Faecal calprotectin, an useful marker in discriminating between inflammatory bowel disease and functional gastrointestinal disorders

Fecal calprotectin, intestinal ultrasound, and their combination for the diagnosis of inflammatory bowel disease

BACKGROUND

We aimed to evaluate the diagnostic accuracy of fecal calprotectin (FC) and intestinal ultrasound (IUS), independently and in combination, as screening tools for adults with suspected IBD to reduce the number of unnecessary endoscopic procedures.

METHODS

We conducted a retrospective monocentric study that included consecutive adult patients with (i) ileocolonoscopy for suspected IBD between January 2021 and June 2023 who had either (ii) IUS and/or (iii) a FC test within 6 weeks. Bowel wall thickness (BWT) and the color Doppler signal (CDS) were evaluated for all segments. The presence of lymphadenopathy, loss of stratification, stricture, and fistula were also recorded.

RESULTS

In total, 119 patients with a median age of 32 years (IQR, 24.0-41.0) were included. The most common symptoms were abdominal pain (n = 88, 75 %) and chronic diarrhea (n = 89, 75 %). Among the 119 patients, 74 (62 %) had IUS, 101 (82 %) had a FC test, and 56 (47 %) had both. Forty patients (34 %) had a diagnosis of IBD, including 31 (26 %) with CD and 9 (8 %) with UC. By ROC curve analysis, the best threshold of FC to diagnose IBD was 117 ug/g (Se 97 %, Sp 73 %, PPV 67 %, NPV 98 %, AUC 0.88, 95 %CI [0.81; 0.94], p = 0.006). Using this threshold, only 3 % of patients were misclassified as non-IBD. Screening by measuring FC levels would result in a 48 % reduction in the number of adults requiring endoscopy. Abnomal IUS was significantly associated with a diagnosis of IBD (OR 5.6, 95 %IC [2.1;16.2], P = 0.0008). The association of a BWT>3 mm and a positive CDS was associated with a Se, Sp, PPV, and NPV of 48 %, 100 %, 100 %, and 75 %, respectively, but 52 % of patients were misclassified as non-IBD. The combination of a BWT>3 mm, CDS, and FC>117 ug/g had a Se, Sp, PPV, and NPV of 44 %, 100 %, 100 %, and 69 %, respectively. For patients with a normal IUS and FC<117 ug/g, 4 % were misclassified as non-IBD.

CONCLUSIONS

The combination of FC and IUS is a useful screening strategy to identify patients who truly require endoscopy for suspected IBD. Calprotectin is a highly effective test for ruling out IBD. Conversely, relying solely on IUS lacks the discriminative power to safely rule out IBD. However, it shows a high PPV and is a potent tool for diagnosing IBD.

Faecal calprotectin as a non-invasive marker of Crohn's disease in anal fistulas

AIM

Faecal calprotectin (FC) is a noninvasive marker that reflects intestinal inflammation with good sensitivity. A prior study indicated that FC values above 150 μg/g could distinguish between anal fistulas (AF) of cryptoglandular or Crohn's disease (CD) origin. It is hypothesized as a useful triage test to rule out CD in newly referred AF patients, thus reducing the number of ileocolonoscopies performed and optimizing treatment regimens in AF while minimizing patient discomfort as well as healthcare costs. The aim of the study was to determine the accuracy of FC in distinguishing between anal fistulas of cryptoglandular and CD origin, as well as compare characteristics in fistulas.

METHOD

Patients referred with anal fistula who had an FC measurement and either ileocolonoscopy or colonoscopy within 12 weeks were included. Demographic and clinical characteristics were registered. Area under the curve (AUC) was calculated as well as sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and overall accuracy.

RESULTS

A total of 63 patients were included (CD n = 31, 49%). FC was significantly higher in CD compared to cryptoglandular fistulas, even when CD was medically treated or had no luminal activity on endoscopy. FC ≥110 μg/g was significantly associated with CD (OR 12.5; 95% CI: 3.77-41.4) p < 0.0001. This was found by plotting a receiver operating characteristic (ROC) curve, with AUC 80.8 (95% CI: 0.6952-0.9217). Sensitivity and specificity were 0.76 and 0.80, respectively (PPV 76%, NPV 80% and accuracy 78%).

CONCLUSION

FC discriminates CD from cryptoglandular fistulas, even in medically treated CD with normal endoscopic findings.

Strategies to Distinguish Perianal Fistulas Related to Crohn's Disease From Cryptoglandular Disease: Systematic Review With Meta-Analysis

BACKGROUND

Management of perianal fistulas differs based on fistula type. We aimed to assess the ability of diagnostic strategies to differentiate between Crohn's disease (CD) and cryptoglandular disease (CGD) in patients with perianal fistulas.

METHODS

We performed a diagnostic accuracy systematic review and meta-analysis. A systematic search of electronic databases was performed from inception through February 2021 for studies assessing a diagnostic test's ability to distinguish fistula types. We calculated weighted summary estimates with 95% confidence intervals for sensitivity and specificity by bivariate analysis, using fixed effects models when data were available from 2 or more studies. The Quality Assessment of Diagnostic Accuracy Studies tool was used to assess study quality.

RESULTS

Twenty-one studies were identified and included clinical symptoms (2 studies; n=154), magnetic resonance imaging (MRI) characteristics (3 studies; n=296), ultrasound characteristics (7 studies; n=1003), video capsule endoscopy (2 studies; n=44), fecal calprotectin (1 study; n=56), and various biomarkers (8 studies; n=440). MRI and ultrasound characteristics had the most robust data. Rectal inflammation, multiple-branched fistula tracts, and abscesses on pelvic MRI and the Crohn's ultrasound fistula sign, fistula debris, and bifurcated fistulas on pelvic ultrasonography had high specificity (range, 80%-95% vs 89%-96%) but poor sensitivity (range, 17%-37% vs 31%-63%), respectively. Fourteen of 21 studies had risk of bias on at least 1 of the Quality Assessment of Diagnostic Accuracy Studies domains.

CONCLUSIONS

Limited high-quality evidence suggest that imaging characteristics may help discriminate CD from CGD in patients with perianal fistulas. Larger, prospective studies are needed to confirm these findings and to evaluate if combining multiple diagnostic tests can improve diagnostic sensitivity.

Ultrasonographic scores for ileal Crohn's disease assessment: Better, worse or the same as contrast-enhanced ultrasound?

BACKGROUND

Intestinal ultrasound (IUS) is an increasingly used non-invasive tool to evaluate Crohn's disease (CD) activity. Recently, two IUS scores that evaluate inflammatory activity have emerged: the Simple Ultrasound Activity Score for CD (SUS-CD) and the International Bowel Ultrasound Segmental Activity Score (IBUS-SAS). We aimed to compare the accuracy of SUS-CD, IBUS-SAS and contrast-enhanced ultrasound (CEUS) in predicting inflammatory activity in the terminal ileum in ileocolonoscopy in CD patients.

METHODS

Retrospective study including all consecutive CD patients submitted to IUS with CEUS directed to the terminal ileum performed by a single operator between April 2016 and March 2020. Segmental SUS-CD and IBUS-SAS were calculated. A time-intensity curve of the contrast bowel wall enhancement was created with measurement of peak intensity using CEUS. The CD endoscopic activity in ileocolonoscopy was graded by Simple Endoscopic Score for CD (SES-CD) as inactive (SES-CD < 7) or active (SES-CD ≥ 7).

RESULTS

Fifty patients were included, 54.0% were female, with mean age of 34 ± 12 years, and most had isolated ileal disease (60.0%), and a nonstricturing, nonpenetrating behaviour (44.0%). Most of the patients (60.0%) had active endoscopic disease (SES-CD ≥ 7). SUS-CD and IBUS-SAS were not different between patients with active or inactive endoscopic disease (p = 0.15; 0.57, respectively), having a poor accuracy to correlate endoscopic activity (area under de curve (AUC) 0.62; 0.55, respectively). Peak intensity in CEUS was significantly different in patients with active or inactive endoscopic disease (p = 0.004), having a good accuracy to correlate endoscopic activity (AUC 0.80).

CONCLUSION

Unlike CEUS, SUS-CD and IBUS-SAS were not able to accurately correlate endoscopic activity in terminal ileum in CD. Therefore, CEUS is a non-invasive emerging method that should be increasingly integrated in the ultrasonographic evaluation of CD patients.

Calprotectin: from biomarker to biological function

The incidence of inflammatory bowel diseases (IBD) emerged with Westernisation of dietary habits worldwide. Crohn's disease and ulcerative colitis are chronic debilitating conditions that afflict individuals with substantial morbidity and challenge healthcare systems across the globe. Since identification and characterisation of calprotectin (CP) in the 1980s, faecal CP emerged as significantly validated, non-invasive biomarker that allows evaluation of gut inflammation. Faecal CP discriminates between inflammatory and non-inflammatory diseases of the gut and portraits the disease course of human IBD. Recent studies revealed insights into biological functions of the CP subunits S100A8 and S100A9 during orchestration of an inflammatory response at mucosal surfaces across organ systems. In this review, we summarise longitudinal evidence for the evolution of CP from biomarker to rheostat of mucosal inflammation and suggest an algorithm for the interpretation of faecal CP in daily clinical practice. We propose that mechanistic insights into the biological function of CP in the gut and beyond may facilitate interpretation of current assays and guide patient-tailored medical therapy in IBD, a concept warranting controlled clinical trials.

Usefulness of complementary test in the study of patients with chronic abdominal pain

INTRODUCTION

Chronic abdominal pain (CAP) in children is a symptom that frequently leads to a visit to the paediatrician, which affects family life and occasionally requires the need to perform diagnostic studies (DS). The objective was to carry out a qualitative, quantitative, and economic analysis on the tests requested.

MATERIAL AND METHODS

An observational, prospective and multicentre study was conducted that included children between 4-15 years old affected by CAP. The difference between organic and functional disorders was taken into account. The following variables were collected: history, warning signs and symptoms, DS, and the cost of these.

RESULTS

The study included 235 children with CAP (Age; mean 9.7 ± 2.7 SD). The large majority (79%) were functional disorders and 21% organic disorders. Almost half of the patients had some warning sign or symptom, but urinary symptoms were only associated with organic disorders. The abdominal ultrasound, faecal parasites, breath test, and endoscopy were the most associated with organic disorders. There was a difference between the costs of the DS according to each centre. The total economic cost was 52,490.80 euros, with 195 euros per patient for functional disorders and 306 euros for organic disorders.

CONCLUSION

Signs and symptoms of alarm in CAP were very frequent, but had low discriminative capacity. The abdominal ultrasound and faecal parasites are innocuous DS, and could be useful as a first level study. The endoscopy and the breath test were the most discriminative of organic disease. The economic cost of DS arising from the diagnosis of exclusion in CAP was high.

Calprotectin in inflammatory bowel disease

The term IBD is usually used for referring to a group of inflammatory gastro-intestinal diseases (mainly Crohn's disease and ulcerative colitis). Accordingly, IBD arises as a result of inappropriate immune response to intestinal commensal organisms among genetically susceptible individuals. Performing colonoscopy and histopathologic evaluation on an inflamed bowel biopsy specimen are currently considered as gold standards for diagnosis and management of IBD. Correspondingly, these techniques are known to be invasive and costly. In recent decades, fecal calprotectin, as a biomarker, has received much attention for the diagnosis and non-invasive management of IBD. Up to now, many studies have investigated the efficacy of fecal calprotectin in the areas of IBD differentiation from IBS, prediction of endoscopic and histologic activities of IBD and prediction of disease recurrence. Although some of these studies have reported promising results, some others have shown significant limitations. Therefore, in this paper, we reviewed the most interesting ones of these studies after a brief discussion of the laboratory measurement of fecal calprotectin. Moreover, we attempted to provide an answer for the question of whether fecal-calprotectin could be considered as a potential surrogate marker for colonoscopy.

Endoscopy in inflammatory bowel diseases during the COVID-19 pandemic and post-pandemic period

The coronavirus disease 2019 (COVID-19) pandemic is changing the management of many chronic diseases, including that of patients with inflammatory bowel diseases (IBD). In particular, the performance of routine endoscopy is temporarily suspended, and only emergency endoscopy is allowed in many countries where severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has spread. We highlight different scenarios in which endoscopy should still be performed urgently in patients with IBD, as well as recommendations regarding the use of personal protective equipment. We suggest a pathway for performing safe endoscopy and discuss the potential risks of postponing endoscopy in IBD. Finally, we propose a post-pandemic plan for access to endoscopy.

Use of biomarkers in inflammatory bowel disease

There are many useful biomarkers for initial diagnosis and the management of inflammatory bowel disease. Serologic biomarkers have been traditionally used because they are widely disposable, but recently faecal biomarkers, especially faecal calprotectin, have acquired great importance as they have shown to be more precise when establishing suspicion of the disease and also as predictors of mucosal healing or persistence of inflammatory activity. Faecal calprotectin is a good tool for predicting abnormal endoscopic studies, but has limited specificity because its levels can be altered in many digestive diseases presenting with similar symptoms. The precision of faecal calprotectin is higher when associated with other altered parameters, especially with C-reactive protein, or with clinical scores of inflammatory activity. Finally, there are many new generation serologic and faecal biomarkers. Despite there not being much evidence about these yet, some of them have shown promising results in different studies.