Validation of a care pathway for the use of faecal calprotectin in monitoring patients with Crohn's disease

Sample comparison of BÜHLMANN fCAL Turbo and OC-FCa faecal calprotectin methods

BACKGROUND

Faecal calprotectin is an inflammatory marker used to triage patients for further investigation with suspected inflammatory bowel disease (IBD). Our current method requires faecal samples be sent to the laboratory, where calprotectin is extracted before analysis. This is a time-consuming, potential bottleneck in the pathway. We have recently evaluated the OC-SENSOR PLEDIA fCAL method that uses the same sampling device as used in some bowel cancer screening and symptomatic colorectal cancer programmes that detect faecal haemoglobin. The below study is a comparison of the OC-FCa method with the BÜHLMANN fCAL Turbo which is used routinely within BSPS.

METHOD

150 homogenised and 110 non-homogenised faecal samples were loaded into OC-Sampling Bottle 3 and BÜHLMANN CALEX cap sampling devices. The samples were then analysed on their respective systems according to manufacturer's instructions.

RESULTS

The OC-FCa assay had a mean positive bias of 67.3% (homogenised) and 88.4% (non-homogenised). Homogenised samples showed substantial agreement between the methods for normal (<50 µg/g) and elevated (150+µg/g) risk categories (k = 0.794, k = 0.788, respectively) and moderate agreement for borderline (51-150 µg/g) (k = 0.25) according to the current Berkshire and Surrey Pathology Service (BSPS) guidelines. Non-homogenised samples had none to slight agreement for normal and borderline values (k = 0.02 for both) and moderate agreement for elevated (k = 0.596).

CONCLUSION

The OC-FCa method is a viable alternative for faecal calprotectin testing, but requires an adjustment to clinical cut-off values due to the lack of standardisation and strong positive bias. A clinical comparative study is required to assess the impact of patients collecting their own samples into the devices, as this may negate any potential degradation samples may exhibit during transit to the laboratory.

Comparison of faecal calprotectin using two collection and extraction strategies for the BÜHLMANN CALEX® Cap - possible implications for clinical cut-offs?

BACKGROUND

Faecal calprotectin has been identified as a useful biochemical marker in the differentiation of inflammatory bowel disease and irritable bowel syndrome. Typically, patients send faecal specimens in a pot for manual extraction by the laboratory. During the Severe Acute Respiratory Syndrome Coronavirus 2 (SARS CoV-2) pandemic, the routine laboratory service was temporarily suspended due to the potential increased risk to staff. In this study we investigated the possibility of patients collecting samples directly into the faecal extraction tubes.

METHOD

Patients submitted paired faecal samples for calprotectin analysis using a standard faecal container (current practice) and followed instructions for faecal collection using the BÜHLMANN CALEX® Cap device. Samples were returned to the laboratory immediately after collection. Laboratory staff manually extracted the calprotectin from the faecal samples using the CALEX® Cap prior to analysis of both extracts on the Cobas c702.

RESULTS

91 paired faecal samples were included in the study. Clinical correlation was found to be 70% with numerical correlation showing a positive bias for the patient-collected CALEX® Cap sample when compared to the laboratory-extracted faecal sample around the clinical decision points 100-250 μg calprotectin/g faeces.

CONCLUSION

The study shows that collection of a faecal sample using the CALEX® Cap works well and is a good alternative to using standard containers. The correlation gives rise to the possibility that faecal calprotectin is not stable when collected into standard collection containers. Prior to further roll-out of this process, questions surrounding the current cut-offs would need to be addressed.

Evaluation of a faecal calprotectin method using the OC-SENSOR PLEDIA

OBJECTIVES

The National Institute for Health and Care Excellence recommends faecal calprotectin (f-cal) to help differentiate inflammatory bowel diseases from irritable bowel syndrome. Faecal samples for calprotectin have historically been collected at home by patients into screw-top pots and sent to laboratories where calprotectin is extracted and analysed. Faecal haemoglobin (f-Hb) samples are collected at home into specific collection devices containing stabilising buffer. We evaluated the OC-FCa method for f-cal, developed by Eiken Chemical Co., Ltd. (Japan) that uses the same collection device and analyser as f-Hb.

METHODS

OC-FCa was assessed for limit of blank (LOB), limit of detection (LOD), limit of quantification (LOQ), within and between-run imprecision, linearity, prozone, recovery and carryover. A method comparison against the BÜHLMANN fCAL^® turbo (BÜHLMANN Laboratories AG, Switzerland) was performed using patient samples and EQA.

RESULTS

The LOB was 3 µg calprotectin/g faeces (µg/g), LOD 8 μg/g and LOQ 20 μg/g. Within and between-run imprecision was <5%; linearity was good (R² > 0.99); prozone was appropriately detected; recovery was 99.6%; no observed carryover. OC-FCa showed a strong positive bias compared with BÜHLMANN fCAL^® turbo (Z=-5.3587, p < 0.001). When categorised using our local pathway, which interprets calprotectin concentrations and need for further investigation, Cohen's Kappa demonstrates substantial agreement at <50 μg/g (κ=0.80) and >150 μg/g (κ=0.63) and fair agreement (κ=0.22) in the borderline category 50-150 μg/g.

CONCLUSIONS

The OC-FCa method performed well in the evaluation. With the lack of standardisation for f-cal a clinical study is required to evaluate the positive bias and establish suitable cut-off levels.

Is fecal calprotectin an accurate marker in the management of Crohn's disease?

Although lacking validated cutoff values, fecal calprotectin (FC), besides C-reactive protein, is considered the standard test for assessing disease activity in Crohn's disease (CD). The aim of the present review is to provide a general overview of the literature addressing the role of FC in the clinical and endoscopic assessment of disease activity in CD, seeking correlations with capsule endoscopy, response to therapy, prediction of relapse, and postoperative recurrence. A systematic search of the literature up to September 2019 was performed using Medline, Embase, and the Cochrane Library. Only papers written in English concerning FC in adult patients affected by CD were included. Pediatric studies, in vitro studies, animal studies, studies on blood/serum samples, and studies analyzing FC in ulcerative colitis or in both CD and ulcerative colitis were excluded. Out of 713 citations, 65 eligible studies were identified. FC showed high accuracy in the assessment of intestinal inflammation and response to therapy, in particular in colonic disease, thus proving a good surrogate marker for these aims. FC is useful in identifying patients at high risk for endoscopic relapse or postoperative recurrence, for optimizing or downstage therapy. Unfortunately, FC performs less well in small bowel CD. FC is an effective fecal marker in the management of CD patients, optimizing the use of endoscopic procedures. Owing to its diagnostic accuracy, FC may represent a cornerstone of the "treat-to-target" management strategy of CD patients.

Approaches to Integrating Biomarkers Into Clinical Trials and Care Pathways as Targets for the Treatment of Inflammatory Bowel Diseases

BACKGROUND & AIMS

There is no consensus on the best way to integrate biomarkers into inflammatory bowel disease (IBD) research and clinical practice. The International Organization for the Study of Inflammatory Bowel Disease aimed to outline biomarker definitions, categories, and operating properties required for their use in registration trials and clinical practice. Using fecal calprotectin as an example, we provide a framework for biomarker development and validation in patients with IBD.

METHODS

We reviewed international society guidelines, regulatory agency guidance documents, and standardized reporting guidelines for biomarkers, in combination with publications on fecal calprotectin levels in patients with IBD. We assessed the validity of fecal calprotectin to serve as a surrogate biomarker of IBD activity and outlined a framework for further validation and development of biomarkers.

RESULTS

No endpoints have been fully validated as surrogates of risk of disease complications; mucosal healing is the most valid endpoint used to determine risk of disease complications. Fecal level of calprotectin has not been validated as a biomarker for IBD activity because of lack of technical and clinical reliability, assessment of performance when used as a replacement for endoscopy, and assessment of responsiveness to changes in disease states. The level of fecal calprotectin can be used only as a prognostic factor for disease recurrence in patients in remission after medical or surgical treatment.

CONCLUSIONS

We reviewed guidelines, regulatory documents, and publications to identify properties required for the development of biomarkers of IBD activity and areas in need of clarification from regulatory agencies and societies. We propose a path forward for research of biomarkers for IBD.

Damage-associated molecular patterns in inflammatory bowel disease: From biomarkers to therapeutic targets

The chronic inflammatory process underlying inflammatory bowel disease (IBD), comprising Crohn’s disease and ulcerative colitis, derives from the interplay of several components in a genetically susceptible host. These components include environmental elements and gut microbiota a dysbiosis. For decades, immune abnormalities have been investigated as critically important in IBD pathogenesis, and attempts to develop effective therapies have predominantly targeted the immune system. Nevertheless, immune events represent only one of the constituents contributing to IBD pathogenesis within the context of the complex cellular and molecular network underlying chronic intestinal inflammation. These factors need to be appreciated within the milieu of non-immune components. Damage-associated molecular patterns (DAMPs), which are essentially endogenous stress proteins expressed or released as a result of cell or tissue damage, have been shown to act as direct pro-inflammatory mediators. Excessive or persistent signalling mediated by such molecules can underlie several chronic inflammatory disorders, including IBD. The release of endogenous DAMPs amplifies the inflammatory response driven by immune and non-immune cells and promotes epigenetic reprogramming in IBD. The effects determine pathologic changes, which may sustain chronic intestinal inflammation and also underlie specific disease phenotypes. In addition to highlighting the potential use of DAMPs such as calprotectin as biomarkers, research on DAMPs may reveal novel mechanistic associations in IBD pathogenesis and is expected to uncover putative therapeutic targets.