Faecal calprotectin to detect inflammatory bowel disease: a systematic review and exploratory meta-analysis of test accuracy

Dietary inflammatory potential, genetic predisposition, and incidence of Crohn's disease and ulcerative colitis

BACKGROUND

Evidence for a potential link between dietary inflammatory potential and inflammatory bowel disease is limited, and the moderating role of genetic susceptibility remains to be assessed.

OBJECTIVE

To evaluate energy-adjusted dietary inflammatory index (E-DII) for the associations with incident Crohn's disease (CD) and ulcerative colitis (UC) and the role of genetic susceptibility.

METHODS

A total of 205,706 UK Biobank participants who were aged 39-72 years and had no known CD or UC at baseline (2006-2010) were included. The E-DII score was calculated based on energy-adjusted average intakes of 33 food or nutrient items derived from up to five 24-hour dietary recalls. Multivariable Cox regression models were used estimate hazard ratios (HRs) with 95% confidence interval (CI) for incident CD and UC.

RESULTS

During a median 12.3 years of follow-up, 382 incident CD and 798 incident UC cases were ascertained. A higher E-DII score was not associated with risk of CD (HR Q4 VS. Q1 = 1.28, 95% CI: 0.94-1.74; P-trend = 0.09) or UC (HR Q4 VS. Q1 = 1.10, 95% CI: 0.90-1.36; P-trend = 0.17). There was an interaction between the E-DII and the polygenic risk score (PRS) for CD on incident CD (P-interaction = 0.023), with an association only among participants with a high PRS (HR Q4 VS. Q1 = 1.64, 95% CI: 1.03-2.61) (P-interaction = 0.023). As compared with the participants with a low PRS for CD and a low E-DII score, participants with high levels of both scores had a particularly higher risk of CD (HR = 3.12; 95% CI: 1.74-5.60).

CONCLUSIONS

The association of dietary inflammatory potential with incident CD appears to be amplified by high genetic susceptibility to CD.

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.

Unravelling metabolite-microbiome interactions in inflammatory bowel disease through AI and interaction-based modelling

Inflammatory Bowel Diseases (IBDs) are chronic inflammatory disorders of the gastrointestinal tract and colon affecting approximately 7 million individuals worldwide. The knowledge of specific pathology and aetiological mechanisms leading to IBD is limited, however a reduced immune system, antibiotic use and reserved diet may initiate symptoms. Dysbiosis of the gut microbiome, and consequently a varied composition of the metabolome, has been extensively linked to these risk factors and IBD. Metagenomic sequencing and liquid-chromatography mass spectrometry (LC-MS) of N = 220 fecal samples by Fransoza et al., provided abundance data on microbial genera and metabolites for use in this study. Identification of differentially abundant microbes and metabolites was performed using a Wilcoxon test, followed by feature selection of random forest (RF), gradient-boosting (XGBoost) and least absolute shrinkage operator (LASSO) models. The performance of these features was then validated using RF models on the Human Microbiome Project 2 (HMP2) dataset and a microbial community (MICOM) model was utilised to predict and interpret the interactions between key microbes and metabolites. The Flavronifractor genus and microbes of the families Lachnospiraceae and Oscillospiraceae were found differential by all models. Metabolic pathways commonly influenced by such microbes in IBD were CoA biosynthesis, bile acid metabolism and amino acid production and degradation. This study highlights distinct interactive microbiome and metabolome profiles within IBD and the highly potential pathways causing disease pathology. It therefore paves way for future investigation into new therapeutic targets and non-invasive diagnostic tools for IBD.

Dysbiotic signatures and diagnostic potential of gut microbial markers for inflammatory bowel disease in Korean population

Fecal samples were collected from 640 individuals in Korea, including 523 patients with IBD (223 with Crohn's disease [CD] and 300 with ulcerative colitis [UC]) and 117 healthy controls. The samples were subjected to cross-sectional gut metagenomic analysis using 16 S rRNA sequencing and bioinformatics analysis. Patients with IBD, particularly those with CD, exhibited significantly lower alpha diversities than the healthy subjects. Differential abundance analysis revealed dysbiotic signatures, characterized by an expansion of the genus Escherichia-Shigella in patients with CD. Functional annotations showed that functional pathways related to bacterial pathogenesis and production of hydrogen sulfide (H2S) were strongly upregulated in patients with CD. A dysbiosis score, calculated based on functional characteristics, highly correlated with disease severity. Markers distinguishing between healthy subjects and patients with IBD showed accurate classification based on a small number of microbial taxa, which may be used to diagnose ambiguous cases. These findings confirm the taxonomic and functional dysbiosis of the gut microbiota in patients with IBD, especially those with CD. Taxa indicative of dysbiosis may have significant implications for future clinical research on the management and diagnosis of IBD.

Diagnosis and management of inflammatory bowel disease

Inflammatory bowel disease (IBD) is a chronic and relapsing immune-mediated disease of the gastrointestinal tract with a gradually increasing global incidence and prevalence. A prolonged course of IBD leads to a decline in patient quality of life and the creation of a substantial economic burden on society. Owing to the lack of specific diagnostic markers, the diagnosis of IBD still needs a gold standard based on a combination of clinical manifestations, imaging, laboratory, and endoscopic results. Accordingly, the current goals of IBD treatment are to alleviate clinical symptoms and reduce recurrence rates. Therefore, it is imperative to develop a standard set of procedures to diagnose and treat IBD. In this review, we summarize prominent and emerging studies, outline classical and contemporary approaches to diagnosing and managing IBD, and integrate multiple guidelines. Furthermore, we propose the possibility of establishing an early and comprehensive diagnostic workflow and personalized management strategy in the future. We aim to enhance the quality and standardization of diagnostic and treatment procedures for IBD.

Hospitalization Rates for Inflammatory Bowel Disease Are Decreasing Over Time: A Population-based Cohort Study

BACKGROUND

Recent advances in the management of inflammatory bowel disease (IBD) striving for new treatment targets may have decreased rates of hospitalization for flares. We compared all-cause, IBD-related, and non-IBD-related hospitalizations while accounting for the rising prevalence of IBD.

METHODS

Population-based, administrative health care databases identified all individuals living with IBD in Alberta between fiscal year 2002 and 2018. Hospitalization rates (all-cause, IBD-related, and non-IBD-related) were calculated using the prevalent Alberta IBD population. Hospitalizations were stratified by disease type, age, sex, and metropolitan status. Data were age and sex standardized to the 2019 Canadian population. Log-linear models calculated Average Annual Percentage Change (AAPC) in hospitalization rates with associated 95% confidence intervals (CIs).

RESULTS

From 2002-2003 to 2018-2019, all-cause hospitalization rates decreased from 36.57 to 16.72 per 100 IBD patients (AAPC, -4.18%; 95% CI, -4.69 to -3.66). Inflammatory bowel disease-related hospitalization rate decreased from 26.44 to 9.24 per 100 IBD patients (AAPC, -5.54%; 95% CI, -6.19 to -4.88). Non-IBD-related hospitalization rate decreased from 10.13 to 7.48 per 100 IBD patients (AAPC, -1.82%; 95% CI, -2.14 to -1.49). Those over 80 years old had the greatest all-cause and non-IBD-related hospitalization rates. Temporal trends showing decreasing hospitalization rates were observed across age, sex, IBD type, and metropolitan status.

CONCLUSIONS

Hospitalization rates are decreasing for all-cause, IBD-related, and non-IBD-related hospitalizations. Over the past 20 years, the care of IBD has transitioned from hospital-based care to ambulatory-centric IBD management.

Diagnostic value of fecal calprotectin in primary care patients with gastrointestinal symptoms: A retrospective Swedish cohort study

Aims

To investigate the diagnostic accuracy of fecal calprotectin (FC) for inflammatory bowel disease (IBD) and organic gastrointestinal disease (OGID) in primary care. To examine the association with demographic factors, symptoms and concomitant medical therapy.

Methods

A retrospective analysis of data on all semiquantitative FC tests from individuals ≥18 years conducted in primary care in Östergötland County in 2010. A 5-year follow-up with inclusion of new gastrointestinal diagnoses.

Results

A total of 1293 eligible patients were included. IBD was found in 8.8% and other OGID in 30.8% of patients with positive FC. Positive FC was associated with diarrhea, age >60 years, duration <3 months, use of nonsteroidal anti-inflammatory drug (NSAID), and proton pump inhibitor (PPI). Predictors of IBD were positive FC, diarrhea, rectal bleeding, and male sex; predictors of OGID positive FC, age >35 years, abnormal clinical findings, and duration <3 months. FC yielded the highest sensitivity and negative predictive value compared with demographic factors, symptoms, and duration. Use of NSAID and PPI showed a marginal increase in the sensitivity, positive predictive value, and decrease in the specificity of FC. Within 5 years, 4.0% had a new gastrointestinal diagnosis among patients with positive FC (0.6% IBD).

Conclusions

FC reliably rules out IBD and contradicts the presence of other OGID in primary care patients. Positive FC test together with other predictors, such as diarrhea, rectal bleeding, short duration, or age >35 years, should encourage a prioritized investigation. Use of NSAID, PPI, and ASA may affect the diagnostic accuracy of FC for IBD and OGID.

Pro-Inflammatory Diet Is Correlated with High Veillonella rogosae, Gut Inflammation and Clinical Relapse of Inflammatory Bowel Disease

Inflammatory bowel diseases (IBD) are chronic conditions arising from an intricate interplay of genetics and environmental factors, and are associated with gut dysbiosis, inflammation, and gut permeability. In this study, we investigated whether the inflammatory potential of the diet is associated with the gut microbiota profile, inflammation, and permeability in forty patients with IBD in clinical remission. The dietary inflammatory index (DII) score was used to assess the inflammatory potential of the diet. The fecal microbiota profile was analyzed using 16SrRNA (V3-V4) gene sequencing, while fecal zonulin and calprotectin levels were measured with enzyme-linked immunosorbent assays. We found a positive correlation between the DII score and elevated calprotectin levels (Rho = 0.498; p = 0.001), but not with zonulin levels. Although α- and β-diversity did not significantly differ across DII quartiles, the most pro-inflammatory diet group exhibited a higher fecal abundance of Veillonella rogosae (p = 0.026). In addition, the abundance of some specific bacteria sequences showed an exponential behavior across DII quartiles and a correlation with calprotectin or zonulin levels (p ≤ 0.050). This included a positive correlation between sq702. Veillonella rogosae and fecal calprotectin levels (Rho = 0.419, p = 0.007). DII, calprotectin, and zonulin levels were identified as significant predictors of 6-month disease relapse (p ≤ 0.050). Our findings suggest a potential relationship of a pro-inflammatory diet intake with Veillonella rogosae and calprotectin levels in IBD patients in clinical remission, which may contribute to disease relapse.

Leucine-Rich Alpha-2 Glycoprotein Is a Reliable Serum Biomarker for Evaluating Clinical and Endoscopic Disease Activity in Inflammatory Bowel Disease

BACKGROUND

Leucine-rich alpha-2 glycoprotein (LRG) is a novel serum biomarker for inflammation in inflammatory bowel disease (IBD). This prospective study aimed to compare the value of LRG with C-reactive protein (CRP) and fecal calprotectin for evaluating clinical and endoscopic disease activity in patients with IBD.

METHODS

At entry, clinical and endoscopic disease activity was assessed in 267 patients with IBD (ulcerative colitis [UC] 203; Crohn's disease [CD] 64), and the levels of LRG, CRP and fecal calprotectin were measured. The accuracy of the biomarkers for the detection of clinical and endoscopic disease activity was determined by the area under the receiver operating characteristic curve.

RESULTS

Leucine-rich alpha-2 glycoprotein showed a significant relationship with the clinical and endoscopic severity in both UC and CD (both diseases, P < .0001). In the clinical assessment of UC, the accuracy of LRG was significantly higher than that of CRP (0.73 vs 0.63; P < .001). In the endoscopic assessment of UC, the accuracy of LRG was significantly higher than that of CRP (P = .01), but it was significantly lower than that of fecal calprotectin (P = .009; LRG, 0.80; CRP, 0.72; fecal calprotectin, 0.91). In the clinical and endoscopic assessment of CD, the accuracy was not significantly different between the biomarkers (clinical activity: LRG, 0.71; CRP, 0.64; fecal calprotectin, 0.66; in endoscopic activity: LRG, 0.79; CRP, 0.78; fecal calprotectin, 0.81).

CONCLUSIONS

Leucine-rich alpha-2 glycoprotein is a reliable serum biomarker for the assessment of clinical and endoscopic disease activity in patients with IBD. It can be an alternative to CRP for the assessment of UC.

Colonocyte keratin 7 is expressed de novo in inflammatory bowel diseases and associated with pathological changes and drug-resistance

The clinical course of IBD, characterized by relapses and remissions, is difficult to predict. Initial diagnosis can be challenging, and novel disease markers are needed. Keratin 7 (K7) is a cytoskeletal intermediate filament protein not expressed in the colonic epithelium but has been reported in IBD-associated colorectal tumors. Our aim was to analyze whether K7 is expressed in chronic colonic inflammatory diseases and evaluate its potential as a novel biomarker. K7 was analyzed in two patient cohorts using immunohistochemistry-stained colon samples and single-cell quantitative digital pathology methods. K7 was correlated to pathological changes and clinical patient characteristics. Our data shows that K7 is expressed de novo in the colonic epithelium of ulcerative colitis and Crohn's disease IBD patients, but not in collagenous or lymphocytic colitis. K7 mRNA expression was significantly increased in colons of IBD patients compared to controls when assessed in publicly available datasets. While K7 increased in areas with inflammatory activity, it was not expressed in specific crypt compartments and did not correlate with neutrophils or stool calprotectin. K7 was increased in areas proximal to pathological alterations and was most pronounced in drug-resistant ulcerative colitis. In conclusion, colonic epithelial K7 is neo-expressed selectively in IBD patients and could be investigated for its potential as a disease biomarker.

Inflammatory bowel disease biomarkers

Inflammatory bowel disease (IBD) is characterized as chronic inflammation in the gastrointestinal tract, which includes two main subtypes, Crohn's disease and ulcerative colitis. Endoscopy combined with biopsy is the most effective way to establish IBD diagnosis and disease management. Imaging techniques have also been developed to monitor IBD. Although effective, the methods are expensive and invasive, which leads to pain and discomfort. Alternative noninvasive biomarkers are being explored as tools for IBD prognosis and disease management. This review focuses on novel biomarkers that have emerged in recent years. These serological biomarkers and microRNAs could potentially be used for disease management in IBD, thereby decreasing patient discomfort and morbidity.

Multifunctional Role of S100 Protein Family in the Immune System: An Update

S100 is a broad subfamily of low-molecular weight calcium-binding proteins (9–14 kDa) with structural similarity and functional discrepancy. It is required for inflammation and cellular homeostasis, and can work extracellularly, intracellularly, or both. S100 members participate in a variety of activities in a healthy cell, including calcium storage and transport (calcium homeostasis). S100 isoforms that have previously been shown to play important roles in the immune system as alarmins (DAMPs), antimicrobial peptides, pro-inflammation stimulators, chemo-attractants, and metal scavengers during an innate immune response. Currently, during the pandemic, it was found that several members of the S100 family are implicated in the pathophysiology of COVID-19. Further, S100 family protein members were proposed to be used as a prognostic marker for COVID-19 infection identification using a nasal swab. In the present review, we compiled the vast majority of recent studies that focused on the multifunctionality of S100 proteins in the complex immune system and its associated activities. Furthermore, we shed light on the numerous molecular approaches and signaling cascades regulated by S100 proteins during immune response. In addition, we discussed the involvement of S100 protein members in abnormal defense systems during the pathogenesis of COVID-19.

Global Hospitalization Trends for Crohn's Disease and Ulcerative Colitis in the 21st Century: A Systematic Review With Temporal Analyses

BACKGROUND & AIMS

The evolving epidemiologic patterns of inflammatory bowel disease (IBD) throughout the world, in conjunction with advances in therapeutic treatments, may influence hospitalization rates of IBD. We performed a systematic review with temporal analysis of hospitalization rates for IBD across the world in the 21st century.

METHODS

We systematically reviewed Medline and Embase for population-based studies reporting hospitalization rates for IBD, Crohn's disease (CD), or ulcerative colitis (UC) in the 21st century. Log-linear models were used to calculate the average annual percentage change (AAPC) with associated 95% confidence intervals (95% CIs). Random-effects meta-analysis pooled country-level AAPCs. Data were stratified by the epidemiologic stage of a region: compounding prevalence (stage 3) in North America, Western Europe, and Oceania vs acceleration of incidence (stage 2) in Asia, Eastern Europe, and Latin America vs emergence (stage 1) in developing countries.

RESULTS

Hospitalization rates for a primary diagnosis of IBD were stable in countries in stage 3 (AAPC, -0.13%; 95% CI, -0.72 to 0.97), CD (AAPC, 0.20%; 95% CI, -1.78 to 2.17), and UC (AAPC, 0.02%; 95% CI, -0.91 to 0.94). In contrast, hospitalization rates for a primary diagnosis were increasing in countries in stage 2 for IBD (AAPC, 4.44%; 95% CI, 2.75 to 6.14), CD (AAPC, 8.34%; 95% CI, 4.38 to 12.29), and UC (AAPC, 3.90; 95% CI, 1.29 to 6.52). No population-based studies were available for developing regions in stage 1 (emergence).

CONCLUSIONS

Hospitalization rates for IBD are stabilizing in countries in stage 3, whereas newly industrialized countries in stage 2 have rapidly increasing hospitalization rates, contributing to an increasing burden on global health care systems.

Comparing outcomes from tailored meta-analysis with outcomes from a setting specific test accuracy study using routine data of faecal calprotectin testing for inflammatory bowel disease

Background

Meta-analyses of test accuracy studies may provide estimates that are highly improbable in clinical practice. Tailored meta-analysis produces plausible estimates for the accuracy of a test within a specific setting by tailoring the selection of included studies compatible with a specific setting using information from the target setting. The aim of this study was to validate the tailored meta-analysis approach by comparing outcomes from tailored meta-analysis with outcomes from a setting specific test accuracy study.

Methods

A retrospective cohort study of primary care electronic health records provided setting-specific data on the test positive rate and disease prevalence. This was used to tailor the study selection from a review of faecal calprotectin testing for inflammatory bowel disease for meta-analysis using the binomial method and the Mahalanobis distance method. Tailored estimates were compared to estimates from a study of test accuracy in primary care using the same routine dataset.

Results

Tailoring resulted in the inclusion of 3/14 (binomial method) and 9/14 (Mahalanobis distance method) studies in meta-analysis. Sensitivity and specificity from tailored meta-analysis using the binomial method were 0.87 (95% CI 0.77 to 0.94) and 0.65 (95% CI 0.60 to 0.69) and 0.98 (95% CI 0.83 to 0.999) and 0.68 (95% CI 0.65 to 0.71), respectively using the Mahalanobis distance method. The corresponding estimates for the conventional meta-analysis were 0.94 (95% CI 0.90 to 0.97) and 0.67 (95% CI 0.57 to 0.76) and for the FC test accuracy study of primary care data 0.93 (95%CI 0.89 to 0.96) and 0.61 (95% CI 0.6 to 0.63) to detect IBD at a threshold of 50 μg/g. Although the binomial method produced a plausible estimate, the tailored estimates of sensitivity and specificity were not closer to the primary study estimates than the estimates from conventional meta-analysis including all 14 studies.

Conclusions

Tailored meta-analysis does not always produce estimates of sensitivity and specificity that lie closer to the estimates derived from a primary study in the setting in question. Potentially, tailored meta-analysis may be improved using a constrained model approach and this requires further investigation.

Diagnostic Utility of Non-invasive Tests for Inflammatory Bowel Disease: An Umbrella Review

BACKGROUND

This study aims to consolidate evidence from published systematic reviews and meta-analyses evaluating the diagnostic performances of non-invasive tests for inflammatory bowel disease (IBD) in various clinical conditions and age groups.

METHODS

Two independent reviewers systematically identified and appraised systematic reviews and meta-analyses assessing the diagnostic utility of non-invasive tests for IBD. Each association was categorized as adults, children, and mixed population, based on the age ranges of patients included in the primary studies. We classified clinical scenarios into diagnosis, activity assessment, and predicting recurrence.

RESULTS

In total, 106 assessments from 43 reviews were included, with 17 non-invasive tests. Fecal calprotectin (FC) and fecal lactoferrin (FL) were the most sensitive for distinguishing IBD from non-IBD. However, anti-neutrophil cytoplasmic antibodies (ANCA) and FL were the most specific for it. FC and FL were the most sensitive and specific tests, respectively, to distinguish IBD from irritable bowel syndrome (IBS). Anti-Saccharomyces cerevisiae antibodies (ASCA), IgA, were the best test to distinguish Crohn's disease (CD) from ulcerative colitis (UC). Interferon-γ release assay was the best test to distinguish CD from intestinal tuberculosis (ITB). Ultrasound (US) and magnetic resonance enterography (MRE) were both sensitive and specific for disease activity, along with the high sensitivity of FC. Small intestine contrast ultrasonography (SICUS) had the highest sensitivity, and FC had the highest specificity for operative CD recurrence.

CONCLUSION

In this umbrella review, we summarized the diagnostic performance of non-invasive tests for IBD in various clinical conditions and age groups. Clinicians can use the suggested non-invasive test depending on the appropriate clinical situation in IBD patients.

Screening for gastrointestinal and pancreatic diseases

Diagnosis of chronic gastrointestinal and pancreatic diseases is challenging because patients generally present with nonspecific symptoms, such as abdominal pain and chronic diarrhea, some of which can last for many years. Although stool assays are more sensitive than serum assays, the former has unique limitations that healthcare providers should be aware of. One algorithm to screen for chronic gastrointestinal and pancreatic issues is to perform stool testing to assess inflammatory, watery (osmotic) and malabsorptive conditions. This chapter will discuss several stool-based screening tests, the major disorders they screen for and clinical performance. Sections on assay and sample limitations are also included. Stool testing can provide valuable diagnostic, prognostic and treatment response information if both the laboratory and clinician understand the benefits and limitations of these assays.

'Diagnostic downshift': clinical and system consequences of extrapolating secondary care testing tactics to primary care

Numerous drivers push specialist diagnostic approaches down to primary care ('diagnostic downshift'), intuitively welcomed by clinicians and patients. However, primary care's different population and processes result in under-recognised, unintended consequences. Testing performs poorer in primary care, with indication creep due to earlier, more undifferentiated presentation and reduced accuracy due to spectrum bias and the 'false-positive paradox'. In low-prevalence settings, tests without near-100% specificity have their useful yield eclipsed by greater incidental or false-positive findings. Ensuing cascades and multiplier effects can generate clinician workload, patient anxiety, further low-value tests, referrals, treatments and a potentially nocebic population 'disease' burden of unclear benefit. Increased diagnostics earlier in pathways can burden patients and stretch general practice (GP) workloads, inducing downstream service utilisation and unintended 'market failure' effects. Evidence is tenuous for reducing secondary care referrals, providing patient reassurance or meaningfully improving clinical outcomes. Subsequently, inflated investment in per capita testing, at a lower level in a healthcare system, may deliver diminishing or even negative economic returns. Test cost poorly represents 'value', neglecting under-recognised downstream consequences, which must be balanced against therapeutic yield. With lower positive predictive values, more tests are required per true diagnosis and cost-effectiveness is rarely robust. With fixed secondary care capacity, novel primary care testing is an added cost pressure, rarely reducing hospital activity. GP testing strategies require real-world evaluation, in primary care populations, of all downstream consequences. Test formularies should be scrutinised in view of the setting of care, with interventions to focus rational testing towards those with higher pretest probabilities, while improving interpretation and communication of results.

Fecal Leukocyte Esterase, an Alternative Biomarker to Fecal Calprotectin in Inflammatory Bowel Disease: A Pilot Series

Background and Aims

Fecal calprotectin (FC) is a noninvasive biomarker used in inflammatory bowel disease (IBD) management and risk stratification of nonspecific gastrointestinal symptoms. Leukocyte esterase is an inexpensive and widely available point-of-care inflammatory marker present on urinalysis test strips. We aim to assess the diagnostic accuracy of fecal leukocyte esterase (FLE) relative to FC and endoscopy and demonstrate its use as an alternative biomarker for IBD.

Methods

In this prospective cohort study, 70 patients who had FC ordered as part of standard clinical care also received FLE testing. FLE levels were compared with various FC cutoff values and endoscopy and pathology findings as the gold standard.

Results

As the FC cutoff increased from 50 to 500 μg/g, FLE sensitivity increased from 67% to 95% while the specificity decreased from 86% to 76%. The area under the receiver operating characteristic (AUROC) curve increased from 0.79 to 0.90. An FLE of ≥1+ had the best test characteristics. Among patients who underwent endoscopic evaluation, FLE demonstrated an identical sensitivity (75%) and specificity (86%) to FC in predicting endoscopic inflammation. AUROC was 0.80 for FLE and 0.85 for FC with an optimal cutoff of ≥2+ and 301 μg/g, respectively. When used to distinguish between patients with active IBD and no/inactive IBD, FLE had a sensitivity of 84% and specificity of 90%, comparable with the 84% and 83%, respectively, of FC. AUROC was 0.88 for FLE and 0.91 for FC with an optimal cutoff of ≥2+ and 145 μg/g, respectively.

Conclusion

FLE demonstrates adequate correlation and comparable accuracy with FC in predicting endoscopic inflammation and distinguishing between patients with active vs inactive IBD.

Faecal calprotectin testing in UK general practice: a retrospective cohort study using The Health Improvement Network database

BACKGROUND

Faecal calprotectin (FC) testing to detect inflammatory bowel disease (IBD) was recommended for use in UK general practice in 2013. The actual use of FC testing following the national recommendations is unknown.

AIM

To characterise the use of FC testing for IBD in UK general practice.

DESIGN AND SETTING

A retrospective cohort study of routine electronic patient records from The Health Improvement Network database from UK general practice.

METHOD

The study included 6 965 853 adult patients (aged ≥18 years), between 2006 and 2016. FC test uptake, the patients tested, and patient management following testing were characterised.

RESULTS

A total of 17 027 patients had 19 840 FC tests recorded. The mean age of tested patients was 44.2 years. The first FC tests were documented in 2009. FC test use was still increasing in 2016. By 2016, 66.8% (n = 493/738) of practices had started FC testing. About one-fifth (20.7%, n = 1253/6051) of tests were carried out in patients aged ≥60 years. Only 7.8% (n = 473/6051) of the FC test records were preceded by symptoms eligible for FC testing. Only 3.1% (n = 1720/55 477) of patients with eligible symptoms have received FC testing since the national recommendations were published. There was only a small number of patients with symptoms, FC test, and a IBD diagnosis. In total, 71.3% (n = 1416/1987) of patients with a positive and 47.7% (n = 1337/2805) with a negative FC test were referred or further investigated.

CONCLUSION

Uptake of FC testing in clinical practice has been slow and inconsistent. The indication of non-compliance with national recommendations may suggest that these recommendations lack applicability to the general practice context.

Test accuracy of faecal calprotectin for inflammatory bowel disease in UK primary care: a retrospective cohort study of the IMRD-UK data

OBJECTIVE

To estimate the test accuracy of faecal calprotectin (FC) for inflammatory bowel disease (IBD) in the primary care setting using routine electronic health records.

DESIGN

Retrospective cohort test accuracy study.

SETTING

UK primary care.

PARTICIPANTS

5970 patients (≥18 years) without a previous IBD diagnosis and with a first FC test between 1 January 2006 and 31 December 2016. We excluded multiple tests and tests without numeric results in units of µg/g.

INTERVENTION

FC testing for the diagnosis of IBD. Disease status was confirmed by a recorded diagnostic code and/or a drug code of an IBD-specific medication at three time points after the FC test date.

MAIN OUTCOME MEASURES

Sensitivity, specificity, and positive and negative predictive values for the differential of IBD versus non-IBD and IBD versus irritable bowel syndrome (IBS) at the 50 and 100 µg/g thresholds.

RESULTS

5970 patients met the inclusion criteria and had at least 6 months of follow-up data after FC testing. 1897 had an IBS diagnosis, 208 had an IBD diagnosis, 31 had a colorectal cancer diagnosis, 80 had more than one diagnosis and 3754 had no subsequent diagnosis. Sensitivity, specificity, and positive and negative predictive values were 92.9% (88.6% to 95.6%), 61.5% (60.2% to 62.7%), 8.1% (7.1% to 9.2%) and 99.6% (99.3% to 99.7%), respectively, at the threshold of 50 µg/g. Raising the threshold to 100 µg/g missed less than 7% additional IBD cases. Longer follow-up had no effect on test accuracy. Overall, uncertainty was greater for specificity than sensitivity. General practitioners' (GPs') referral decisions did not follow the anticipated clinical pathways in national guidance.

CONCLUSIONS

GPs can be confident in excluding IBD on the basis of a negative FC test in a population with low pretest risk but should interpret a positive test with caution. The applicability of national guidance to general practice needs to be improved.

Systematic Review: Gastrointestinal Ultrasound Scoring Indices for Inflammatory Bowel Disease

BACKGROUND AND AIMS

Serial measurements of luminal disease activity may facilitate inflammatory bowel disease management. Gastrointestinal ultrasound is an easily performed, non-invasive alternative to other assessment modes. However, its widespread use is limited by concerns regarding validity, reliability, and responsiveness. We systematically identified ultrasound scoring indices used to evaluate inflammatory bowel disease activity and examine their operating characteristics.

METHODS

Electronic databases were searched from inception to June 14, 2019 using pre-defined terms. Studies that reported on gastrointestinal ultrasound index operating properties in an inflammatory bowel disease population were eligible for inclusion. Study characteristics, index components, and operating property data [ie, validity, reliability, responsiveness, sensitivity, specificity, accuracy, positive predictive value, and negative predictive value] were extracted. The QUADAS-2 tool was used to examine study-level risk of bias.

RESULTS

Of the 2610 studies identified, 26 studies reporting on 21 ultrasound indices were included. The most common index components included bowel wall thickness, colour Doppler imaging, and bowel wall stratification. The correlation between ultrasound indices and references standards ranged r = 0.62-0.95 and k = 0.40-0.96. Sensitivity, specificity, accuracy, positive predictive value, and negative predictive values ranged 39-100%, 63-100%, 73-100%, 57-100%, and 40-100%, respectively. Reliability and responsiveness data were limited. Most [92%, 24/26] studies received at least one unclear or high risk of bias rating.

CONCLUSIONS

Several gastrointestinal ultrasound indices for use in inflammatory bowel disease have been developed. Future research should focus on fully validating existing or novel gastrointestinal ultrasound scoring instruments for assessment of Crohn's disease and ulcerative colitis.

A Practical Guide for Faecal Calprotectin Measurement: Myths and Realities

BACKGROUND AND AIMS

Faecal calprotectin [FC] is a valid and non-invasive marker of mucosal inflammation. It is widely used both in clinical trials and in daily clinical practice for patients with inflammatory bowel diseases, but currently no accepted standardization for FC testing is available. Our primary aim here was to provide a clinician's guide containing all the practical information on FC measurement in order to avoid any confounding factors, to minimize intra- and inter-individual variability in dosage, and to ensure a better and adequate interpretation of the results.

METHODS

We conducted a detailed search of the scientific literature in the PubMed/MEDLINE, EMBASE and Cochrane databases up to January 2020 to find all relevant and available articles on pre-analytical and analytical phases of FC measurement.

RESULTS

FC testing is a multi-step procedure consisting of a pre-analytical phase aimed to collect and process the stool sample and a subsequent analytical phase of FC measurement. Several factors can influence test results determining false positives or false negatives. Importantly, this faecal marker is mostly used for patient follow-up and as a predictor of treatment response. For this reason, any altered data may affect the physicians' decisions, negatively impacting on patient management.

CONCLUSIONS

This review provides for the first time practical advice to minimize dosage variability, although further dedicated studies are needed to compare commercially available tests and identify the best tools for the most precise and accurate FC measurement.

Predictive values of stool-based tests for mucosal healing among Taiwanese patients with ulcerative colitis: a retrospective cohort analysis

Background/Purpose

Over the past two decades, ulcerative colitis (UC) has emerged in the Asia Pacific area, and its treatment goal has shifted from symptom relief to endoscopic remission. Endoscopy is the gold standard for the assessment of mucosal healing; however, it is an invasive method. Fecal calprotectin (FC) is a non-invasive stool-based inflammatory marker which has been used to monitor mucosal healing status, but it is expensive. By contrast, the immune fecal occult blood test (iFOBT) is a widely utilized stool-based screening tool for colorectal cancer. In this study, we compared the predictive values of iFOBT and FC for mucosal healing in Taiwanese patients with UC.

Methods

A total of 50 patients with UC identified via the electronic clinical database of Changhua Christian Hospital, Taiwan, were retrospectively enrolled from January 2018 to July 2019. Results of iFOBT, FC level, and blood tests as well as Mayo scores were reviewed and analyzed. Colonic mucosa was evaluated using the endoscopic Mayo subscore.

Results

The average age of the patients was 46 years, and 62% of the patients were men. Disease distribution was as follows: E1 (26%), E2 (40%), and E3 (34%). Complete mucosal healing (Mayo score = 0) was observed in 30% of patients. Endoscopic mucosal healing with a Mayo score of 0 or 1 was observed in 62% of the patients. Results of FC and iFOBT were compared among patients with and without mucosal healing. Predictive cutoff values were analyzed using receiver operating characteristics curves. iFOBT and FC had similar area under the curve for both complete mucosal healing (0.813 vs. 0.769, respectively, p = 0.5581) and endoscopic mucosal healing (0.906 vs. 0.812, respectively, p = 0.1207).

Conclusion

In daily clinical practice, FC and iFOBT do not differ in terms of predictive values for mucosal healing among Taiwanese patients with UC.

Are calprotectin and lactoferrin equivalent screening tests for inflammatory bowel disease?

BACKGROUND

Lactoferrin and calprotectin are frequently ordered stool tests used to screen patients for inflammatory bowel disease versus functional bowel disease. Current guidelines recommend using either one to screen for inflammation in the GI tract; however, little information is available on how these 2 assays compare and their use in different clinical specialties.

METHODS

We compared order patterns for lactoferrin and calprotectin using data from a large reference laboratory over a 10-y period (2009-2019). We also studied the concordance of lactoferrin and calprotectin in cases where both tests were ordered concurrently. Finally, we reviewed the records at a university hospital to determine which clinicians ordered each test and the indications associated with orders.

RESULTS

Orders for calprotectin are increasing relative to lactoferrin. The relative proportion of calprotectin orders have increased from 60% to nearly 90% over the past decade. Results for lactoferrin and calprotectin show concordance (90%). Calprotectin and lactoferrin are ordered by different clinical specialties for different indications. Calprotectin is most often ordered by gastroenterologists in the context of abdominal pain. Lactoferrin is most often ordered by primary care providers in the context of acute diarrhea.

CONCLUSION

Lactoferrin and calprotectin are not treated as equivalent tests by clinicians.

Chronic diarrhoea in children: A practical algorithm-based approach

Diarrhoea is a leading cause of morbidity and mortality world-wide. Most diarrhoeal episodes are acute and infectious in origin. Diarrhoea lasting for longer than 4 weeks with no discernible infectious aetiology warrants thorough evaluation. The aim of this review is to elucidate an approach to evaluation of diarrhoea based on its pathophysiologic mechanisms with focus on aetiology, investigation and management of chronic diarrhoea. It includes a brief description of normal fluid homeostasis in the gut and pathophysiology of diarrhoea. Further, diarrhoea is classified as 'watery', 'fatty' and 'bloody' based on stool characteristics. Relevant history, physical examination findings, first and second-line investigations which help in differentiating the different types of diarrhoea are listed and an algorithmic approach to individual types of diarrhoea has been devised. Principles of management and recent advances in diagnostics and therapeutics of diarrhoea are briefly discussed.

Diagnostic and clinical significance of antigen-specific pancreatic antibodies in inflammatory bowel diseases: A meta-analysis

BACKGROUND

Non-invasive criteria are needed for Crohn's disease (CD) diagnosis, with several biomarkers being tested. Results of individual diagnostic test accuracy studies assessing the diagnostic value of pancreatic autoantibodies-to-glycoprotein-2 (anti-GP2) tests for the diagnosis of CD appear promising.

AIM

To systematically review and meta-analyze evidence on the diagnostic accuracy of anti-GP2 tests in patients with suspected/confirmed CD.

METHODS

An electronic search was conducted on PubMed, Cochrane-CENTRAL and grey literature (CRD42019125947). The structured research question in PICPTR format was "Population" including patients with symptoms akin to CD, the "Index test" being anti-GP2 testing, the "Comparator" involved standard CD diagnosis, the "Purpose of test" being diagnostic, "Target disorder" was CD, and the "Reference standard" included standard clinical, radiological, endoscopical, and histological CD diagnostic criteria. Quality was assessed with the Quality Assessment of Diagnostic Accuracy Studies-2 tool and hierarchical models were employed to synthesize the data.

RESULTS

Out of 722 studies retrieved, 15 were meta-analyzed. Thirteen studies had industry-related conflicts-of-interest, and most included healthy donors as controls (spectrum bias). For the combination of IgA and/or IgG anti-GP2 test, the summary sensitivity was 20% (95% confidence interval: 10%-29%) at a median specificity of 97%. If the test was applied in 10000 suspected patients, 9669 would be true negatives and in 26, the diagnosis would be missed. In this hypothetical cohort, the anti-GP2 would fail to produce a diagnosis for 81.3% of the positive cases. Low summary points of sensitivity and high specificity were estimated for the IgG or IgA anti-GP2 test. Analogous results were observed when the analyses were restricted using specific cut-offs, or when ulcerative colitis patients were used as comparators.

CONCLUSION

Anti-GP2 tests demonstrate low sensitivity and high specificity. These results indicate that caution is required before relying on its diagnostic value. Additionally, the need for improving the methodology of diagnostic test accuracy studies is evident.