Category Archives: Pediatric Gastroenterology Intestinal Disorder

Linaclotide –not for kids

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Linaclotide has been approved for adults (≥18 years) with chronic constipation and constipation-predominat irritable bowel syndrome (IBS-C) (Gastroenterol & Hepatol 2012; 8: 653-60).

Linaclotide is a 14-amino acid peptide that stimulates guanylyl cyclase C (GCC) receptors.  It mimics the endogenous peptides guanylin (15 amino acids) and uroguanylin (16 amino acids) which activate GCC through a cascade which activates CFTR to increase luminal levels of bicarbonate, chloride and water.  This in turn improves gastrointestinal transit.

There were several trials undertaken to assess the efficacy of linaclotide in IBS-C:

  • 47 patients (36 women) with IBS-C were treated with linaclotide (100 μg or 1000 μg) or placebo –5 day study. The 1000 μg dose significantly decreased colonic transit time compared with placebo.  No serious adverse events were reported.
  • 420 patients were enrolled in a 12-week, randomized, double-blind, placebo-controlled, dose-ranging study.  The population was 92% female, 80% caucasian with a mean age of 44 years.  337 patients completed the study.  There were improvements in the number of complete spontaneous bowel movements (CSBMs) per week and in abdominal pain.  Additional results:
  1. With 300 μg dose, there were 3.93 CSBMs/week, with150 μg dose 2.79 CSBMs/week compared with 1.47 for placebo.
  2. With 300 μg dose, there was -0.90 in pain score, with 150 μg dose -0.71 compared with -0.49 for placebo.  Overall, abdominal pain improved in 31.1-38.7% of linaclotide-treated patients compared with 22.7% of placebo-treated patients.

For chronic constipation, four trials (n=42, n=310, n=630, and n=642) have shown increased CSBMs/week.  On average, a dose of 290-300 μg dose resulted in 1.8-2.7 CSBMs/week, a dose of 145-150 μg dose resulted in 1.6-2.0 CSBMs/week compared with 0.5-0.6 CSBMs/week for placebo.  Changes in stool frequency were also reflected in quality of life scores.  When linaclotide was stopped, patients reverted to similar stooling rates as placebo-treated patients but no rebound effects were noted.

Prior to approval of linaclotide, lubiprostone (Amitiza) had been the only FDA-approved medication for IBS-C.  For chronic constipation, polyethylene glycol is another approved treatment.

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More frequent pediatric IBD

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Using a national cohort of prospective and retrospective data on pediatric inflammatory bowel diagnosis, (PIBD) a recent report indicates a rising incidence of PIBD in Scotland (Inflamm Bowel Dis 2012; 18: 999-1005).

Key findings:

  • Between 2003-2008, 436 patients were diagnosed with PIBD; this equates to 7.82/100,000; Crohn’s was 4.75 and UC 2.06 per 100,000 respectively
  • Between 1990-1995, 260 patients were diagnosed with PIBD; this equates to 4.45/100,000; Crohn’s was 2.86 and UC 1.59 per 100,000 respectively
  • Mean age of diagnosis in more recent cohort was younger: 12.7 years compared with 11.9 years

Currently, a data-base coordinated in a single center along with collaboration with regional networks enables the capture of all new IBD diagnosis (since 1999).  Prior cohort was determined by “exhaustive examination” of previous IBD records.

Running out of options

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A series of articles on natalizumab were published which give practical advice for this drug which clinicians often turn to when ‘running out of options’ (Gastroenterol Hepatol 2012; 8: 4-17).

Slides from these articles should be available soon (not online on 1/2/13):

http://www.clinicaladvances.com/index.php/our_publications/gastro_hep-issue/gh_november_2012/

According to an algorithm on page 7, in patients with moderate-severe Crohn’s disease who have failed conventional therapies and anti-TNF drugs (or unable to tolerate), the next step is to obtain anti-JCV (John Cunningham Virus) antibody status.  Patients who test negative are ‘Okay to treat with natalizumab’ due to very low risk of progressive multifocal leukoencephalopathy (PML).  Repeated testing at least once a year is then recommended.

For patients who test positive for anti-JCV at any time point, natalizumab can be considered if no other treatment options are available, but the risk of PML is much greater. Previous blog entries (below) have discussed this in greater detail and have provided additional references:

Another article published the experience in 36 Mayo clinic patients between April 2008-September 2010 (Inflamm Bowel Dis 2012; 18: 2203-08).  Consecutive patients who received natalizumab were prospectively followed.  Of the 36 treated with natalizumab, 30 agreed to participate in the study.  23 patients had failed two anti-TNF agents and 7 had failed one anti-TNF agent.  Median age was 35 years.

Results:

  • 14 (46%) had a complete clinical response, 12 had a partial response, and four had no response.  Cumulative probability of a complete response within 1 year was 56%.
  • Time to response: 10% after 1st dose, 50% of patients had complete response after 4th dose
  • Adverse events were common –though this rarely caused drug cessation. Common events included headache and infections (listed in Table 4 of article).  Some infections prompted holding natalizumab for up to 8 weeks.
  • 11 stopped natalizumab due to lack of improvement.

Teduglutide for Short Bowel Syndrome

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More data on teduglutide indicate its potential for short bowel syndrome (SBS) (Gastroenterol 2012; 143: 1473-81, editorial 1416-20).  Treatments for SBS are needed.  One year of parenteral nutrition often costs the health care system in excess of $100,000 per year.  This cost does not account for laboratory studies, health care visits, complications, and hospitalizations.  Treatment of intestinal failure with transplantation “may cost upwards of $1 million.”

In this study of adult patients with an average of 50 years, teduglutide was given in a prospective randomized double-blind study to 42 patients and another 43 patients received placebo. The dose of 0.05 mg/kg/day via subcutaneous injection was chosen based on a previous trial which showed that a higher dose was less effective.  Among these patients, the most common reasons for SBS were vascular disease (34%), Crohn’s disease (21%), volvulus (11%), and injury ((9%).

Bottom line:

  • Teduglutide over a 24-week study was more effective than placebo.  63% of study patients had a drop in parenteral nutrition requirement of more than 20% compared with only 30% of the placebo group.
  • The mean reduction in parenteral nutrition support of teduglutide-treated patients was 4.4 L/week compared with 2.3 L/week for placebo-treated patients.
  • Citrulline, a biomarker of mucosal mass, was increased in the teduglutide group.  In the treatment group, citrulline increased by 20.6 μmol/L compared with 0.7 μmol/L for the placebo group.

How does teduglutide work?  Teduglutide is a much more stable analog of glucagon-like peptide-2 (GLP-2).  The latter is released by the distal small bowel and colon.  GLP-2 promotes intestinal epithelial growth and increases transit time.

What are the adverse effects of teduglutide? First, there is a concern that teduglutide could promote colonic adenomas based on studies in mice.  GLP-2 receptors are present in the lung, and brain (including hypothalamus); its effects in these areas is poorly understood.  In addition, abdominal pain, distention, nausea, peripheral edema, and nasopharyngitis were more common in the treatment group. The long-term consequences of teduglutide therapy are not known.

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Quality improvement and better outcomes in Pediatric Inflammatory Bowel Disease

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More information on outcomes and quality improvement (QI) efforts are available from Cincinnati Children’s Hospital (JPGN 2012; 55: 679-88).  The QI efforts at Cincinnati are part of a broader effort in QI in pediatric IBD that has been discussed on a previous post (see below).

Our group has rejoined Improve Care Now (ICN) and I look forward to gaining more first hand experience.  Some of the ICN target goals:

  • 80% remission rate among each center and sustained remission rate of 45%
  • 76% steroid-free remission
  • 90% checking TPMT if using thiopurine
  • 95% checking PPD/chest xray if using biologic therapy
  • 95% using accepted methotrexate dosing

As I look at these goals, I wonder whether the remission rate is feasible and about the variation in different centers. For example, among the groups with >75% enrollment of their patients, one center reports a 89% remission rate and another center 64% remission rate.  Given the limited number of therapeutic agents, how could there be such a difference?  Some explanations could include variation in the use of more potent biologic agents as well as capturing/assuring followup of more patients who are doing well.

Given this backdrop, I looked at this most recent publication to learn how their QI practices could translate into better care for my patients.

In this retrospective chart review study of 505 patients, who were followed from 2007-2010 at the IBD center, the remission rate increased from 59% to 76%.  The data were captured prospectively.  This corresponded to improved patient global assessment (>7) from 69% to 80%.  Repeated steroid use dropped from 17% to 10%.  Vitamin D (25-OH D) improved and this also correlated with quiescent disease.

Remission rates were defined by a pediatric Crohn clinical disease index, the sPCDAI, or PUCAI for Ulcerative colitis.

Key observations:

  • There was a trend towards increased use of anti-TNFα therapy (along with decreased use of 6-mercaptopurine) during the study period, but this did not reach statistical significance. No statistical difference was identified in the use of any major IBD medication class.
  • Despite target goals, the only drug class with a statistically significant change in dosing was 5-ASA (from 42 mg/kg to 50 mg/kg).
  • Fecal calprotectin monitoring increased.  The QI team recommended that IBD patients with ‘inactive’ disease have a fecal calprotectin measured every 6 months.  Those with elevated values had therapeutic drug monitoring implemented.  “Fecal calprotectin >400 μg/g is associated with a higher chance of relapse in a pediatric cohort.”
  • Starting in 2009, increased vitamin D monitoring was implemented (every 6 months).  In patients with a serum 25-OHD level < 30 ng/mL, treatment with 50,000 units weekly (for 6-8 weeks) was recommended (8000 units if weight <20 kg).  Once serum 25-OHD was >30 ng/mL, patients were maintained on monthly dosing.
  • Preclinic planning also increased and corresponded to improved remission rates which were 67% in 2009 and 76% in 2010.
  • The authors conclude: “Our results show that significant improvement in patient outcomes were achieved following QI efforts that did not rely on new medications or therapies, rather through initiating novel care processes and standardization of care.”

I think this conclusion is misleading.  First of all, as the authors point out, they did change their therapeutic approach.  They started vitamin D in more patients, used anti-TNFα therapy in more patients, and increased dosing of 5-ASA agents.  Other gains in remission rate could have been related to improved followup of patients who were doing well.

Despite my skepticism about the conclusion, I think the overall achievements are laudable.  Decreasing variation of care and assuring that all patients receive the best care possible with our diagnostic tests and current therapies is certainly worthwhile.  When patient care is studied carefully, this makes sure that “standard” practice like checking TPMT status before thiopurine use, checking PPDs before anti-TNFα therapy, and using optimal drug dosing occur in virtually all patients.

Developing a checklist for each patient can help assure that best practices occur.  For those with electronic medical records, this may mean putting in more “hard stops.”  A hard stop means the physician cannot sign out of a chart without paying attention to a specific detail.  For example, if a physician orders methotrexate, a “hard stop” could come up if the dosing was not in the typical target range.

Useful link:

Link for disease classification (quiescent, mild, moderate, severe):

http://links.lww.com/MPG/A129

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Another option for line locks

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A pediatric study from London with 19 patients demonstrates the utility of taurolidine line locks (JPGN 2012; 55: 403-7).

Taurolidine has broad antimicrobial activity against Gram-positive and Gram-negative bacteria in addition to antifungal properties.  Also, taurolidine prevents biofilm formation which can help minimize colonization of catheters.  It acts by binding to the cell walls of organisms; this results in the prevention of bacterial adhesion to biological surfaces. TauroLock™ | TauroLock™

15 of the 19 patients had a history of recurrent central catheter infections and 4 were started on the line locks empirically.  At the completion of the parenteral nutrition, 0.7 to 1 mL of the taurolidine solution was instilled and left for at least 12 hours.

Taurolidine-treated patients had 1.1 episodes per 100 catheter days of CVL infections; this compared with a rate of 8.6 episodes per 1000 catheter days for heparin control.  Furthermore, 74% (14) had no infections for up to 33 months after changing to taurolidine.  No reports of mulitresistant organisms or adverse effects were reported.  Taurolidine is nontoxic for humans and rapidly metabolized to taurine, carbon dioxide, and water.

To my knowledge, taurolidine is not available in the U.S.  Nevertheless, the data on line locks indicate that antimicrobial line locks are associated with reductions in catheter infections.

Related blog entries:

Additional reference:

Best strategy for dose escalation of infliximab

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At least 50% of patients with long-term infliximab therapy require dose escalation.  However, dose escalation can mean doubling the dose or shortening the infusion interval.  So which strategy is best?  A recent article provides some insight into this question (Inflamm Bowel Dis 2012; 18: 2026-33).

In this multicenter retrospective study of 168 Crohn’s disease (CD) patients, the outcome of patients who had dose-doubling (n=112) to 10 mg/kg/dose/8 weeks was compared with patients whose infusion intervals were halved to 5 mg/kg/dose/4 weeks (n=56).  The entire cohort had a mean age of 25 years and a mean disease duration of 12 years.  39% had a history of previous intestinal surgery.  Concurrent use of thiopurines was noted in 68% and concurrent use of methotrexate in 4%.

Sustained response at 1 year to dose-doubling strategy was 50% compared with 39% in the interval-halving group.  Favorable factors included nonsmoking status, normal C-reactive protein, and CD diagnosis between 16-40 years of age.

It is noted that a subsequent dose escalation was experienced by 28 of the 87 patients who had loss of response after first dose escalation.  Regained response occurred in 9 (32%) of this cohort.

The authors indicate that increasing the dose to 10 mg/kg/8 weeks is likely preferable due to convenience and cost.  At the same time, it is apparent that shortening the infusion interval is not likely to be more effective than dose doubling.

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Does bone density improve with IBD therapy?

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Long term followup is needed to determine the significance of low bone mineral density (BMD) in children and adolescence with IBD; data with 2 year followup is available (JPGN 2012; 55: 511-18).

In this study from Sweden, 144 patients with IBD were enrolled and 126 were available at 2-year followup (2003-2005).  Among the 144 patients, there were 93 males and 83 with UC. Low BMD was noted in children with both UC and CD for the lumbar spine at baseline and no improvement was noted at 2 years.  Only boys had lower BMD z scores for the lumbar spine (LS) (-1.1); girls had normal LS z scores (0).

While the investigators could not demonstrate catch up in bone mineral density, they note that gains in BMD may accrue beyond late adolescence into early adulthood; this takes place after completion of linear growth.  In the subgroup of subjects in early adulthood, there was improvement in BMD:

  • For boys: from -1.7 at baseline (age 17.9) to -0.5 at followup (age 20.0)
  • For girls: from -0.4 at baseline (age 17.1) to 0.4 at followup (age 19.2)

With greater use of biologic therapy, these data are likely to change.  Among medical treatments, only biologic therapies have been shown to improve bone formation and improve catchup growth.

Related blog entry:

Additional references:

  • -JPGN 2011;53: 361. Similar prevalence of low Vitamin D as general population –58% with less than 32.
  • -JPGN 2011; 53: 11. Guidelines for low bone mineral density in IBD.
  • -JPGN 2009; 48: 538. Need to adjust bone density for bone age.
  • -Gastroenterol 2009; 136: 123. Longitudinal bone health study. Steroids did NOT adversely affect bones. n=78.
  • -Clin Gastro & Hep 2008; 6: 1378. IFX improves biomarkers of bone formation.
  • -J Pediatr 2008; 153: 454, 484. Use of biomarkers of bone turnover in Crohn dz; even when controlling for other factors like delayed bone age, delayed puberty, etc, still evidence of decrease bone formation and increased resorption.
  • -JPGN 2007; 45: 538. Ca/Vit D supplements -no change in BMD in IBD patients over 12 months.
  • -Clin Gastro & Hep 2007; 5: 721. DXA may not predict risk well.
  • -IBD 2007; 4: 416. Inflammation, not steroids, is key factor in bone mineral density.
  • -IBD 2006; 13: 42. Natural hx of bone mineral density in IBD; steroid dose did not correlate with BMD. Children did not have “catch up” bone density.
  • -JPGN 2006; 43: 597. Crohn’s patients had similar rate of fractures as siblings w/o IBD.
  • -Clin Gastro & Hep 2006; 4: 152. Osteoporosis in IBD.
  • -IBD 2006; 12: 797. Review of bone mineral density with IBD
  • -Clin Gastro & Hepatol 2005; 3: 113-121, 122-132 & editorial 110. In 1st article, budesonide better for bones than other steroids. In 2nd article, unable to show benefit of addition of etidronate to Ca++/Vit D.
  • -NEJM 2002; 351: 868. Intermittent steroids in nephrotic syndrome did NOT change bone mineral density.
  • -Gastro 2001; 121: 1485-88. Tanning bed Rx of vitamin D deficiency.
  • -Gastro 2000; 119: 639-46. Alendronate increases BMD in pts c Crohn’s
  • -NEJM 1998; 339: 292-9/ J Bone Miner Res 2000; 15: 1006-13. Bisphosphonates effective in steroid-induced bone disease

False-positive serology for Celiac disease

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It is prudent to exercise caution in establishing a diagnosis of Celiac disease (CD) in young asymptomatic children who are identified with screening serology (J Pediatr 2012; 161: 980-14).

In this Italian study, a nationwide, multicenter, prospective intervention trial was established to assess the role of age at gluten introduction on development of CD.  Subjects were recruited at birth who were at increased risk for CD; they had at least one first-degree relative with CD.

In their cohort, 96 children were identified.  In addition to having an affected first-degree relative, all children had positive serology (21 with positive tissue transglutaminase IgA antibody [tTG] and 1 with IgA deficiency/positive gliadin IgG antibody) and results of a small intestinal antibody.

While 72 had definitive CD, 24 were considered potential CD (serology positive/Marsh 0-1 histology) and asymptomatic.  The fascinating part of this study was the followup of the potential CD cases –21/24 continued on a regular diet.  Only 1 developed overt CD. 18 (86%) developed normal serology and 2/21 had fluctuating antibody levels after two years.

Based on their findings as well as consensus guidelines, the authors propose that asymptomatic young patients with abnormal serology should be followed for at least 3-6 months as long as tTG < 11 times ULN.

Other findings:

  1. Breastfeeding may have a protective role; individuals with overt CD had a shorter mean duration of breastfeeding than the potential CD group (4.2 months compared with 5.1 months).
  2. Gluten introduction at age 6 months did not increase risk of overt CD (compared to potential CD) relative to introduction at 12 months.

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How to dissolve a bezoar

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Some bezoars, like lactobezoars, can resolve quite easily often with intravenous fluids.  Trichobezoars often require surgery.  Phytobezoars can dissolve with  diet coke and cellulase (Gastroenterol Hepatol 2012; 8: 770-72).

A phytobezoar, which is the most common type, is composed of indigestible fruit and vegetable fibers and occur in the setting of impaired gastric motility.  In the three cases presented, the combination of diet coke and an over-the-counter cellulase (Enzymedica Digest Gold) which contains 3000 units of cellulase per capsule was successful at dissolution of the phytobezoars over a 6-8 week period.

The role of the diet coke is less certain.  The sodium bicarbonate in sodas and the penetration of carbon dioxide bubbles may have facilitated dissolution.  Additionally, the acidic pH (2.6) of Coca-Cola along with the phosphoric and carbonic acids may have been beneficial.  While Coca-Cola and Diet Coke have the same potential mechanism of action, Diet Coke is easier to administer in diabetic patients.

Additional references: