The antibiotic trimethoprim-sulfamethoxazole does not benefit children with Recurrent Abdominal Pain who are positive for Blastocystis hominis

Reference: Klaas Heyland, M.F., Patrick Buehr, and Christian P. Braegger, No Advantage for Antibiotic Treatment Over Placebo in Blastocystis hominis–positive Children With Recurrent Abdominal Pain.

Journal of Pediatric Gastroenterology and Nutrition, 2012. 54(5): p. 677–679.

Brief Summary: Blastocystis hominis (B. hominis) is a parasite sometimes found in the stools of healthy people and those with diarrhea which can cause abdominal pain or other gastrointestinal problems.  The main objective of this study was to determine if the antiobiotic trimethoprim-sulfamethoxazole (TMP/SMX) can be used to effectively treat children with recurrent abdominal pain (RAP) who are also positive for Blastocystis hominis.  Forty patients were recruited for the investigation and randomly assigned to either the TMP/SMX group or the placebo group.  The main outcome measure was the difference in Pain Index (PI) from initial treatment with TMP/SMX compared to 7 days later.    

Results: There was no significant reduction in PI between the treatment and placebo group.  A treatment with Metronidazole did reduce the PI index.    

Implications for Practice: Do not prescribe the the antiobiotic TMP/SMX for children with recurrent abdominal pain who are positive for Blastocystis hominis.

Discussion: Negative results are just as important as positive results, so I am glad to see that the author’s decided to move on with a publication on this.  I am further curious as to why the TMP/SMX anti-biotic did not work from a biological perspective.   There are some signaling pathway databases that could be used to look this up; this could be an interesting follow up study perhaps.  

At the end, the author’s suggested that since the antibiotic did not work, this is evidence that B. hominis has no causative role in recurrent abdominal pain (RAP).   It seems as if an observational study could easily verify this and would be interesting to follow up with.   

Since this study showed that the antibiotic TMP/SMX does not work, it would be interesting to see if the alternative drug – metronidazole – does significantly work vs. a placebo. 

Commentary on Statistics and Study Design:  Overall, the study design looked good. It was good to see that the investigators under-took a double blind study.  Also, I liked how the author’s included a table on the demographic properties of the placebo vs. the treatment group.  This is a really good idea, because it shows – from an actual visual standpoint - that potential confounding factors were balanced between the treatment and placebo groups.   I’m assuming the authors did an exhaustive search of any potential confounding factors here.    

The author’s had to exclude any patients from the investigation with a past history of a gastrointestinal or systematic disease.  When you have a potential confounding factor which could severely hinder the investigation such as these ones, excluding subjects with these criteria is probably the best possible option, because it is obviously not possible to really block on these types of confounding factors – especially if the sample size is small.

The statistical technique used was the Mann-Whittney U Test (also known as the Wilcoxan Rank Sum Test), and this is an appropriate technique to use since – with a small sample size – it may not be feasible to assume a normal distribution.    

A big thanks to our friends in Switzerland for doing this investigation!     

A prospective study to determine if Helicobacter pylori infection is strongly associated with gastric and duodenal ulcers

Reference:  Schottker, B., et al., Helicobacter pylori Infection Is Strongly Associated With Gastric and Duodenal Ulcers in a Large Prospective Study. Clin Gastroenterol Hepatol, 2012. 10(5): p. 487-493 e1.

A study out of Germany on the effect of Heliocobacter pylori Infection in patients with either gastric or duodenal ulcers. 

Brief Summary:   It is known that Heliocobacter pylori infection (a type of bacteria which infects the stomach) is a risk factor and strongly associated with peptic ulcer disease (PUD), but it is un-known if it is associated specifically with gastric and duodenal ulcers – two specific sub-types of peptic ulcer disease (PUD).  The main objective of this prospective study was to determine the degree of association between Heliocobacter pylori infection with both gastric and duodenal ulcer disease separately.  Furthermore, patients with Heliocobacter pylori infections were further delineated between those which had expression of the cytotoxin-associated gene A (cagA+) and those that did not express the gene (cagA-).  A series of demographic factors along with whether the patient had an infection of Helicobacter pylori was collected over a period of 2 to 5 years from a German population of about 10000 individuals.   The authors also conducted a cross-sectional study to identify the risk factors of lifetime history of peptic ulcer disease.  

Results: For those patients who had a cagA positive strain (cagA+) and a Helicobacter pylori infection, there was a significant association between the presence of both the gastric and duodena ulcers separately and the Heliocobacter infection.  For those patients who did not have the cagA positive strain (cagA-) and a Heliocobacter pylori infection, the association with a Heliocobacter infection was not significant.

 

Implications For Practice: Heliocobacter infection is a strong risk factor for both gastric and duodena ulcers – especially if the patient has a positive expression for the cytotoxin-associated gene (cagA+).

Discussion: Really great investigative work here – especially the study design which I will get to in a bit.  From a biological perspective, I wonder why the patients which had an expression for the cytotoxin-associated gene A also had a much higher likelihood of association than those which did not.  Obviously, since I’m not the main author and it’s hard for me to find time to divulge myself into an investigation like this, questions like this are probably straight forward for the authors (but not to me).

Also, curious   

Commentary and Statistics and Design:  aww man, where do I start?  I really like the statistical analysis and study design of this investigation.  First, the authors were correct in the statement that prospective studies are better able to detect a true causal relationship for a given observational factor than a cross-sectional study.  The reason being is that prospective studies are better able to delineate out any potential confounding factors by the means of excluding certain patients who could confound the investigation in the first place.  This is especially true with medical based studies and is the reason why prospective studies should be chosen over cross-sectional studies for the purpose of identifying risk factors of a given disease.

           Also, I liked how the authors performed both a cross-sectional and longitudanal study with essentially the same data.  Often times in the search for risk factors, the authors will only conduct a prospective study for the risk factors, but there is a-lot of other useful information that the authors could extract initially with a cross-sectional study.    

Also, I liked how the authors included both the results from the logistic regression in both the univariate and multi-variate perspective.  Often times, I see authors include results only from the univariate perspective, but it is often best to report the results of both, because it gives a reader a sense of how the associations change from non-control to a control based setting based on the other variables.   Also, the tables were made very nicely for visualization by the reader.    The authors definitely did their job in searching for any and all potential variables to include in the model – good job here. 

My only question is the following.  In the cross-sectional study, why did the authors decide to separate the categorical and continuous variables for the use of the full multi-variate model?  I couldn’t find an answer from this in the paper, but I’m sure the authors have good reason.  I see no reason why the full model could not have included both. 

A big beer at the Hofberhaus for our German friends!  This paper will definitely be one of the references I go back to when it comes to statistics and study design.

  

Gone for a long time

Sorry for being gone for some time folks.  Been really busy on my end finishing up some school-work and what-not. However, I look forward to updating this blog on a regular basis from now on for some time!

Important to Notify Patients About Adverse Effects of Colonoscopy

A great study from the Netherlands detailing the negative effects of a Colonoscopy.

Summary: The main objective was to study was the adverse effects of a Colononscopy after the procedure. The authors found that about 1 percent of the accrued patients (n=1114) had experienced a major adverse event (hospitalization) and about 30 percent (!) of the patients had experience a minor adverse event (no hospitalization) 30 days after their colononscopy.  The study showed that those patients who experienced an adverse event were found to have a more negative view of Colononscopies and consequently less likely to return for another colonoscopy in the future.

Implications for Practice: The finding that 30 percent of patients were found to have a minor adverse effect from a Colonoscopy should raise an alarm for any Gastroenterologist.  This underscores the importance of notifying patients about the potential adverse effects of a Colonoscopy and following up with them after the procedure.  Still, Colononscopies are deemed rather safe and highly recommended.      

It is interesting that females and those under the age of 50 were shown to have significantly higher chance of experiencing an adverse event compared to males and those over the age of 50 respectfully.  It is difficult to elucidate the exact reason.  Another study did show that females were more likely to experience colonic perforation compared to men.  Follow up studies on this would be compelling.

Welcome!

Welcome everybody to my GastroenterologyBlog!  I hope everyone - both doctors and patients - can find this useful for whatever your gastroenterology needs may be!  I will be updating it frequently, so I really hope that you guys all come back!