %).

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Supplementary Figure 3. Age distribution of pediatric CDcases according to test performance (TP vs FN). Means areshown as horizontal lines. TP, true positive.

SupplementaryFigure 4. Cases of celiacdiagnoses found stratifiedaccording to the leadingsymptom. Within thegroups “dysphagia” and“obstipation” no CDdiagnoses were made.



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Supplementary Table 1. Clinical Approach to Unclear Cases

Age, sex Symptoms POCT Marsh, (IELs)

tTG DGP

HLA GFD CD Follow-upIgA IgG IgA IgG

1.5, F Failure to thrive, minorIgA deficiency

neg 3A (50) neg (0.5) neg (1.2) neg (0.5) pos (13.2) nd Response Yes Percentile of weight:- before GFD ¼ 5- on GFD ¼ 14Histology after 2 y:

- on GFD: Marsh 01, F Weight loss, minor

IgA deficiencyneg 2 (45) neg (0.9) pos (17.8) neg (0.5) pos (12.8) neg No response No No changes in percentile of

weight while on GFD13, F Abdominal pain, gastritis neg 3A (42) neg (n.a.) neg (n.a.) neg (n.a.) neg (n.a.) nd nd No Lost to follow-up

Resolution of symptomswith proton pump inhibitors

16, F Abdominal pain, gastritis neg 3A (41) neg (n.a.) neg (n.a.) neg (n.a.) neg (n.a.) pos nd No Resolution of symptomswith proton pump inhibitors

Histology after 1 y on gluten-containing diet: Marsh 0

5, M Abdominal pain neg 3A (40) neg (n.a.) neg (n.a.) 84.3 (pos) neg (n.a.) pos Response Yes Clear improvement on generalstate of health while on GFD

Intensity of abdominal pain (mean):- before GFD: VAS 8- on GFD: VAS 2

NOTE. Antibody titers (U/mL) are reported in brackets when available: in some cases, serology results were reported as positive or negative, without quantitative titers (cutoff 10 U/mL).CD, celiac disease; DGP, deamidated gliadin peptides; FN, false negative; GFD, gluten-free diet; HLA, human leucocyte antigen (positive if HLA-DQ2 and/or DQ8 is present, negative if both alleles are absent); IELs, intra-epithelial lymphocytes (number/100 enterocytes); n.a.; nd, not done; neg, negative; POCT, point-of-care test; pos, positive; TN, true negative; tTG, tissue transglutaminase antibodies; VAS, visual analogue scale Q8.

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Supplementary Table 2. Characteristics of the ParticipatingCenters

Study center N CD cases Sensitivity, % Specificity, %

Outpatient 1 147 4 100 (40–100) 92 (85–95)Outpatient 2 285 1 100 (5–100) 99 (97–100)Outpatient 3 26 0 — 100 (84–100)Outpatient 4 171 2 100 (20–100) 95 (90–98)Outpatient 5 65 0 — 97 (87–99)Adult clinic 194 4 100 (40–100) 89 (84–93)Pediatric clinic 1 136 25 64 (43–81) 93 (86–97)Pediatric clinic 2 31 7 100 (56–100) 83 (62–95)

95% confidence intervals are reported in brackets. CD, celiac disease.

Supplementary Table 3. Stratification of FN and TP PatientsWith CD According to MarshGrading

CD patients

Marsh FN (n ¼ 9) TP (n ¼ 34) P value

1 1 (11) 4 (12) ns2 0 (0) 1 (3) ns3 8 (89) 29 (85) ns

3a 3 (33) 6 (18) ns3b 5 (56) 15 (44) ns3c 0 (0) 8 (24) ns

Data are expressed as number (%). CD, celiac disease; FN, false negative; ns;TP, true positive Q9.



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Documents

Low Sensitivity of Simtomax Point of Care Test in Detection of Celiac … › praxis › Tangermann_Branchi_PO… · CONCLUSIONS: In a study of more than 1000 adults and children,