SeHCAT [tauroselcholic (selenium-75) acid] for the investigation of bile acid malabsorption and measurement of bile acid pool loss: a systematic review and cost-effectiveness analysis

The analysis of gut microbiota in patients with bile acid diarrhoea treated with colesevelam

Introduction

Bile acid diarrhoea (BAD) is a common disorder that results from an increased loss of primary bile acids and can result in a change in microbiome. The aims of this study were to characterise the microbiome in different cohorts of patients with BAD and to determine if treatment with a bile acid sequestrant, colesevelam, can alter the microbiome and improve microbial diversity.

Materials and methods

Patients with symptoms of diarrhoea underwent 75-selenium homocholic acid (75SeHCAT) testing and were categorised into four cohorts: idiopathic BAD, post-cholecystectomy BAD, post-operative Crohn’s disease BAD and 75SeHCAT negative control group. Patients with a positive 75SeHCAT (<15%) were given a trial of treatment with colesevelam. Stool samples were collected pre-treatment, 4-weeks, 8-weeks and 6–12 months post-treatment. Faecal 16S ribosomal RNA gene analysis was undertaken.

Results

A total of 257 samples were analysed from 134 patients. α-diversity was significantly reduced in patients with BAD and more specifically, in the idiopathic BAD cohort and in patients with severe disease (SeHCAT <5%); p < 0.05. Colesevelam did not alter bacterial α/β-diversity but patients who clinically responded to treatment had a significantly greater abundance of Fusobacteria and Ruminococcus, both of which aid in the conversion of primary to secondary bile acids.

Conclusion

This is the first study to examine treatment effects on the microbiome in BAD, which demonstrated a possible association with colesevelam on the microbiome through bile acid modulation in clinical responders. Larger studies are now needed to establish a causal relationship with colesevelam and the inter-crosstalk between bile acids and the microbiome.

Comparing the accuracy of the new-generation intraocular lens power calculation formulae in axial myopic eyes: a meta-analysis

PURPOSE

To compare the accuracy of the new-generation intraocular lens power calculation formulae in axial myopic eyes.

METHODS

Four databases, PubMed, Web of Science, EMBASE and Cochrane library, were searched to select relevant studies published between Apr 11, 2011, and Apr 11, 2021. Axial myopic eyes were defined as an axial length more than 24.5 mm. There are 13 formulae to participate in the final comparison (SRK/T, Hoffer Q, Holladay I, Holladay II, Haigis for traditional formulae, Barrett Universal II, Olsen, T2, VRF, EVO, Kane, Hill-RBF, LSF for the new-generation formulae). The primary outcomes were the percentage of eyes with a refractive prediction error in ± 0.5D and ± 1.0D.

RESULTS

A total of 2273 eyes in 15 studies were enrolled in the final meta-analysis. Overall, the new-generation formulae showed a relatively more accurate outcome in comparison with traditional formulae. The percentage of eyes with a predictive refraction error in ± 0.5D (± 1.0D) of Kane, EVO and LSF was higher than 80% (95%), which was only significantly different from Hoffer Q (all P < 0.05). Moreover, another two new-generation formulae, Barrett Universal II and Olsen, had higher percentages than SRK/T, Hoffer Q, Holladay I and Haigis for eyes with predictive refraction error in ± 0.5D and ± 1.0D (all P < 0.05). In ± 0.5D group, Hill-RBF was better than SRK/T (P = 0.02), and Holladay I was better than EVO (P = 0.03) and LSF (P = 0.009), and Hoffer Q had a lower percentage than EVO, Kane, Hill-RBF and LSF (P = 0.007, 0.004, 0.002, 0.03, respectively). Barrett Universal II was better than T2 (P = 0.02), and Hill-RBF was better than SRK/T (P = 0.009). No significant difference was found in other pairwise comparison.

CONCLUSION

The new-generation formula is more accurate in intraocular lens power calculation for axial myopic eyes in comparison with the third- or fourth-generation formula.

Chologene Diarrhö, Stiefkind der chronischen Diarrhö – Prävalenz, Diagnostik und Therapie

Die chologene Diarrhö ist eine der häufigsten nicht diagnostizierten Ursachen der chronischen Diarrhö, der zahlreiche verschiedene Pathophysiologien zugrunde liegen können. Auch nach Ausschlussdiagnostik der häufigeren Ursachen verbleiben bis zu 5% der Bevölkerung von einer ungeklärten chronischen Diarrhö betroffen. In diesem Kollektiv findet sich in bis zu 50% als Ursache eine chologene Diarrhö.

SeHCAT (tauroselcholic [75selenium] acid) for the investigation of bile acid diarrhoea in adults: a systematic review and cost-effectiveness analysis

Background

Tauroselcholic [75selenium] acid (SeHCAT™) (GE Healthcare, Chicago, IL, USA) is a radiopharmaceutical that may be useful in diagnosing bile acid diarrhoea.

Objectives

To assess the clinical effectiveness and cost-effectiveness of SeHCAT for the investigation of adults with chronic unexplained diarrhoea, diarrhoea-predominant irritable bowel syndrome or functional diarrhoea (suspected primary bile acid diarrhoea), and adults with chronic diarrhoea and Crohn’s disease who have not undergone ileal resection (suspected secondary bile acid diarrhoea).

Methods

Sixteen databases were searched to November 2020. The review process included measures to minimise error and bias. Results were summarised by primary or secondary bile acid diarrhoea and study quality was considered. The cost-effectiveness analysis combined a short-term (6-month) decision-analytic model (diagnosis and initial treatment response) and a lifetime Markov model comprising three health states (diarrhoea, no diarrhoea and death), with transitions determined by probabilities of response to treatment. Analyses were conducted from an NHS and Personal Social Services perspective.

Results

Twenty-four studies were included in this review. Of these, 21 were observational studies, reporting some outcome data for patients treated with bile acid sequestrants, and in which only patients with a positive SeHCAT test were offered bile acid sequestrants. The median rate of response to bile acid sequestrants, among patients with a 7-day SeHCAT retention value of ≤ 15%, was 68% (range 38–86%) (eight studies). The estimated sensitivity of SeHCAT (≤ 15% threshold) to predict positive response to colestyramine was 100% (95% confidence interval 54.1% to 100%) and the specificity estimate was 91.2% (95% confidence interval 76.3% to 98.1%) (one study). The median proportion of treated patients who were intolerant/discontinued bile acid sequestrants was 15% (range 4–27%) (eight studies). There was insufficient information to determine whether or not intolerance varied between colestyramine, colestipol and colesevelam. For both populations, the SeHCAT 15% (i.e. a SeHCAT retention value of ≤ 15%) strategy dominated other strategies or resulted in incremental cost-effectiveness ratios of < £20,000–30,000 per quality-adjusted life-year gained. For the suspected primary bile acid diarrhoea population, SeHCAT 15% was the strategy most likely to be cost-effective: 67% and 73% probability at threshold incremental cost-effectiveness ratios of £20,000 and £30,000 per quality-adjusted life-year gained, respectively. For the Crohn’s disease population, these probabilities were 89% and 92% at £20,000 and £30,000 per quality-adjusted life-year gained, respectively. Cost-effectiveness was mostly led by treatment response. SeHCAT 15% was the strategy with the highest response rate in the majority of scenarios explored.

Limitations and conclusions

There is a lack of evidence linking the use of SeHCAT testing to patient-relevant outcomes. The optimal SeHCAT threshold, to define bile acid diarrhoea and select patients for treatment with bile acid sequestrants, is uncertain. It is unclear whether or not patients with ‘borderline’ or ‘equivocal’ 7-day SeHCAT retention values (e.g. between 10% and 15%) and patients with values of > 15% could benefit from treatment with bile acid sequestrants. Although the results of the economic evaluation conducted for both populations indicated that the SeHCAT 15% strategy dominated the other two strategies or resulted in incremental cost-effectiveness ratios that were lower than the common thresholds of £20,000 or £30,000 per quality-adjusted life-year gained, the paucity and poor quality of evidence mean that uncertainty is high.

Future work

The optimum study design would be a multiarm randomised controlled trial, in which participants meeting the inclusion criteria are randomised to receive colestyramine, colestipol, colesevelam or placebo, and all participants receive SeHCAT testing.

Study registration

This study is registered as PROSPERO CRD42020223877.

Funding

This project was funded by the National Institute for Health and Care Research (IHR) Evidence Synthesis programme and will be published in full in Health Technology Assessment; Vol. 26, No. 45. See the NIHR Journals Library website for further project information.

Bile Acid-Related Regulation of Mucosal Inflammation and Intestinal Motility: From Pathogenesis to Therapeutic Application in IBD and Microscopic Colitis

Inflammatory bowel diseases (IBD) and microscopic colitis are chronic immune-mediated inflammatory disorders that affect the gastroenterological tract and arise from a complex interaction between the host’s genetic risk factors, environmental factors, and gut microbiota dysbiosis. The precise mechanistic pathways interlinking the intestinal mucosa homeostasis, the immunological tolerance, and the gut microbiota are still crucial topics for research. We decided to deeply analyze the role of bile acids in these complex interactions and their metabolism in the modulation of gut microbiota, and thus intestinal mucosa inflammation. Recent metabolomics studies revealed a significant defect in bile acid metabolism in IBD patients, with an increase in primary bile acids and a reduction in secondary bile acids. In this review, we explore the evidence linking bile acid metabolites with the immunological pathways involved in IBD pathogenesis, including apoptosis and inflammasome activation. Furthermore, we summarize the principal etiopathogenetic mechanisms of different types of bile acid-induced diarrhea (BAD) and its main novel diagnostic approaches. Finally, we discuss the role of bile acid in current and possible future state-of-the-art therapeutic strategies for both IBD and BAD.

Evaluation of the Cost-Effectiveness of Iron Formulations for the Treatment of Iron Deficiency Anaemia in Patients with Inflammatory Bowel Disease in the UK

Introduction

In patients with inflammatory bowel disease (IBD), iron deficiency anaemia (IDA) can impair quality of life and increase healthcare costs. Treatment options for IDA-associated IBD include oral iron and intravenous iron formulations (such as ferric carboxymaltose [FCM], ferric derisomaltose [FD, previously known as iron isomaltoside 1000], and iron sucrose [IS]). The present analysis compared the cost-effectiveness of FCM versus FD, IS, and oral iron sulfate in terms of additional cost per additional responder in the UK setting.

Methods

Cost-effectiveness was calculated for FCM versus FD, IS, and oral iron individually in terms of the additional cost per additional responder, defined as haemoglobin normalisation or an increase of ≥2 g/dL in haemoglobin levels, in a model developed in Microsoft Excel. Relative efficacy inputs were taken from a previously published network meta-analysis, since there is currently no single head-to-head trial evidence comparing all therapy options. Costs were calculated in 2020 pounds sterling (GBP) capturing the costs of iron preparations, healthcare professional time, and consumables.

Results

The analysis suggested that FCM may be the most effective intervention, with 81% of patients achieving a response. Response rates with FD, IS, and oral iron were 74%, 75%, and 69%, respectively. Total costs with FCM, FD, IS, and oral iron were GBP 296, GBP 312, GBP 503, and GBP 56, respectively. FCM was found to be more effective and less costly than both FD and IS, and therefore was considered dominant. Compared with oral iron, FCM was associated with an incremental cost-effectiveness ratio of GBP 2045 per additional responder.

Conclusions

FCM is likely to be the least costly and most effective IV iron therapy in the UK setting. Compared with oral iron, healthcare payers must decide whether the superior treatment efficacy of FCM is worth the additional cost.

Manipulating the Microbiome: An Alternative Treatment for Bile Acid Diarrhoea

Bile acid diarrhoea (BAD) is a widespread gastrointestinal disease that is often misdiagnosed as irritable bowel syndrome and is estimated to affect 1% of the United Kingdom (UK) population alone. BAD is associated with excessive bile acid synthesis secondary to a gastrointestinal or idiopathic disorder (also known as primary BAD). Current licensed treatment in the UK has undesirable effects and has been the same since BAD was first discovered in the 1960s. Bacteria are essential in transforming primary bile acids into secondary bile acids. The profile of an individual’s bile acid pool is central in bile acid homeostasis as bile acids regulate their own synthesis. Therefore, microbiome dysbiosis incurred through changes in diet, stress levels and the introduction of antibiotics may contribute to or be the cause of primary BAD. This literature review focuses on primary BAD, providing an overview of bile acid metabolism, the role of the human gut microbiome in BAD and the potential options for therapeutic intervention in primary BAD through manipulation of the microbiome.

Serum 7-alfa-hydroxy-4-cholesten-3-one and fibroblast growth factor-19 as biomarkers diagnosing bile acid malabsorption in microscopic colitis and inflammatory bowel disease

BACKGROUND

Bile acid malabsorption is common in microscopic colitis, irritable bowel syndrome with diarrhea, and inflammatory bowel disease. We investigated the diagnostic accuracy of 7-alfa-hydroxy-4-cholesten-3-one and compared it with fibroblast growth factor-19 as biomarkers for bile acid malabsorption.

METHODS

We enrolled consecutively 109 chronic diarrhea patients with standard laboratory tests, fecal calprotectin, and endoscopy separated into six groups: n = 30 with active inflammatory bowel disease, n = 21 with inflammatory bowel disease in remission reporting >3 bowel movements per day, n = 21 with inflammatory bowel disease after surgery, n = 23 with irritable bowel syndrome with diarrhea, n = 14 with microscopic colitis and 11 healthy subjects (controls). We defined bile acid malabsorption as >3 bowel movements and lower fibroblast growth factor-19 (<60 pg/ml).

RESULTS

Median levels of 7-alfa-hydroxy-4-cholesten-3-one in inflammatory bowel disease active were 53.1 ng/ml, inflammatory bowel disease remission were 52.2 ng/ml, inflammatory bowel disease after surgery were 85.7 ng/ml, irritable bowel syndrome with diarrhea were 7.5 ng/ml, microscopic colitis were 69.3 ng/ml, and healthy controls were 3.7 ng/ml. We estimate a 7-alfa-hydroxy-4-cholesten-3-one cutoff of 48.9 ng/ml with 82.6% sensitivity and 84.3% specificity for detecting bile acid malabsorption. Both 7-alfa-hydroxy-4-cholesten-3-one >48.9 ng/ml and fibroblast growth factor-19 (<60 pg/ml) were found in 52% of the patients, compared with those 8% of patients below this 7-alfa-hydroxy-4-cholesten-3-one cutoff (P < 0.001). Serum 7-alfa-hydroxy-4-cholesten-3-one correlated with the number of bowel movements/day (r = -0.709; P < 0.001) and correlated inversely with fibroblast growth factor-19 (r = -0.741; P < 0.001).

CONCLUSIONS

Serum 7-alfa-hydroxy-4-cholesten-3-one above 48.9 ng/ml and fibroblast growth factor-19 below 60 pg/ml identify patients with diarrhea likely attributable to bile acid malabsorption with high diagnostic accuracy and they can be used as screening biomarkers for bile acid malabsorption in microscopic colitis and inflammatory bowel disease.

[Bile acid diarrhea, stepchild of chronic diarrhea - prevalence, diagnosis and treatment. Update 2021]

Bile acid diarrhea is one of the most frequently undiagnosed causes of chronic diarrhea. A variety of different pathophysiologic causes can underlie chronic diarrhea. Even after exclusion of the more frequent causes, up to 5 % of the population remains affected by unexplained chronic diarrhea. In up to 50 % within this cohort, bile acid diarrhea is the underlying cause.The various pathophysiologies leading to bile acid diarrhea are well characterized. In this way, bile acid diarrhea can be divided into primary, secondary and tertiary subtypes. Common to all causes is the increased amount of bile acids in the colon and in the faeces and the resulting secretory-osmotic diarrhea, in more severe forms in combination with steatorrhea. The diagnosis of bile acid diarrhea follows a clear algorithm which, in addition to the search for the cause and possibly a therapeutic trial, recognizes the 75SeHCAT test as the reference method for the detection of an increased loss of bile acids. In view of the chronic nature of the symptoms and the need for permanent, lifelong therapy, the use of a one-time, reliable diagnostic test is justified, though the test is currently only available at a few centers. In addition to the treatment of identifiable underlying diseases, the current treatment includes the use of drugs that bind bile acids, with additional nutritional recommendations and vitamin substitutions.The present review article summarizes the pathophysiology and importance of bile acid diarrhea and discusses the current approach towards diagnosis and treatment.

Expanding PET-applications in life sciences with positron-emitters beyond fluorine-18

Positron-emission-tomography (PET) has become an indispensable diagnostic tool in modern nuclear medicine. Its outstanding molecular imaging features allow repetitive studies on one individual and with high sensitivity, though no interference. Rather few positron-emitters with near favourable physical properties, i.e. carbon-11 and fluorine-18, furnished most studies in the beginning, preferably if covalently bound as isotopic label of small molecules. With the advancement of PET-devices the scope of in vivo research in life sciences and especially that of medical applications expanded, and other than "standard" PET-nuclides received increasing significance, like the radiometals copper-64 and gallium-68. Especially during the last decades, positron-emitters of other chemical elements have gotten into the focus of interest, concomitant with the technical advancements in imaging and radionuclide production. With known nuclear imaging properties and main production methods of emerging positron-emitters their usefulness for medical application is promising and even proven for several ones already. Unfortunate decay properties could be corrected for, and β+-emitters, especially with a longer half-life, provided new possibilities for application where slower processes are of importance. Further on, (bio)chemical features of positron-emitters of other elements, among there many metals, not only expanded the field of classical clinical investigations, but also opened up new fields of application. Appropriately labelled peptides, proteins and nanoparticles lend itself as newer probes for PET-imaging, e.g. in theragnostic or PET/MR hybrid imaging. Furthermore, the potential of non-destructive in-vivo imaging with positron-emission-tomography directs the view on further areas of life sciences. Thus, exploiting the excellent methodology for basic research on molecular biochemical functions and processes is increasingly encouraged as well in areas outside of health, such as plant and environmental sciences.

Iron Formulations for the Treatment of Iron Deficiency Anemia in Patients with Inflammatory Bowel Disease: A Cost-Effectiveness Analysis in Switzerland

INTRODUCTION

Iron deficiency anemia (IDA) is a common complication of inflammatory bowel disease (IBD) and can result in reduced quality of life and increased healthcare costs. IDA is treated with iron supplementation, either with oral iron therapy (OI) or intravenous iron formulations, including ferric carboxymaltose (FCM), iron isomaltoside 1000 (IIM), and iron sucrose (IS). This analysis compared the cost-effectiveness of FCM versus IIM, IS, and OI in terms of additional cost per additional responder in Switzerland.

METHODS

A health economic model was developed to assess the additional cost per additional responder, defined as normalization or an increase of at least 2 g/dL in hemoglobin levels, for FCM versus IIM, IS, and OI. To date, no single head-to-head trial comparing all therapies is available, and therefore relative efficacy data were taken from a published network meta-analysis. Costs of treatment were calculated in 2020 Swiss francs (CHF) using a microcosting approach, and included the costs of iron, healthcare professional time, and consumables. Costs are also presented in euros (EUR) based on an exchange rate of CHF 1 = EUR 0.94.

RESULTS

Response rates with FCM, IIM, IS, and OI were 81%, 74%, 75%, and 69%, respectively, with FCM projected to be the most effective treatment. FCM was associated with cost savings of CHF 24 (EUR 23) versus IIM and of CHF 147 (EUR 138) versus IS, and increased costs by CHF 345 (EUR 324) versus OI. Therefore FCM was considered dominant versus both IIM and IS, improving clinical outcomes with cost savings. FCM was associated with an incremental cost-effectiveness ratio of CHF 2970 (EUR 2792) per additional responder versus OI.

CONCLUSIONS

FCM was projected to be the most cost-effective intravenous iron therapy in Switzerland, increasing the number of responders and leading to cost savings for healthcare payers.

Bile acid diarrhoea: pathophysiology, diagnosis and management

The actual incidence of bile acid diarrhoea (BAD) is unknown, however, there is increasing evidence that it is misdiagnosed in up to 30% with diarrhoea-predominant patients with irritable bowel syndrome. Besides this, it may also occur following cholecystectomy, infectious diarrhoea and pelvic chemoradiotherapy. BAD may result from either hepatic overproduction of bile acids or their malabsorption in the terminal ileum. It can result in symptoms such as bowel frequency, urgency, nocturnal defecation, excessive flatulence, abdominal pain and incontinence of stool. Bile acid synthesis is regulated by negative feedback loops related to the enterohepatic circulation, which are dependent on the farnesoid X receptor and fibroblast growth factor 19. Interruption of these feedback loops is thought to cause bile acid overproduction leading to BAD. This process may occur idiopathically or following a specific trigger such as cholecystectomy. There may also be an interplay with the gut microbiota, which has been reported to be significantly different in patients with severe BAD. Patients with suspected BAD are investigated in various ways including radionucleotide imaging such as SeHCAT scans (though this is not available worldwide) and blood tests. However, other methods such as bile acid measurement in stool (either spot test or 48 hours samples) and urine tests have been explored. Importantly, delay in diagnosis and treatment of BAD greatly affects patient's quality of life and may double the overall cost of diagnosis.

Differences in Fecal Microbiomes and Metabolomes of People With vs Without Irritable Bowel Syndrome and Bile Acid Malabsorption

BACKGROUND & AIMS

Irritable bowel syndrome (IBS) is a heterogeneous disorder, but diagnoses and determination of subtypes are made based on symptoms. We profiled the fecal microbiomes of patients with and without IBS to identify biomarkers of this disorder.

METHODS

We collected fecal and urine samples from 80 patients with IBS (Rome IV criteria; 16-70 years old) and 65 matched individuals without IBS (control individuals), along with anthropometric, medical, and dietary information. Shotgun and 16S ribosomal RNA amplicon sequencing were performed on feces, whereas urine and fecal metabolites were analyzed by gas chromatography and liquid chromatography-mass spectrometry. Co-occurrence networks were generated based on significant Spearman correlations between data. Bile acid malabsorption (BAM) was identified in patients with diarrhea by retention of radiolabeled selenium-75 homocholic acid taurine.

RESULTS

Patients with IBS had significant differences in network connections between diet and fecal microbiomes compared with control individuals; these were accompanied by differences in fecal metabolomes. We did not find significant differences in fecal microbiota composition among patients with different IBS symptom subtypes. Fecal metabolome profiles could discriminate patients with IBS from control individuals. Urine metabolomes also differed significantly between patients with IBS and control individuals, but most discriminatory metabolites were related to diet or medications. Fecal metabolomes, but not microbiomes, could distinguish patients with IBS with vs those without BAM.

CONCLUSIONS

Despite the heterogeneity of IBS, patients have significant differences in urine and fecal metabolomes and fecal microbiome vs control individuals, independent of symptom-based subtypes of IBS. Fecal metabolome analysis can be used to distinguish patients with IBS with vs those without BAM. These findings might be used for developing microbe-based treatments for these disorders.

Canadian Association of Gastroenterology Clinical Practice Guideline on the Management of Bile Acid Diarrhea

BACKGROUND & AIMS

Chronic diarrhea affects about 5% of the population overall. Altered bile acid metabolism is a common but frequently undiagnosed cause.

METHODS

We performed a systematic search of publication databases for studies of assessment and management of bile acid diarrhea (BAD). The certainty (quality) of evidence and strength of recommendations were rated according to the Grading of Recommendation Assessment, Development and Evaluation approach. Patient population, intervention, comparator, and outcome questions were developed through an iterative process and were voted on by a group of specialists.

RESULTS

The certainty of evidence was generally rated as very low. Therefore, 16 of 17 recommendations are conditional. In patients with chronic diarrhea, consideration of risk factors (terminal ileal resection, cholecystectomy, or abdominal radiotherapy), but not additional symptoms, was recommended for identification of patients with possible BAD. The group suggested testing using ⁷⁵selenium homocholic acid taurine (where available) or 7α-hydroxy-4-cholesten-3-one, including patients with irritable bowel syndrome with diarrhea, functional diarrhea, and Crohn's disease without inflammation. Testing was suggested over empiric bile acid sequestrant therapy (BAST). Once remediable causes are managed, the group suggested cholestyramine as initial therapy, with alternate BAST when tolerability is an issue. The group suggested against BAST for patients with extensive ileal Crohn's disease or resection and suggested alternative antidiarrheal agents if BAST is not tolerated. Maintenance BAST should be given at the lowest effective dose, with a trial of intermittent, on-demand administration, concurrent medication review, and reinvestigation for patients whose symptoms persist despite BAST.

CONCLUSIONS

Based on a systematic review, BAD should be considered for patients with chronic diarrhea. For patients with positive results from tests for BAD, a trial of BAST, initially with cholestyramine, is suggested.

Canadian Association of Gastroenterology Clinical Practice Guideline on the Management of Bile Acid Diarrhea

Background and Aims

Chronic diarrhea affects about 5% of the population overall. Altered bile acid metabolism is a common but frequently undiagnosed cause.

Methods

We performed a systematic search of publication databases for studies of assessment and management of bile acid diarrhea (BAD). The certainty (quality) of evidence and strength of recommendations were rated according to the Grading of Recommendation Assessment, Development and Evaluation approach. Patient population, intervention, comparator and outcome questions were developed through an iterative process and were voted on by a group of specialists.

Results

The certainty of evidence was generally rated as very low. Therefore, 16 of 17 recommendations are conditional. In patients with chronic diarrhea, consideration of risk factors (terminal ileal resection, cholecystectomy or abdominal radiotherapy), but not additional symptoms, was recommended for identification of patients with possible BAD. The group suggested testing using ⁷⁵selenium homocholic acid taurine (where available) or 7α-hydroxy-4-cholesten-3-one, including patients with irritable bowel syndrome with diarrhea, functional diarrhea and Crohn's disease without inflammation. Testing was suggested over empiric bile acid sequestrant therapy (BAST). Once remediable causes are managed, the group suggested cholestyramine as initial therapy, with alternate BAST when tolerability is an issue. The group suggested against BAST for patients with extensive ileal Crohn's disease or resection and suggested alternative antidiarrheal agents if BAST is not tolerated. Maintenance BAST should be given at the lowest effective dose, with a trial of intermittent, on-demand administration, concurrent medication review and reinvestigation for patients whose symptoms persist despite BAST.

Conclusions

Based on a systematic review, BAD should be considered for patients with chronic diarrhea. For patients with positive results from tests for BAD, a trial of BAST, initially with cholestyramine, is suggested.

Methods for diagnosing bile acid malabsorption: a systematic review

BACKGROUND

Bile acid malabsorption (BAM) and bile acid-related diarrhea represent an under-recognized cause of chronic diarrhea mainly because of limited guidance on appropriate diagnostic and laboratory tests. We aimed to perform a systematic review of the literature in order to identify and compare the diagnostic accuracy of different diagnostic methods for patients with BAM, despite a proven gold standard test is still lacking.

METHODS

A PubMed literature review and a manual search were carried out. Relevant full papers, evaluating the diagnostic accuracy of different methods for BAM, were assessed. Available data were analyzed to estimate the sensitivity and specificity of each published test.

RESULTS

Overall, more than one test was considered in published papers on BAM. The search strategy retrieved 574 articles; of these, only 16 were full papers (with a total of 2.332 patients) included in the final review. Specifically, n = 8 studies used ⁷⁵Selenium-homotaurocholic-acid-test (⁷⁵SeHCAT) with a < 10% retention threshold; n = 8 studies evaluated fasting serum 7-α-hydroxy-4-cholesten-3-one (C4); n = 3 studies involved total fecal bile acid (BA) excretion over 48 h; n = 4 studies assessed fibroblast growth factor 19 (FGF19). ⁷⁵SeHCAT showed an average sensitivity and specificity of 87.32 and 93.2%, respectively, followed by serum C4 (85.2 and 71.1%) and total fecal BA (66.6 and 79.3%). Fasting serum FGF19 had the lowest sensitivity and specificity (63.8 and 72.3%). All the extracted data were associated with substantial heterogeneity.

CONCLUSIONS

Our systematic review indicates that ⁷⁵SeHCAT has the highest diagnostic accuracy for BAM, followed by serum C4 assay. The diagnostic yield of fecal BA and FGF19 assays is still under investigation. Our review reinforces the need for novel biomarkers aimed to an objective detection of BAM and therefore improving the management of this condition.

Diagnosis and management of bile acid diarrhoea: a survey of UK expert opinion and practice

OBJECTIVE

Bile acid diarrhoea (BAD), which includes bile acid malabsorption, causes a variety of digestive symptoms. Diagnostic rates and management vary considerably. We conducted a survey of current practice to review expert opinion and provide guidance on diagnosis and management.

DESIGN/METHOD

An online survey was conducted of clinical members of the UK Bile Acid Related Diarrhoea Network, who had all published research on BAD (n=21). Most were National Health Service consultants who had diagnosed over 50 patients with the condition.

RESULTS

The preferred terminology was to use BAD, with primary and secondary to classify causes. A wide range of presenting symptoms and associated conditions were recognised. SeHCAT (tauroselcholic acid) was the preferred diagnostic test, and 50% of respondents thought general practitioners should have access to this. Patients who met the Rome IV diagnostic criteria for functional diarrhoea, irritable bowel syndrome (IBS) with predominant diarrhoea or postcholecystectomy diarrhoea were usually investigated by SeHCAT, which was used sometimes in other types of IBS. Treatment with a bile acid sequestrant was offered to patients with low SeHCAT values, with expected response rates >70% in the most severe. Colestyramine was the usual sequestrant, starting between 2 g and 8 g daily; colesevelam was an alternative. In patients who had an incomplete response, increasing the dose, changing to an alternative sequestrant, use of loperamide and a low fat diet were suggested. Recommendations for follow-up and to improve the overall patient experience were made.

CONCLUSION

This expert survey indicates current best practice in the diagnosis and management of BAD.

75Se-Homocholic acid taurine scintigraphy (75SeHCAT®), a standard benchmark test in bile acid malabsorption?

Chronic diarrhoea due to bile acid malabsorption (BAM) is an underdiagnosed pathology. Different diagnostic tools are available. However, there is currently no consensus on which of these would be the benchmark test or gold standard. This review evaluates the possibility of using ⁷⁵Se-taurocholic acid (⁷⁵SeHCAT^®) scintigraphy as a benchmark diagnostic test and its perspective for the future. A literature review was conducted in Pubmed and OVID obtaining a total of 57 papers, 26 of which were finally used after being selected under the concepts of gold standard, diagnostic accuracy and other biomarkers. We evaluated the advantages and disadvantages of the different diagnostic tools: ¹⁴C-glycocholate, measurement of bile acids in faeces, C4 in serum, FGF19 in serum, cholestyramine, and ⁷⁵Se-tauroselcolic acid scintigraphy. We consider that the ⁷⁵SeHCAT^® scan is the most recommended diagnostic test in Europe for diagnosing BAM as it presents the highest values of sensitivity and specificity. It has a significant cost-benefit ratio, making it the test with the highest degree of recommendation. However, it is still not possible to use it in a recognised way as a gold standard due to the lack of studies that provide conclusive data that allow consensus. In the meantime, the combined use of cholestyramine testing in all patients we want to evaluate, regardless of the scintigraphy result, could be encouraged as a benchmark standard.

Pros and Cons of the SeHCAT Test in Bile Acid Diarrhea: A More Appropriate Use of an Old Nuclear Medicine Technique

Bile acid malabsorption (BAM) causing chronic diarrhea may be due to organic as well as functional disorders, and some of them were included under the general label of diarrheic-type irritable bowel syndrome (IBS-D). The 75-selenium homocholic acid taurine (SeHCAT) test is a nuclear medicine investigation considered to be the gold standard for the diagnosis of bile acid malabsorption (BAM). Many studies demonstrate that it could be effective in the clinical workout of chronic diarrhea due to different conditions. The SeHCAT test provides a quantitative assessment to estimate the severity of BAM and the possible response to therapy with bile acid sequestrants (BASs). However, there is no general agreement regarding its cutoff value and the test is not widely available. The aim of this review is to discuss the advantages and disadvantages of the SeHCAT test in clinical practice.

Guidelines for the investigation of chronic diarrhoea in adults: British Society of Gastroenterology, 3rd edition

Chronic diarrhoea is a common problem, hence clear guidance on investigations is required. This is an updated guideline from 2003 for the investigations of chronic diarrhoea commissioned by the Clinical Services and Standards Committee of the British Society of Gastroenterology (BSG). This document has undergone significant revision in content through input by 13 members of the Guideline Development Group (GDG) representing various institutions. The GRADE system was used to appraise the quality of evidence and grading of recommendations.

Obeticholic acid for severe bile acid diarrhea with intestinal failure: A case report and review of the literature

Bile acid diarrhea results from excessive amounts of bile acids entering the colon due to hepatic overexcretion of bile acids or bile acid malabsorption in the terminal ileum. The main therapies include bile acid sequestrants, such as colestyramine and colesevelam, which may be given in combination with the opioid receptor agonist loperamide. Some patients are refractory to conventional treatments. We report the use of the farnesoid X receptor agonist obeticholic acid in a patient with refractory bile acid diarrhea and subsequent intestinal failure. A 32-year-old woman with quiescent colonic Crohn’s disease and a normal terminal ileum had been diagnosed with severe bile acid malabsorption and complained of watery diarrhea and fatigue. The diarrhea resulted in hypokalemia and sodium depletion that made her dependent on twice weekly intravenous fluid and electrolyte infusions. Conventional therapies with colestyramine, colesevelam, and loperamide had no effect. Second-line antisecretory therapies with pantoprazole, liraglutide, and octreotide also failed. Third-line treatment with obeticholic acid reduced the number of stools from an average of 13 to an average of 7 per 24 h and improved the patient’s quality of life. The fluid and electrolyte balances normalized. The effect was sustained during follow-up for 6 mo with treatment at a daily dosage of 25 mg. The diarrhea worsened shortly after cessation of obeticholic acid. This case report supports the initial report that obeticholic acid may reduce bile acid production and improve symptoms in patients with bile acid diarrhea.

Challenging current views on bile acid diarrhoea and malabsorption

BACKGROUND

In 2012, the National Institute for Health and Care Excellence (NICE) assessed guidance (DG7) on the use of tauroselcholic (⁷⁵selenium) acid (also known as SeHCAT) for the investigation of diarrhoea due to bile acid malabsorption (BAM) in patients with IBS-D and in patients with Crohn's disease who have not had an ileal resection. NICE concluded that tauroselcholic (⁷⁵selenium) acid was recommended for use in research only. NICE will be reviewing the decision to update the guidance for tauroselcholic (⁷⁵selenium) acid, for these populations, in March 2017.

AIM

Our aim is to summarise advances in BAM, also known as bile acid diarrhoea (BAD), and encourage clinicians to re-evaluate their understanding of this disorder.

APPROACH

We review the prevalence, diagnosis and treatment of BAD/BAM. We describe the new evidence available since the original NICE review in 2012, and discuss the economic issues associated with failure to diagnose or to treat BAD/BAM accurately.

EVIDENCE UPDATE

There is new and compelling evidence available since DG7, which shows that tauroselcholic (⁷⁵selenium) acid scanning is a powerful tool in the diagnosis of BAD/BAM. We summarise published prevalence data (approximately 1% prevalence in the UK, as suggested by clinical practice diagnosis rates), and highlight that the true prevalence of BAD/BAM could be far greater than this.

CONCLUSION

We present evidence that challenges current opinion about this disorder, and we commend both clinicians and health technology assessment (HTA) agencies for being open to arguments and new evidence in any future HTAs.

A positive SeHCAT test results in fewer subsequent investigations in patients with chronic diarrhoea

Chronic diarrhoea is a common condition, resulting from a number of different disorders. Bile acid diarrhoea, occurring in about a third of these patients, is often undiagnosed. We hypothesised that a positive diagnosis of bile acid diarrhoea would reduce the need for subsequent investigations for alternative diagnoses.

METHODS

Patients previously recruited to a study of chronic diarrhoea who had selenium homocholic acid taurine (SeHCAT) testing and subsequent follow-up at our institution were identified. In a retrospective analysis, the numbers of defined investigations undertaken from the first 3 months after SeHCAT in the following 5 years were compared.

RESULTS

90 patients were identified with primary bile acid diarrhoea (SeHCAT retention <15%, n=36) or idiopathic diarrhoea (SeHCAT retention >15%, n=54). Follow-up had been performed on 29 and 39 subjects, respectively, with no differences in previous investigations or the last contact date. In the follow-up period, the proportions of these patients who had undergone endoscopic procedures (gastroscopy, colonoscopy and sigmoidoscopy) were the same. However, there was a higher proportion of patients in the SeHCAT-negative group who had other investigations, including imaging, physiological tests and blood tests (p=0.037). The use of cross-sectional imaging was significantly higher in this group (p=0.015) with greater proportions having CT (0.44 vs 0.10) and MRI (0.26 vs 0.07). Ultrasound use and the number of blood tests were higher in the SeHCAT-negative group whereas the SeHCAT-positive group attended more clinic appointments (p=0.013).

CONCLUSION

A positive diagnosis of bile acid diarrhoea, made by a SeHCAT test, resulted in reduced use of diagnostic investigations over the subsequent 5 years.

Multicentre prospective survey of SeHCAT provision and practice in the UK

Objective

A clinical diagnosis of bile acid malabsorption (BAM) can be confirmed using SeHCAT (tauroselcholic (⁷⁵selenium) acid), a radiolabelled synthetic bile acid. However, while BAM can be the cause of chronic diarrhoea, it is often overlooked as a potential diagnosis. Therefore, we investigated the use of SeHCAT for diagnosis of BAM in UK hospitals.

Design

A multicentre survey was conducted capturing centre and patient-level information detailing patient care-pathways, clinical history, SeHCAT results, treatment with bile acid sequestrants (BAS), and follow-up in clinics. Eligible data from 38 centres and 1036 patients were entered into a validated management system.

Results

SeHCAT protocol varied between centres, with no standardised patient positioning, and differing referral systems. Surveyed patients had a mean age of 50 years and predominantly women (65%). The mean SeHCAT retention score for all patients was 19% (95% CI 17.8% to 20.3%). However, this differed with suspected BAM type: type 1: 9% (95% CI 6.3% to 11.4%), type 2: 21% (95% CI 19.2% to 23.0%) and type 3: 22% (95% CI 19.6% to 24.2%). Centre-defined ‘abnormal’ and ‘borderline’ results represented over 50% of the survey population. BAS treatment was prescribed to only 73% of patients with abnormal results.

Conclusions

The study identified a lack of consistent cut-off/threshold values, with differing centre criteria for defining an ‘abnormal’ SeHCAT result. BAS prescription was not related in a simple way to the SeHCAT result, nor to the centre-defined result, highlighting a lack of clear patient care-pathways. There is a clear need for a future diagnostic accuracy study and a better understanding of optimal management pathways.

Assessment of intestinal malabsorption

Significant efforts have been made in the last decade to either standardize the available tests for intestinal malabsorption or to develop new, more simple and reliable techniques. The quest is still on and, unfortunately, clinical practice has not dramatically changed. The investigation of intestinal malabsorption is directed by the patient's history and baseline tests. Endoscopy and small bowel biopsies play a major role although non-invasive tests are favored and often performed early on the diagnostic algorithm, especially in paediatric and fragile elderly patients. The current clinically available methods and research tools are summarized in this review article.

A Multicenter Prospective Study to Investigate the Diagnostic Accuracy of the SeHCAT Test in Measuring Bile Acid Malabsorption: Research Protocol

Background

Bile acid malabsorption (BAM) is one possible explanation for chronic diarrhea. BAM may be idiopathic, or result from ileal resection or inflammation including Crohn’s disease, or may be secondary to other conditions, including cholecystectomy, peptic ulcer surgery, and chronic pancreatitis. No “gold standard” exists for clinical diagnosis of BAM, but response to treatment with a bile acid sequestrant (BAS) is often accepted as confirmation. The SeHCAT (tauroselcholic [selenium-75] acid) test uses a radiolabeled synthetic bile acid and provides a diagnostic test for BAM, but its performance against “trial of treatment” is unknown. Fibroblast growth factor 19 (FGF-19) and 7-alpha-hydroxy-4-cholesten-3-one (C4) also offer potential new biomarkers of BAM.

Objective

This protocol describes a multicenter prospective study to evaluate the diagnostic accuracy of SeHCAT and 2 biomarkers in predicting BAM as assessed by trial of treatment.

Methods

Participating gastroenterology centers should have a minimum workload of 30 SeHCAT patients per annum. Patients should not be pregnant, on medication that could confound follow-up, or have any severe comorbidity. All eligible patients attending a gastrointestinal appointment will be invited to participate. On attending the SeHCAT test, blood and fecal samples will be collected for analysis of FGF-19 by enzyme-linked immunosorbent assay and for C4 and fractionated bile acids by liquid chromatography–mass spectrometry. A capsule containing radiolabeled SeHCAT will be administered orally and a scan performed to measure SeHCAT activity. Patients will return on day 7 to undergo a second scan to measure percentage SeHCAT retention. The test result will be concealed from clinicians and patients. BAS will be dispensed to all patients, with a follow-up gastroenterologist appointment at 2 weeks for clinical assessment of treatment response and adherence. Patients responding positively will continue treatment for a further 2 weeks and all patients will have a final follow-up at 8 weeks. The diagnostic accuracy of the SeHCAT test and biomarkers will be analyzed at different thresholds using sensitivity, specificity, positive and negative predictive value, likelihood ratios, and area under the curve in a sample of 600 patients. Multivariable logistic regression models will be used to assess the association between presence of BAM and continuous SeHCAT retention levels after adjustment for confounders.

Results

Funding is being sought to conduct this research.

Conclusions

The SeHCAT test for diagnosis of BAM has been in common use in the United Kingdom for more than 30 years and an evidence-based assessment of its accuracy is overdue. The proposed study has some challenges. Some forms of BAS treatment are unpleasant due to the texture and taste of the resin powder, which may negatively affect recruitment and treatment adherence. Trial of treatment is not as “golden” a standard as would be ideal, and itself warrants further study.

Food, fibre, bile acids and the pelvic floor: An integrated low risk low cost approach to managing irritable bowel syndrome

Patients presenting with abdominal pain and diarrhea are often labelled as suffering from irritable bowel syndrome, and medications may be used often without success. Advances in the understanding of the causes of the symptoms (including pelvic floor weakness and incontinence, bile salt malabsorption and food intolerance) mean that effective, safe and well tolerated treatments are now available.

Systematic review with meta-analysis: the prevalence of bile acid malabsorption in the irritable bowel syndrome with diarrhoea

BACKGROUND

Irritable bowel syndrome is a widespread disorder with a marked socioeconomic burden. Previous studies support the proposal that a subset of patients with features compatible with diarrhoea-predominant IBS (IBS-D) have bile acid malabsorption (BAM).

AIM

To perform a systematic review and meta-analysis to assess the prevalence of BAM in patients meeting the accepted criteria for IBS-D.

METHODS

MEDLINE and EMBASE were searched up to March 2015. Studies recruiting adults with IBS-D, defined by the Manning, Kruis, Rome I, II or III criteria and which used 23-seleno-25-homotaurocholic acid (SeHCAT) testing for the assessment of BAM were included. BAM was defined as 7 day SeHCAT retention of <10%. We calculated the rate of BAM and 95% confidence intervals (CI) using a random effects model. The methodological quality of included studies was evaluated using the Quality Assessment for Diagnostic Accuracy Studies (QUADAS-2).

RESULTS

The search strategy identified six relevant studies comprising 908 individuals. The rate of BAM ranged from 16.9% to 35.3%. The pooled rate was 28.1% (95% CI: 22.6-34%). There was significant heterogeneity in effect sizes (Q-test χ(2)  = 17.9, P < 0.004; I(2)  = 72.1%). The type of diagnostic criteria used or study country did not significantly modify the effect.

CONCLUSIONS

These data provide evidence that in excess of one quarter of patients meeting accepted criteria for IBS-D have bile acid malabsorption. This distinction has implications for the interpretation of previous studies, as well as contemporaneous clinical practice and future guideline development.

Randomised clinical trial: colestyramine vs. hydroxypropyl cellulose in patients with functional chronic watery diarrhoea

BACKGROUND

Idiopathic bile acid malabsorption (BAM) has been suggested as a cause of chronic watery diarrhoea, with a response to colestyramine in 70% of patients. However, the efficacy of this drug has never been investigated in placebo-controlled trials.

AIM

To evaluate the efficacy of colestyramine as compared with hydroxypropyl cellulose in the treatment of functional chronic watery diarrhoea.

METHODS

Patients with chronic watery diarrhoea were randomly assigned to groups given colestyramine sachets 4 g twice daily (n = 13) or identical hydroxypropyl cellulose sachets (n = 13) for 8 weeks. The primary end-point was clinical remission defined as a mean of 3 or fewer stools per day during the week before the visit, with less than 1 watery stool per day. A secondary end-point was the reduction in daily watery stool number. SeHCAT test was performed in all patients, but an abnormal test was not a prerequisite to be included.

RESULTS

All included patients had a SeHCAT 7-day retention ≤20%. There were no statistical differences in the percentage of patients in clinical remission at week 8 between colestyramine and hydroxypropyl cellulose with either intention-to-treat (53.8% vs. 38.4%; P = 0.43) or per-protocol (63.6% vs. 38.4%; P = 0.22) analyses. However, the mean per cent decrease in watery stool number was significantly higher with colestyramine than with hydroxypropyl cellulose (-92.4 ± 3.5% vs. -75.8 ± 7.1%; P = 0.048). The rate of adverse events related to study drugs did not differ between groups.

CONCLUSIONS

Colestyramine (4 g twice daily) is effective and safe for short-term treatment of patients with chronic watery diarrhoea presumably secondary to BAM. Clinical Trials Register number EudraCT 2009-011149-14.

Effect of increased bile acid synthesis or fecal excretion in irritable bowel syndrome-diarrhea

OBJECTIVES

Approximately 25% of patients with irritable bowel syndrome-diarrhea (IBS-D) have increased total fecal bile acids (BA) and serum C4 (surrogate for BA synthesis). BA synthesis-related genes (KLB and FGFR4) are associated with colonic transit (CT) in IBS-D. Our aims were: (i) to compare phenotype and pathophysiology in IBS-D patients with increased or normal fecal excretion or synthesis of BA; and (ii) to explore association of variations in two candidate bile-acid synthesis genes (KLB and FGFR4) in these two subgroups of IBS-D.

METHODS

A total of 64 IBS-D patients underwent on one occasion: fasting serum C4 and FGF19, total fecal fat and BA excretion, CT, intestinal and colonic permeability, and candidate genotyping (rs17618244 (KLB), rs351855 (FGFR4)). Colonic sensation and tone were measured in 47 of the IBS-D patients. IBS-D subgroups were identified by fecal BA >2,337 mM per 48 h or by serum C4 >47.1 ng/ml.

RESULTS

IBS-D patients with fecal BA >2,337 mM per 48 h (19/54) had significantly greater body mass index, fecal fat, percent chenodeoxycholic acid (CDCA) in feces, and intestinal permeability, and borderline increased CT (P=0.13). Those IBS-D patients with serum C4 >47.1 ng/ml (13/54) had increased total fecal BA excretion and borderline increased colonic permeability. Variants in genes involved in feedback regulation of BA synthesis (KLB, P=0.06 and FGFR4, P=0.09) were potentially associated with the subgroup with elevated serum C4.

CONCLUSIONS

IBS-D with increased BA excretion or synthesis is associated with significant pathophysiological changes relative to patients with normal BA profile. BA diarrhea is identified more effectively with total fecal BA than with serum C4.