Caution with Celiac Genetic Testing Plus Two

Conventional wisdom and previous studies have indicated that negative testing for HLA-DQ8 and HLD-DQ2.5 alleles makes a diagnosis of celiac disease (CD), now or in the future, very unlikely.  While ~60% of the population has one of these alleles, testing negative for these alleles has been regarded as having a high negative predictive value (>99%) and can be valuable in cases of equivocal diagnosis.

The authors of recent report (F Fernandez-Banares et al. Clin Gastroenterol Hepatol 2017; 15: 594-96) challenged this wisdom, noting that there is expected to geographical variation in the presence of these alleles. The goal of their study was to assess the prevalence of HLA-DQ2.5/8 among CD patients in Spain by reviewing previous studies; 12 studies were included. To be included, patients had to have villous atrophy, positive serology and available genotyping.

Key finding:

  • Among 2963 Spanish CD patients, 3% “might be negative for HLA-DQ2.5/8.”

This is a brief report.  It is expected that limitations would relate to the accuracy of genotyping and of excluding other causes of villous atrophy.

My take: (from the authors) “This information highlights the need to be cautious when ruling out CD only on the basis of genetics.”

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Briefly noted:

L Kivela et al. J Pediatr 2017; 183: 115-21.  This study divided children with CD into those identified via screening (n=145) and those identified due to clinical symptoms (n=359). Key findings:

  • There were no differences in serology or histology between the two groups
  • More than half (51.8%) of screen-detected patients had symptoms at diagnosis, but typically these were milder than in the clinically-detected group.
  • Anemia was more common in the ‘clinical group’ 22.9% vs 7.1% (screen group) as was poor growth (36.9% vs. 15.7%).

AJ Irvine et al. Am J Gastroenterol 2017; 112: 65-76. (Thanks to Ben Gold for this reference) In this systemic review with 15,256 individuals (& 9,275 with irritable bowel), “prevalence of positive celiac serology and biopsy-proven CD was significantly higher in subjects with symptoms suggestive of IBS vs. healthy controls.”  The odds ratio for serology-positive and/or biopsy-proven CD ranged from 2.75 to 4.48, though there was no significant increase in these ORs for North American studies.

Palace of Versailles

 

FDA Warning on Eluxadoline (Viberzi)

Briefly noted: The FDA has issued a safety warning for patients with irritable bowel syndrome who have had their gallbladder removed.

FDA Warns of Increased Risk of Serious Pancreatitis with irritable bowel drug eluxadoline (Viberzi) in patients without a gallbladder

An excerpt:

Viberzi is a prescription medicine used to treat irritable bowel syndrome in adults when the main symptom is diarrhea (IBS-D)…From May 2015, when Viberzi was first approved, through February 2017, FDA received 120 reports of serious cases of pancreatitis or death.* Among the 68 patients who reported their gallbladder status, 56 of them did not have a gallbladder and received the currently recommended dosage of Viberzi. Seventy-six patients were hospitalized, of which two patients died.

My take: Now that this warning has been issued, there may be additional cases identified. While this medication is mainly used in adults, pediatric gastroenterologists need to be aware of this risk in counseling potential patients.

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Palace of Versailles -fountain turned off!

 

Two for the PPI Team

Medicine safety is not nearly as straight-forward as most people would expect.  Virtually all medicines have the potential for adverse reactions.  In addition, there are often conflicting reports on how frequent adverse reactions occur; furthermore, negative studies demonstrating safety may be published less frequently due to publication bias.

This problem is compounded by the frequent misunderstanding of statistics.  Frequently, risks of medications are expressed as an odds ratio.  So, if an adverse reaction occurs twice as often with the medication than without the medication, the odds ratio would 2.0.  Yet, if the adverse reaction is rare (eg. one in a million), then the absolute increase in risk remains minuscule.

Proton pump inhibitors have received a lot of press, often about rare increases in adverse reactions. But, there are many potential benefits to these medications and numerous studies demonstrating fairly good safety profiles.  A few more studies (thanks to Ben Gold for these references) on their safety have recently been published:

  • 1. “Long-term Proton Pump Inhibitor Use is Not Associated with Changes in Bone Strength and Structure” LE Targownik et al. Am J Gastroenterol 2017; 112: 95: 101.
  • 2. “Proton Pump Inhibitors Do Not Increase Risk for Clostridium difficile Infection in the Intensive Care Unit.” DM Faleck et al. Am J Gastroenterol 2016; 111: 1641-8.

In the first study, the authors examined 52 PPI-users (>5 yrs) and 52 non-PPI users with mean age of 65 years.  They underwent quantitative CT , DXA, and markers of bone metabolism. “There were no differences detected..between the two groups.”  The conclude that PPIs were not associated with changes that increase a risk of fracture and “provide further evidence that the association between PPI use and fracture is not causal.”

In the second study, the authors analyzed data from 14 ICUs 2010-2013 and identified 18,134 patients (mean age 66-67 yrs) who met inclusion criteria.  271 (1.5%) developed Clostridium difficile infection (CDI) in the ICU.  The main risk factor for CDI was antibiotics with adjusted Hazard Ratio (aHR) of 2.79.  “There was no significant increase in risk for CDI associated with PPIs in those who did not receive antibiotics (aHR 1.56; 95% CI, 0.72-3.35).”  “PPIs were actually associated with a decreased risk for CDI in those who received antibiotics (aHR 0.64; 95% CI 0.48-0.83).”  The authors also noted that even those who received the highest doses of PPIs, “there was no risk for health-care facility-onset CDI.”

My take: PPIs can be life-saving medications and can alleviate a lot of suffering.  These studies pushback on some of the concerns about PPI risk.

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The Coronation of Napoleon (Louvre); Jacques-Louise David

Correlation between Microbiome and Irritable Bowel Syndrome

I vaguely remember jokes that I heard as a teenager about computers that could analyze stool or urine and then come to remarkable conclusions about the person’s health or extramarital problems.  Fast-forward a few decades and these jokes are not so far off.

A recent study (J Tap, M Derrien, et al. Gastroenterol 2017; 152: 111-23) describes an intestinal microbiome ‘signature’ associated with severity of irritable bowel syndrome (IBS).  Thanks to Ben Gold for highlighting this article.  (He placed this one on my desk: “Jay -FYI -It is all about the poop!”)

In this study, the authors collected fecal and mucosal samples from adult patients who met Rome III criteria for IBS.  They started with an exploratory set of 149 subjects (110 with IBS, 39 controls).  Subsequently, they used a validation cohort of 46 subjects (29 with IBS, 17 controls).

Key findings:

  • “By using classic approaches, we found no differences in fecal microbiota abundance or composition between patients with IBS vs healthy patients.”  But, “a machine learning procedure, a computational statistical technique, allowed us to reduce the 16S ribosomal RNA data complexity into a microbial signature for severe IBS, consisting of 90 bacterial operational taxonomic units.”
  • This microbial signature showed IBS to be associated negatively with microbial richness, exhaled CH4, presence of methanogens, and enterotypes enriched with Clostridiales or Prevotella species.  Figure 6 provides a graphic summary of the study and the microbial signature.
  • The authors note their findings were not explained by differences in diet or medications.
  • Overall, the microbial signature has a low sensitivity and thus at this point does not have clinical applicability.

My take: There are a number of studies showing that our gut microbiome is associated with numerous conditions, including IBS, inflammatory bowel disease, and metabolic syndrome.  Having our poops analyzed by a computer to tell us what is wrong does not seem all that funny anymore.

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Bridge on Seine River

Image Only: Living with Irritable Bowel Syndrome

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Image Only: Candida Esopagitis

In a patient who presented with trouble swallowing, his endoscopy showed candida esophagitis.  “Oral antifungal therapy was initiated in the patient, and within 2 weeks after starting therapy, his pain on swallowing was reduced. A repeat endoscopy performed 12 weeks after the initiation of antifungal therapy showed a marked reduction in the number and severity of esophageal lesion.”

FDA Approves Plecanatide (Trulance) for Adults with Idiopathic Constipation

Here’s the link: FDA approves Trulance for Chronic Idiopathic Constipation (Jan 19.2017).  Plecanatide is a guanylate cyclase-C agonist.

An excerpt:

Trulance, taken orally once daily, works locally in the upper GI tract to stimulate secretion of intestinal fluid and support regular bowel function.

The safety and efficacy of Trulance were established in two 12-week, placebo-controlled trials including 1,775 adult participants. Participants were randomly assigned to receive a placebo or Trulance, once daily. Participants in the trials were required to have been diagnosed with constipation at least six months prior to the study onset and to have less than three defecations per week in the previous three months, as well as other symptoms associated with constipation. Participants receiving Trulance were more likely to experience improvement in the frequency of complete spontaneous bowel movements than those receiving placebo, and also had improvements in stool frequency and consistency and straining.

Trulance should not be used in children less than six years of age due to the risk of serious dehydration… The safety and effectiveness of Trulance have not been established in patients less than 18 years of age.

The most common and serious side effects of Trulance was diarrhea.

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