Getting Lost in the Pathophysiology of Inflammatory Bowel Disease

A recent review (JT Chang. NEJM 2020; 383: 2652-2664. Pathophysiology of Inflammatory Bowel Diseases) provides an in-depth description of the pathophysiology of inflammatory bowel disease (IBD). Digesting the article is akin to putting together a 1000 piece puzzle due to the complex interactions.

Some of the Key Points:

  • Based on genomewide association studies, there are “more than 240 risk variants that affect intracellular pathways recognizing microbial products (eg. NOD2); the autophagy pathway, which facilitates recycling intracellular organelles and removal of intracellular microorganisms (eg. ATG16L1); genes regulating epithelial barrier function (eg. ECM1); and pathways regulating innate and adaptive immunity (eg. IL23R and IL10).”
  • In this article, Figure 1 and 2 describe the intestinal mucosal immune system in health and disease. At baseline, this system promotes an antiinflammatory state “by virtue of active down-regulation of immune responses. For example, unlike macrophages in other parts of the body, intestinal macrophages do not produce inflammatory cytokines” after exposure to bacteria.

Other points:

  • Dysbiosis is present with IBD; however, studies have been “unable to infer causal relationships.”
  • Germ-free mice, when given fecal material from patients with IBD have increased susceptibility to colitis as compared to those who received fecal material from a healthy person.
    • Thus, this leads to potential for mitigating intestinal inflammation by modulation of the microbiome.
    • However, the authors note that humans are colonized by trillions of viral, fungal, bacterial, and eukaryotic microbes.
  • Other components of IBD pathophysiology: reduced mucus layer, increased microbial adherence, dysregulation of tight junctions/increased permeability, dysfunctional Paneth cells, TNF, IL23, IL12, IL6, IL 17A, IL17F, IL22, Interferon-gamma, integrins, JAK inhibitors, T-cells

My take: This article is a useful reference detailing the complexity of IBD pathophysiology and tries to summarize a whole textbook of information into 12 pages.

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Most Popular 2020 Posts

I want to thank all of you who take an interest in my blog, particularly those who give suggestions, references, and encouragement. The following posts were the most popular from the past year.

Related post: Favorite Posts of 2020

Sandy Springs at Sunrise

How Primary Sclerosing Cholangitis Alters Outcomes in Inflammatory Bowel Disease

PJ Trivedi et al. Gastroenterol 2020; 159: 915-928. Effects of Primary Sclerosing Cholangitis on Risks of Cancer and Death in People With Inflammatory Bowel Disease, Based on Sex, Race, and Age

Methods: The authors linked prospectively collected data from national health care registries maintained for all adults in England on hospital attendances, imaging and endoscopic evaluations, surgical procedures, cancer, and deaths.

Key findings:

  • Over 10 years, we identified 284,560 incident cases of IBD nationwide; of these, 2588 patients developed PSC. This study excluded patients <18 years of age.
  • Development of PSC was associated with increased risk of death and CRC (hazard ratios [HRs], 3.20 and 2.43, respectively; P < .001) and a lower median age at CRC diagnosis (59 y vs 69 y without PSC; P < .001)
  • Compared to patients with IBD alone, patients with PSC-IBD had a 4-fold higher risk of CRC if they received a diagnosis of IBD at an age younger than 40 years
  • Development of PSC also increased risks of cholangiocarcinoma (HR, 28.46), hepatocellular carcinoma (HR, 21.00), pancreatic cancer (HR, 5.26), and gallbladder cancer (HR, 9.19) ( P < .001 for all)
  • The greatest difference in mortality between the PSC-IBD alone group vs the IBD alone group was for patients younger than 40 years
  • Patients with PSC-UC had >40% risk of colonic resection compared to patients with IBD alone (aHR 1.65)

My take: This study shows the impact the added diagnosis of PSC has for patients with IBD. One of the limitations in assessing outcomes is determining whether someone with IBD has PSC as there are a lot of patients with IBD who have asymptomatic changes in their biliary tree.

Related blog posts:

The Link Between Celiac Disease and Inflammatory Bowel Disease

IM Pinto-Sanchez et al. Gastroenterol 2020; 159: 884-903. Association Between Inflammatory Bowel Diseases and Celiac Disease: A Systematic Review and Meta-Analysis

Methods: The authors identified 65 relevant studies after searching databases including MEDLINE, EMBASE, CENTRAL, Web of Science, CINAHL, DARE, and SIGLE through June 25, 2019 for studies assessing the risk of CeD in patients with IBD, and IBD in patients with CeD

Key findings:

  • Among patients with celiac disease, there was an increased risk of IBD vs controls (RR 9.88; 95% CI 4.03–24.21); the risk was greater for Crohn’s disease than ulcerative colitis
  • Among patients with inflammatory bowel disease, there was an increased risk of celiac disease vs controls (risk ratio [RR] 3.96; 95% confidence interval [CI] 2.23–7.02); however, this finding needs to be interpreted with a lot more caution.
    • The population-based studies that identified this risk relied on ICD codes.
    • Celiac diagnosis is much more difficult in patients with IBD. Overdiagnosis is possible due to increased surveillance, and misinterpretation of serology (eg. false positive serology). In addition, the pooled prevalence in this study of 0.75%, while greater than the controls of 0.3%, remains lower that the current worldwide prevalence of approximately 1%.
    • Only more prospective cohort studies will prove a definitive increase in risk.

My take: In patients with either IBD or celiac disease, clinicians should consider additional diagnoses in patients with ongoing symptoms.

Anemia in IBD -NASPGHAN Position Paper

A Goyal et al. JPGN 2020; 71: 563-582 Full text (free). Anemia in Children With Inflammatory Bowel Disease: A Position Paper by the IBD Committee of the North American Society of Pediatric Gastroenterology, Hepatology and Nutrition.

Main Types of Anemia in Inflammatory Bowel Disease:

  • “IDA is the most common cause of anemia in children with IBD. True iron deficiency results from a number of factors, including chronic blood loss secondary to gastrointestinal bleeding, decreased iron absorption because of tissue or systemic inflammation and from reduced absorptive surface area. “
  • “Functional iron deficiency (FID) results from high levels of circulating hepcidin, which binds to and disables the iron transporter, ferroportin. Under the influence of hepcidin, ferroportin-mediated export of intracellular iron is stalled, leaving the iron trapped within the enterocytes and macrophages… the underlying inflammation, which induces hepcidin production can result in anemia secondary to FID.”
  • Anemia of chronic disease (ACD) “occurs from various downstream pathways secondary to inflammation.”

Table 4:

Recommended Testing

  • Screening Tests: “initially a complete blood count (CBC), CRP, and ferritin levels should be performed. If a patient is found to be anemic, then testing should include CBC with differential, including mean corpuscular volume (MCV), mean corpuscular Hgb concentration (MCHC), red cell distribution width (RDW), reticulocyte count, CRP, serum ferritin, and transferrin saturation (TSAT)”
  • Serum iron level … is … unreliable in the assessment of iron deficiency as the level fluctuates with several variables.
  • Transferrin saturation (TSAT) is a measure of the iron content in the circulating transferrin and reflects the availability of utilizable iron

Treatment of Anemia

  • In mild anemia (Hgb ≥10 g/dL) and/or quiescent disease, oral iron should be tried first.
  • Parenteral iron is indicated when oral iron is ineffective or poorly tolerated, in patients with moderate-severe anemia and/or with active inflammation.
  •  According to ECCO guidelines, an IV replacement goal of achieving of ferritin level of up to 400 μg/L is more likely to prevent recurrence of anemia…a transferrin saturation of 50% and serum ferritin of 800 μg/L should not be exceeded
  • Regarding iron effects on microbiome: studies indicate that dysbiosis at baseline worsens the unfavorable shifts in microbiome with oral iron therapy…Our position, however, is that further studies are required in humans before any reliable conclusions can be drawn. [My question: have the effects of oral iron supplementation on the microbiome been compared to IV iron supplementation on the microbiome?]
  • Table 6 lists various iron products including costs and dosing.
  • The hypersensitivity reactions to parenteral iron are mostly secondary to iron nanoparticles that trigger complement activation-related pseudo-allergy (CARPA)….It is important that parenteral iron be administered by trained personnel. Emergency medications and resuscitative equipment should be available during these infusions.

My take: This is a useful resource for a very common problem.

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Disclaimer: This blog, gutsandgrowth, assumes no responsibility for any use or operation of any method, product, instruction, concept or idea contained in the material herein or for any injury or damage to persons or property (whether products liability, negligence or otherwise) resulting from such use or operation. These blog posts are for educational purposes only. Specific dosing of medications (along with potential adverse effects) should be confirmed by prescribing physician.  Because of rapid advances in the medical sciences, the gutsandgrowth blog cautions that independent verification should be made of diagnosis and drug dosages. The reader is solely responsible for the conduct of any suggested test or procedure.  This content is not a substitute for medical advice, diagnosis or treatment provided by a qualified healthcare provider. Always seek the advice of your physician or other qualified health provider with any questions you may have regarding a condition

Diagnostic Strategy For Children with Diarrhea and Abdominal Pain

A recent study (E Van de Vijver et al. Pediatrics 2020; 146: e20192235) shows a logical approach for testing children with diarrhea and abdominal pain.

Abstract and video abstract link: Test Strategies to Predict Inflammatory Bowel Disease Among Children With Nonbloody Diarrhea

Methods:

  • Prospective cohort study: n=193, 6 to 18 years who underwent a standardized diagnostic workup.
  • Patients with rectal bleeding or perianal disease were excluded because the presence of these findings prompted endoscopy regardless of their biomarkers.
  • In addition to symptoms, objective measures included C-reactive protein (>10 mg/L), hemoglobin (<−2 SD for age and sex), and fecal calprotectin (≥250 μg/g).

Key findings:

  • Twenty-two of 193 (11%) children had IBD
  • “Triaging with a strategy that involves symptoms, blood markers, and calprotectin will result in 14 of 100 patients being exposed to endoscopy. Three of them will not have IBD, and no IBD-affected child will be missed.

My take: The approach advocated by the authors of reserving a diagnostic endoscopy for children at high risk for IBD based on stool tests/blood tests in addition to symptoms has merit.  I would add a couple caveats:

  1. In this population, I would recommend checking for celiac disease (eg. tissue tranglutaminase IgA antibody, serum IgA level)
  2. I think in individuals with ‘borderline’ elevations of calprotectin (50-250 μg/g), followup testing is needed and if remains persistently elevated, then ileocolonoscopy is likely warranted.  (Calprotectin values in younger children tend to be higher -so this approach is best suited in children >5 years of age)

Related blog posts:

Nutrition4Kids and Nutrition4IBD

My colleague and partner, Stan Cohen, along with his outstanding advisory board, have put together two terrific (free) resources for both children and adults:

Both are up-to-date, user-friendly, authoritative and attractive websites that feature advice families can trust to help them understand their disease and options to live as full a life as possible. Between the two, there are:

  • Over 700 articles
    • Nutrition4Kids Categories: Eating at different ages, Healthy lifestyle, Nutrients, Diseases and disorders and Patient experience
    • Nutrition4IBD Categories: Understanding IBD, Treatment Options, Nutrition for IBD and Patient options.
  • Over 60 videos including 35 on food allergies (including FPIES and eosinophilic disorders) and 14 on tube-feedings, including one about a lacrosse player that is quite inspirational.
  • Amazing tools:
    • A food log and a symptom diary that patients can download to record how they are doing
    • a BMI calculator
    • a table of milk alternatives (created by our nutritionist Bailey Koch)
    • a tool which provides over 150,000 food labels for restaurant and packaged foods.
    • a cool tool where a patient can indicate their age, gender, whether they’re breastfeeding or pregnant (even which trimester they’re in), and it will tell what’s in over 200,000 foods and what nutrients and calories they need.
  • Healthy recipes with their nutrient values per serving.
  • This website relies on a group of 42 contributors including many from our group, psychologists, speech-language pathologists, nurses, dietitians, and families.
  • Other practices can link to our site, so they can share our medically-curated and accurate content and tools with their patient-families.

What is the Current Standard of Care for PPE and Endoscopy Cases?

CC Thompson et al. Gastointestinal Endoscopy (EPUB), in a letter to the editor, respond to two recent studies on SARS-CoV-2 virus/COVID-19 and provide recommendations for PPE use in this era of COVID-19.

Here’s a link to manuscript: COVID-19 in Endoscopy: Time to do more?

Key points:

  • Reduce non-urgent cases. “We have cut our daily endoscopy volume by over 80% and closed our ambulatory endoscopy practice.”
  • Increase the use of telemedicine. “At present, telemedicine or virtual visits make up 91% of our upcoming clinic appointments.”
  • Physical distancing as advocated recently by WHO throughout a patient’s time in the endoscopy unit is stressed in the papers, with a 6-foot minimum between individuals.
  • Suggests “the need for a separate toilet as part of the isolation to minimize spread of infection due to bioaerosols from the toilet plume”
  • Our hospital system has recently changed policy to mandate that all employees wear surgical masks at all times while in the hospital and attest to their wellness online before reporting to work.
  • We suggest labeling each computer so the same provider uses that computer and chair for the entire day, and separating by at least 6 feet.
  • All endoscopic procedures (upper endoscopy, colonoscopy, EUS, ERCP) are aerosol-generating, referencing studies that show contamination of the endoscopist’s face during routine procedures. This makes all endoscopic procedures high risk from an infectious standpoint, and appropriate PPE is
    recommended… It makes little sense for healthcare providers to perform
    aerosolizing procedures, with patients coughing or passing gas on them, while not wearing an N95 mask or better
  • “It is important to use full PPE for all endoscopic procedures while in a pandemic such as this especially in areas with community spread, because no one is truly low risk given our ongoing difficulties with testing.”
  • “The mask can be reused as long as it is functional, not soiled, and not used in a suspected or COVIDpositive patient. It is important to cover the N95 to prevent soiling.”
  • “A study from China showed that no medical staff working in high-risk departments who wore N95s and practiced strict hand hygiene regardless of patient’s infection status became infected.”
  • “Testing all patients before high-risk procedures such as endoscopy is likely the best approach; however, this will depend on significant expansion of testing capabilities. Hopefully, the development of point-of-care testing with rapid results and increasing testing availability will make this a reality soon”

My take (in part from authors): “We are living through an unprecedented time and are all trying our best to protect our patients and ourselves under suboptimal conditions of limited PPE, limited testing, and limited data. ”  The recommendations in this article are based mainly on expert opinion and may need modifications based on new data and circumstances.

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IOIBD (International Organization for the Study of Iinflammatory Bowel Disease) Recommendations (#76) for IBD Patients with Regard to COVID-19:

Full link: IOIBD Update on COVID19 for Patients with Crohn’s Disease and Ulcerative Colitis (3/26/20)

 

 

IBD Shorts February 2020

Cost of IBD Care is Increasing. From Healio Gastro: Chronic inflammatory disease expenditures nearly double over last 2 decades Reference: Click B, et al. Poster 22. Presented at: Crohn’s and Colitis Congress; Jan. 23-25, 2020; Austin, Texas

An excerpt from Healio Gastro summary: [Using] the Medical Expenditure Panel Survey (MEPS), a nationally representative database of health care use and expenditure data collected since 1998The researchers assessed total annual, outpatient, inpatient, emergency and pharmacy expenditures in both patients with IBD (n = 641) and RA (n = 641). They used three separate time periods – 1998-2001, 2006-2009 and 2012-2015 –to compare expenditures over time…

Median per-patient annual health care expenditure in patients with IBD was $6,570 compared with $4,010 in patients with RA across all years of the study. Total annual spending increased approximately 2.2 times (95% CI, 1.6-3; P < .01) over the study period and was 36% higher in IBD than RA (P = 0.01).

Pharmaceutical spending increased more than fourfold (95% CI, 3.2-6.1; P < .01) and became the largest cost category (44% total). However, inpatient expenses in IBD decreased 40% over the study period.

My take: While the cost has increased, these new treatments are improving outcomes.  With the emergence of biosimilars, there may be improvement in pharmaceutical spending.

More on Proactive Therapeutic Drug Monitoring (pTDM) Being Helpful: SR Fernandes et al. Inflamm Bowel Dis 2020; 26: 263-70, editorial 271-2.  In this study, a prospective group of patients (n=56) undergoing pTDM were compared with a historical control group (n=149). pTDM had less frequent surgery (9% vs. 21%) and higher rates of mucosal healing (73% vs. 39%).  Treatment escalation was 3 times more common with pTDM than in the control group.

Increased risk of VTE in IBD patientsJD McCurdy et al. Inflamm Bowel Dis 2020; https://doi.org/10.1093/ibd/izaa002

Abstract Link: Risk of Venous Thromboembolism After Hospital Discharge in Patients With Inflammatory Bowel Disease: A Population-based Study

In a population-based study from Ontario, the authors analyzed a total of 81,900 IBD discharges (62,848 nonsurgical and 19,052 surgical) which were matched to non-IBD controls… The cumulative incidence of VTE at 12 months after discharge was 2.3% for nonsurgical IBD patients and 1.6% for surgical IBD patients…Nonsurgical IBD patients and surgical patients with ulcerative colitis are 1.7-fold more likely to develop postdischarge VTE than non-IBD patients.

Good Food and Bad Food for Crohn’s Disease -No Agreement

As noted in a previous blog (IBD Briefs August 2019), there have been numerous diets proposed to help with Crohn’s disease.   The chart below illustrates the lack of any consensus.

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