Positive and negative predictive values: use of inflammatory bowel disease serologic markers

Recent Trends in Non-Invasive Methods of Diagnosis and Evaluation of Inflammatory Bowel Disease: A Short Review

Inflammatory bowel diseases are a conglomerate of disorders causing inflammation of the gastrointestinal tract, which have gained a significant increase in prevalence in the 21st century. As they present a challenge in the terms of diagnosis as well as treatment, IBDs can present an overwhelming impact on the individual and can take a toll on healthcare costs. Thus, a quick and precise diagnosis is required in order to prevent the high number of complications that can arise from a late diagnosis as well as a misdiagnosis. Although endoscopy remains the primary method of evaluation for IBD, recent trends have highlighted various non-invasive methods of diagnosis as well as reevaluating previous ones. This review focused on the current non-invasive methods in the diagnosis of IBD, exploring their possible implementation in the near future, with the goal of achieving earlier, feasible, and cheap methods of diagnosis as well as prognosis in IBD.

The Correlation between New Serological Markers and Disease Phenotype and Activation in Inflammatory Bowel Disease

Background: The aim of the study is to assess the correlation between a new antibody panel that is developed against glycans on Crohn's disease (CD) and ulcerative colitis (UC) differentiative diagnosis and disease properties. Methods: In the study, 137 CD and 122 UC patients and 90 controls were included. Anti-saccharomyces cerevisiae IgG (ASCA), anti-laminaribioside IgG (ALCA), anti-chitobioside IgA (ACCA), and anti-mannobioside IgG (AMCA) were tested in serum. Results: While at least 1 of the other 3 serological markers was positive in 89% of ASCA-positive patients, at least 1 of the other 3 serological markers was positive in 77% of ASCA-negative patients. Positivity ratio for a single anticarbohydrate was ALCA 18 (22%), ACCA 5 (12%), and AMCA 16 (23%). A significant correlation was found between ASCA positivity (P<0.001) in operated patients and between ASCA, ALCA, and ACCA positivity (P<0.05) in patients with stricturing and fistulizing CD. According to the ROC analysis, ASCA was found to have the highest area under the curve (0.70-0.82) (correlation coefficient interval 95%). A significant correlation was found between ASCA, ALCA, and ACCA positivity and high serum antibody levels and disease activation (P<0.05). Conclusion: ASCA, ALCA, and ACCA were found to be correlated with the disease complication and activation in CD. ASCA and ALCA were determined as the best markers in the differentiation between CD and UC.

Circulating Fibroblast Activation Protein as Potential Biomarker in Patients With Inflammatory Bowel Disease

A major concern in the management of Inflammatory Bowel Disease (IBD) is the absence of accurate and specific biomarkers to drive diagnosis and monitor disease status timely and non-invasively. Fibroblast activation protein (FAP) represents a hallmark of IBD bowel strictures, being overexpressed in stenotic intestinal myofibroblasts. The present study aimed at evaluating the potential of circulating FAP (cFAP) as an accessible blood biomarker of IBD. Quantitative determination of cFAP was performed by enzyme-linked immunosorbent assay on plasma samples prospectively collected from patients with IBD and control subjects. A discrimination model was established on a training set of 50% patients and validated on independent samples. Results showed that cFAP concentration was reduced in patients with IBD when compared to controls (p < 0.0001). Age, sex, smoking, disease location and behavior, disease duration and therapy were not associated with cFAP. The sensitivity and specificity of cFAP in discriminating IBD from controls were 70 and 84%, respectively, based on the optimal cutoff (57.6 ng mL⁻¹, AUC = 0.78). Predictions on the test set had 57% sensitivity, 65% specificity, and 61% accuracy. There was no strong correlation between cFAP and routine inflammatory markers in the patients' population. A subgroup analysis was performed on patients with Crohn's disease undergoing surgery and revealed that cFAP correlates with endoscopic mucosal healing. In conclusion, cFAP deserves attention as a promising blood biomarker to triage patients with suspected IBD. Moreover, it might function as a biomarker of post-operative remission in patients with Crohn's disease.

The Biology and Disease Relevance of CD300a, an Inhibitory Receptor for Phosphatidylserine and Phosphatidylethanolamine

The CD300a inhibitory receptor belongs to the CD300 family of cell surface molecules that regulate a diverse array of immune cell processes. The inhibitory signal of CD300a depends on the phosphorylation of tyrosine residues embedded in ITIMs of the cytoplasmic tail. CD300a is broadly expressed on myeloid and lymphoid cells, and its expression is differentially regulated depending on the cell type. The finding that CD300a recognizes phosphatidylserine and phosphatidylethanolamine, two aminophospholipids exposed on the outer leaflet of dead and activated cells, has shed new light on its role in the modulation of immune functions and in its participation in the host response to several diseases states, such as infectious diseases, cancer, allergy, and chronic inflammatory diseases. This review summarizes the literature on CD300a expression, regulation, signaling pathways, and ligand interaction, as well as its role in fine tuning immune cell functions and its clinical relevance.

The CD300 molecules: an emerging family of regulators of the immune system

The CD300 family of molecules modulates a broad and diverse array of immune cell processes via their paired activating and inhibitory receptor functions. The description that CD300 molecules are able to recognize lipids, such as extracellular ceramide, phosphatidylserine, and phosphatidylethanolamine, that are exposed on the outer leaflet of the plasma membrane of dead and activated cells has opened a new field of research. Through their binding to lipids and other ligands, this family of receptors is poised to have a significant role in complex biological processes and in the host response to severe pathological conditions. Indeed, published data have demonstrated their participation in the pathogenesis of several disease states. Moreover, this family of receptors has great potential as targets for diagnosis and therapeutic purposes in infectious diseases, allergies, cancer, and other pathological situations. For instance, one member of the family, CD300a, has been studied as a possible biomarker. Here, a review is provided on the cellular distribution of the human and mouse families of receptors, the stimuli that regulate their expression, their ability to tune leukocyte function and immune responses, their signaling pathways, ligand recognition, and their clinical relevance.

The promise and pitfalls of serologic testing in inflammatory bowel disease

The role of IBD serologies is still evolving. However, as that evolution progresses, it will continue to provide important insights into the etiology of IBD and help define individualized treatment strategies for patients. The presence of multiple IBD antimicrobial antibodies and increased reactivity form a useful heuristic model to understand the evolution of CD. The role of ANCAs and autoantibodies in pathogenesis of UC is an area that requires further investigation. Although IBD serologies exhibit considerable diagnostic accuracy, it is unclear whether they will supplant simpler and more direct evaluations in making an initial diagnosis of UC or Crohn (Table 3). The utility of panels of IBD serologies to stratify and predict the course of CD has been an arena of fertile investigation. Developing individual treatment strategies based on the probability of developing complicated aggressive disease would be a significant advance in medical management of CD. However, if major clinical decisions are to be made based on these serologies, we will need more prospective critical studies from the time of diagnosis to define their clinical applicability and to demonstrate a true difference in outcomes.

Blood-based biomarkers can differentiate ulcerative colitis from Crohn's disease and noninflammatory diarrhea

BACKGROUND

Blood gene expression profiling has been used in several studies to identify patients with a number of conditions and diseases. A blood test with the ability to differentiate Crohn's disease (CD) from ulcerative colitis (UC) and noninflammatory diarrhea would be useful in the clinical management of these diseases.

METHODS

Affymetrix U133Plus 2.0 GeneChip oligonucleotide arrays were used to generate whole blood gene expression profiles for 21 patients with UC, 24 patients with CD, and 10 control patients with diarrhea, but without colonic pathology.

RESULTS

A supervised learning method (logistic regression) was used to identify specific panels of probe sets which were able to discriminate between UC and CD and from controls. The UC panel consisted of the four genes, CD300A, KPNA4, IL1R2, and ELAVL1; the CD panel comprised the four genes CAP1, BID, NIT2, and NPL. These panels clearly differentiated between CD and UC.

CONCLUSIONS

Gene expression profiles from blood can differentiate patients with CD from those with UC and from noninflammatory diarrheal disorders.

Serological markers for inflammatory bowel disease in AIDS patients with evidence of microbial translocation

BACKGROUND

Breakdown of the gut mucosal barrier during chronic HIV infection allows translocation of bacterial products such as lipopolysaccharides (LPS) from the gut into the circulation. Microbial translocation also occurs in inflammatory bowel disease (IBD). IBD serological markers are useful in the diagnosis of IBD and to differentiate between Crohn's disease (CD) and ulcerative colitis (UC). Here, we evaluate detection of IBD serological markers in HIV-infected patients with advanced disease and their relationship to HIV disease markers.

METHODS

IBD serological markers (ASCA, pANCA, anti-OmpC, and anti-CBir1) were measured by ELISA in plasma from AIDS patients (n = 26) with low CD4 counts (<300 cells/µl) and high plasma LPS levels, and results correlated with clinical data. For meta-analysis, relevant data were abstracted from 20 articles.

RESULTS

IBD serological markers were detected in approximately 65% of AIDS patients with evidence of microbial translocation. An antibody pattern consistent with IBD was detected in 46%; of these, 75% had a CD-like pattern. Meta-analysis of data from 20 published studies on IBD serological markers in CD, UC, and non-IBD control subjects indicated that IBD serological markers are detected more frequently in AIDS patients than in non-IBD disease controls and healthy controls, but less frequently than in CD patients. There was no association between IBD serological markers and HIV disease markers (plasma viral load and CD4 counts) in the study cohort.

CONCLUSIONS

IBD serological markers may provide a non-invasive approach to monitor HIV-related inflammatory gut disease. Further studies to investigate their clinical significance in HIV-infected individuals are warranted.

Inflammatory bowel disease in children: current trends

Once considered rare in the East, inflammatory bowel disease (IBD) is now recognized to be an emerging entity in that region. East or West, the clinical features of and treatment options for IBD are the same, but it is possible that the exact pathogeneses or the initiating events differ. In this review, existing knowledge of IBD and new discoveries in the epidemiology, genetics and treatment of IBD are discussed in detail. The diagnosis and management of IBD in children has changed dramatically over the last decade, mainly due to increased awareness, the availability of newer diagnostic modalities such as MRI and video capsule endoscopy, and newer, more powerful treatments such as biologics. It is hoped that the combination of innovative research and advances in drug discoveries will change the natural history of IBD and make a major difference in children who are suffering from this unfortunate lifelong chronic inflammatory disorder.

Novel diagnostic and prognostic modalities in inflammatory bowel disease

Inflammatory bowel disease remains a complex disease with variable clinical presentations and often nonspecific symptoms. Physicians must rely on diagnostic tools for clarification of disease diagnosis and for guiding management of patients with established disease. Advances in radiologic imaging modalities facilitate early and accurate detection of luminal disease and extraluminal complications. The introduction and dissemination of small bowel capsule endoscopy and double-balloon enteroscopy permit detailed visualization and sampling of the mucosa throughout the entire bowel. Serologic biomarkers are evolving as a valuable tool to clarify diagnosis and stratify patients by disease phenotypes and patterns of behavior. Neutrophil-derived fecal biomarkers are emerging as useful surrogate markers of intestinal inflammation with the potential for a variety of clinical applications, but their application to clinical management has not yet been clarified.

Novel diagnostic and prognostic modalities in inflammatory bowel disease

Inflammatory bowel disease remains a complex disease with variable clinical presentations and often nonspecific symptoms. Physicians must rely on diagnostic tools for clarification of disease diagnosis and for guiding management of patients with established disease. Advances in radiologic imaging modalities facilitate early and accurate detection of luminal disease and extraluminal complications. The introduction and dissemination of small bowel capsule endoscopy and double-balloon enteroscopy permit detailed visualization and sampling of the mucosa throughout the entire bowel. Serologic biomarkers are evolving as a valuable tool to clarify diagnosis and stratify patients by disease phenotypes and patterns of behavior. Neutrophil-derived fecal biomarkers are emerging as useful surrogate markers of intestinal inflammation with the potential for a variety of clinical applications, but their application to clinical management has not yet been clarified.

Crohn's disease clinical issues and treatment: what the radiologist needs to know and what the gastroenterologist wants to know

Crohn's disease is an idiopathic chronic intestinal illness that requires specialized medical care for prompt disease diagnosis and appropriate management. Clinicians must accurately interpret and integrate findings from multitude of sources in order to achieve diagnostic certainty. Ileocolonoscopy remains the most relied modality, allowing for a direct mucosal visualization and biopsies for histologic assessments. Serologic markers currently serve an adjunctive role, often utilized in attempts to further subtype patients with indeterminate colitis. Radiologic imaging, such as computed tomography enterography can evaluate the far reaches of the small intestine, while also providing information about penetrating complications and extraintestinal disease manifestations. Treatment options and strategies continue to evolve with new biologic agents and ongoing testing of aggressive "top-down" approaches. In addition, identification of increased colorectal cancer risks in individuals with Crohn's colitis has led to formal surveillance guidelines. The clinical diagnosis and management of Crohn's disease continues to be an area of rapid change and exciting developments.

Common Pitfalls in Management of Inflammatory Bowel Disease

Our understanding of inflammatory bowel disease (IBD), treatment options, complications and their management has expanded significantly over the past few decades. When caring for patients it is important to remember the complexities of pathogenesis and pharmacology. This review is to identify errors in diagnosis, treatment, complications and preventive care issues that arise while caring for patients with IBD and to provide recommendations and information that can be shared with patients and their health care providers. A review of the literature was undertaken using MEDLINE from 1981 to present. We included randomized controlled studies, case-control studies, and review articles. There are many associated conditions and complications recognized in patients with IBD and current treatment strategies do result in many side effects, some are serious and some are not widely recognized. With the advent of anti-TNF therapies and the newer 5-amino salicylate derivatives, options available have increased significantly. It is also important to remember that these patients are followed by more than one health care provider and it is important for all involved to communicate the plan of action.

Novel anti-glycan antibodies related to inflammatory bowel disease diagnosis and phenotype

OBJECTIVES

We sought to evaluate whether two novel immunoglobulin A (IgA) cell wall polysaccharide antibodies, anti-laminarin (anti-L) and anti-chitin (anti-C), aid in the diagnosis and phenotype differentiation of Crohn's disease (CD) and ulcerative colitis (UC).

METHODS

A cohort of 818 individuals with inflammatory bowel disease (IBD; 517 CD and 301 UC) from two IBD tertiary referral centers, with median ages of 33 and 39 years, respectively, and disease duration of 8.9 years, were phenotyped using the Montreal classification, and analyzed for seven anti-glycan antibodies (gASCA (anti-Saccharomyces cerevisiae) IgG, gASCA IgA, anti-chitobioside (GlcNAc(beta1,4)GlcNAc(beta)), anti-laminaribioside (Glc(beta1,3)Glb(beta)), anti-mannobioside (Man(alpha1,3)Man(alpha)), anti-L, and anti-C) and perinuclear atypical neutrophil cytoplasmic antibodies (pANCA).

RESULTS

In the CD patient population, 73% were positive for >/=1 anti-glycan antibody. All glycan markers were specific for CD (85.4-97.7%) and more prevalent in CD vs. UC (P<0.0015). gASCA IgG and IgA best differentiated CD from UC followed by anti-L (area under the curve 0.818, 0.815, and 0.702, respectively). The addition of anti-L and anti-C to gASCA IgG and pANCA improved discrimination between CD and UC (P<0.001). Adding anti-L to gASCA and pANCA differentiated colonic CD and UC (P=0.02). An increasing number of positive antibodies was associated with early CD onset, penetrating phenotype, perianal disease, and the need for surgery (P<0.001). Anti-L was associated with ileocolonic CD (odds ratio (OR) 2.28, 95% confidence interval (CI) 1.40-3.69; P=0.001), and anti-C with penetrating (OR 2.75, 95% CI 1.50-5.04; P=0.001) and perianal disease (OR 1.95, 95% CI 1.06-3.59; P=0.03).

CONCLUSIONS

Anti-L and anti-C improve differentiation between CD and UC. Anti-L may also differentiate between isolated colonic CD and UC. Both anti-L and anti-C are independently associated with a more aggressive CD phenotype.

Antiglycan antibodies as serological markers in the differential diagnosis of inflammatory bowel disease

BACKGROUND

The objective of the study was to evaluate the diagnostic accuracy of recently developed antiglycan serological tests in clinical practice for the diagnosis of Crohn's disease.

METHODS

This study was a cohort analysis of both clinical and biochemical parameters of patients with diagnosed inflammatory bowel disease compared with those in a control population. Antiglycan antibodies were determined using commercially available enzyme immunoassays. The setting was the outpatient unit of the gastroenterology department of a large, tertiary-care referral academic hospital. Participants were 214 consecutive patients, enrolled over a 5-month period, including 116 with Crohn's disease and 53 with ulcerative colitis, as well as 45 with other gastrointestinal diseases and 51 healthy controls.

RESULTS

Anti-Saccharomyces cerevisiae antibodies showed the best performance (54% sensitivity and 88%-95% specificity for Crohn's disease). Among patients with negative anti-Saccharomyces antibodies, 19 (34%) had high titers of at least another tested antiglycan antibody. Anti-Saccharomyces and anti-laminaribioside antibodies were associated with disease involving the small bowel and with penetrating or stricturing phenotype. Anti-laminaribioside was significantly higher in patients with a familial history of inflammatory bowel disease.

CONCLUSIONS

The new proposed serological markers are significantly associated with Crohn's disease, with low sensitivity but good specificity. About one third of anti-Saccharomyces-negative patients may be positive for at least 1 of those markers. Antiglycan antibodies appear to be associated with characteristic localization and phenotype of the disease.

Cost-effectiveness analysis of strategies for diagnosing celiac disease

OBJECTIVE

To compare strategies for diagnosing celiac disease (CD).

METHODS

A decision analytic model was used to compare five strategies on diagnostic performance and costs.

RESULTS

First, tTG screening alone is the least costly strategy ($22/individual). While the NPV is high (99.8%), the PPV is low (63.4%). Second, if tTG-positive patients undergo esophagogastroduodenoscopy (EGD) to confirm CD, the PPV increases to 100% ($2,237/false-positive diagnosis avoided). Third, if EGDs are restricted to only those who are both tTG and HLA DQ2/8 positive, costs are slightly reduced ($59 vs. $63/individual), while PPV and NPV remain unchanged. Fourth, screening tTG-negative patients for IgA deficiency increases the NPV to 99.9% ($32,605/false-negative diagnosis avoided). Sensitivity analyses revealed that as the prevalence of CD increases, the cost of avoiding a false-positive diagnosis by adding EGD to the tTG alone strategy increases considerably.

CONCLUSIONS

When the pre-test probability of CD is low, patients with positive tTG serology should undergo EGD with biopsy-either directly or after positive screening for HLA DQ2/8-to confirm CD. As the pre-test probability of CD increases, the added cost of EGD should be weighed against the consequences of a false-positive diagnosis. Routinely screening for IgA deficiency in order to avoid a false-negative diagnosis is quite costly.

Serologic markers in inflammatory bowel disease: tools for better diagnosis and disease stratification

In the last decade, new serologic markers have been identified, and attempts to delineate their potential roles in inflammatory bowel disease diagnosis, determination of prognosis and identification of apparently healthy subjects at risk have significantly increased our knowledge. In this review, the major serologic markers will be described, focusing on their common features as a group. It is predicted that within the next 5 years, panels of antibodies will prove to have a significant impact on disease diagnosis and stratification, as well as on the identification of populations at risk and the prediction of response to treatment. Thus, it is expected that they will become useful clinical tools that will enable an improved, 'tailored' approach to inflammatory bowel disease patients.

Current and future diagnostic approaches: from serologies to imaging

Advances in serologic markers and imaging modalities continue to revolutionize diagnostic approaches to inflammatory bowel disease (IBD). Autoimmune and antimicrobial antibodies demonstrate diagnostic value in those patients with a moderate pretest probability of disease. Emerging data also support the use of antimicrobial antibody levels as a predictive tool for small bowel complications and the need for future surgery. In addition to being a prognostic marker in patients with acute severe colitis, serum C-reactive protein has been shown to correlate with clinical, endoscopic, and radiologic measures of disease activity. Capsule endoscopy and double-balloon endoscopy allow for visualization of the entire small bowel, and double-balloon endoscopy also has the capability to treat lesions. CT enterography is beginning to replace small bowel follow-through because of its high sensitivity and specificity for disease of the small intestine. Both CT and magnetic resonance enterography detect luminal and extraluminal abnormalities, with MRI serving as a safe imaging option in cases of pregnancy and renal insufficiency. These newer modalities add to the armamentarium clinicians can use for evaluation of IBD.

Antibodies to Escherichia coli outer membrane porin C in the absence of anti-Saccharomyces cerevisiae antibodies and anti-neutrophil cytoplasmic antibodies are an unreliable marker of Crohn disease and ulcerative colitis

OBJECTIVES

Antibodies to Escherichia coli outer membrane porin C (anti-OmpC), Saccharomyces cerevisiae, and neutrophil-specific nuclear antigens are associated with inflammatory bowel disease (IBD) in children and young adults. We hypothesized that anti-OmpC, in the absence of anti-S cerevisiae antibodies (ASCA) and antineutrophil cytoplasmic antibodies (ANCA), is an assay that overestimates the presence of Crohn disease (CD) and ulcerative colitis (UC).

PATIENTS AND METHODS

A retrospective review of patients evaluated at our institution between January 2002 and June 2006 revealed that 170 had serodiagnostic immunological assays performed as part of an evaluation for possible IBD. The assays were screened for a pattern in which anti-OmpC was present in the absence of ASCA and ANCA.

RESULTS

Seven patients between 3 and 20 years of age were discovered to be positive for anti-OmpC but negative for ASCA and ANCA. These patients were determined to have significant medical conditions without combined radiographic, endoscopic, or histological evidence of IBD. Despite the reported 85% positive predictive value of anti-OmpC for IBD, none of the 7 patients with isolated anti-OmpC had a diagnosis of CD or UC.

CONCLUSIONS

Anti-OmpC, in the absence of ASCA and ANCA, is a serological pattern noted in a subset of medically complex cases in children and young adults without CD or UC.

Evolving diagnostic strategies for inflammatory bowel disease

Advances in serologic markers, endoscopy, and radiology have led to rapid expansion of diagnosis and disease activity assessment of inflammatory bowel disease (IBD). Serologic markers may have diagnostic value in patients with an intermediate pretest probability of IBD, but these serology tests lack complete sensitivity, and a negative serology result does not exclude the possibility of IBD. Several recent studies have confirmed the utility of serologies in predicting intestinal complications and need for surgery in Crohn's disease. Serum C-reactive protein concentrations correlate with clinical, endoscopic, and radiologic measures of disease activity and appear to have prognostic value in acute severe colitis. Capsule and double balloon endoscopy allow visual inspection of previously inaccessible areas of the small intestine and are useful for patients with suspected small bowel involvement but negative results on conventional testing. CT enterography, which entails oral ingestion of a large volume of a neutral or negative contrast agent and scanning that highlights differences in contrast between the lumen and the bowel wall, appears to be more sensitive than small bowel follow-through for detecting small bowel Crohn's disease and provides extraluminal information. Magnetic resonance enterography uses principles similar to those for CT enterography, and early results are encouraging.