HCRN Update: Shunt Infection Risk and Treatment in Children

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Tamara_SimonBy Ashly Westrick, Research Programs Manager

This Research blog series is dedicated to highlighting the current studies of the Hydrocephalus Clinical Research Network (HCRN). The HCRN is a collaborative research network of nine pediatric children’s hospitals conducting important research on hydrocephalus. We hope you enjoy reading about the important work of the HCRN.

Our HCRN blog series continues with a discussion with Tamara Simon, MD, MSPH, an Assistant Professor of Pediatrics and a Pediatric Hospitalist at Children’s Hospital of Seattle.  She is the principal investigator for the shunt infection section of the Hydrocephalus Clinical Research Network’s (HCRN) Registry. The results of her most recent study,
“Cerebrospinal fluid shunt revisions, far more than patient factors, confer risk of shunt infection,” was presented at the Pediatric Academic Society meeting May 5th, 2013 in Washington, D.C. We talk with Dr. Simon about her research involvement with the HCRN in our continuing blog series.

Dr. Simon received a BA with honors in molecular biology from Colgate University, a MD with honors from the University of North Carolina at Chapel Hill School of Medicine and a Master’s of Science in Public Health (MSPH) from the University of Colorado at Denver. She is the proud mother of two boys: an eight year old and a six month old. She spends her spare time being a mom, spending time on the beach, hiking, and going to baseball games. She shares that it has been a great privilege to work with the HCRN, which has been an amazing place to start her research career.

HA: What has your involvement with HCRN been?

DR. SIMON: As a pediatric hospitalist, I am often caring for patients who present to the hospital for surgery but develop medical complications. Therefore, my focus is a bit different from the other principal investigators in the HCRN. When I became faculty at the University of Utah in 2006, I had the great opportunity to work with Dr. John Kestle (co-founder of the HCRN). During this time, I applied and received a career development grant award from the National Institutes of Neurological Disease and Stroke (NINDS) that permitted me to work on multi-center studies within the context of the HCRN. The grant had two components: a training component and a research component. Part of what attracted me to work with the HCRN was that it is a training ground to learn how to conduct multi-center clinical studies. For the research aspect of the award, I thought about my life as a hospitalist and where my care of patients intersected with neurosurgeons and it is often at the bedside with children with shunt infection.

HA: What do you believe to be the significance of your research? 

DR. SIMON: Shunt infection treatment is incredibly frustrating for children, families, and their medical providers. Treatment often involves two surgeries – the first surgery to remove or externalize the shunt, followed by a very long hospital stay of usually 10 to 14 days to receive intravenous antibiotics, and then a second neurosurgical procedure to replace the shunt. Even with this aggressive treatment, we still see re-infection at rates of 20 to 25%. This reinfection rate is, in my opinion, completely unacceptable and there is a great deal we don’t know about the right way to treat infection. Therefore, it wasn’t hard for me to come up with a research topic for my career development award!

HA: Can you tell us about your current research?

DR. SIMON: The reason we don’t have a lot of information about how to treat infection is because the studies conducted have been at single centers and there are not enough children treated at one center to draw really meaningful conclusions. I had the great opportunity to design the shunt infection data collection for the HCRN registry. The registry was started in 2008 and has since been implemented at all of the HCRN sites. It is an incredibly powerful tool where we are documenting the care of the patients in the network. We have been waiting to accrue a large number of children in order to analyze the infection data, and we currently have 607 children in the registry treated for infection or infection-like episodes. I am really looking forward to start to analyze the data.

One of the aims of my career development award was to look at risk factors for first infection. As I mentioned before, one problem with the shunt infection literature is that there are low numbers of children in single center studies or, in order for a center to accrue enough patients, the center will have to collect data for a very long time, during which time management of conditions may change. Therefore, a lot of prior work tended to also result in competing or different conclusions. For instance, one study might find that IVH of prematurity is a risk factor for first infection and then another study can conclude the opposite.  By using the HCRN registry, we are able to overcome these limitations – since we have the pooled data from nine centers, we have a very large number of patients who are being treated in a very contemporary fashion.

We were able to capitalize on the registry data, which currently has 1036 children, of which 112 of them developed a first infection. We’ve been able to look at risk factors for children to develop first infection. A few different factors were independently associated with first infection. A couple of protective factors included age 6 to 12 month and prior neurosurgery; and a gastrostomy tube was found to have a twofold higher hazard for infection.  However, by far the most dramatic risk factor for infection was the development of surgical malfunctions requiring revision surgery between the initial placement. We saw a 4-fold higher hazard for children who underwent one revision and a 13-fold higher hazard ratio for children who underwent two or more revisions.

What is interesting about this study is that we have always known in our clinical practice that patients with revisions were more likely to have infection but now we are able to quantify that risk and really put the underlying patient factors into perspective. It is really clear that the best way to prevent infection is to prevent revision surgery. With this study, we were also able to replicate what we found at a single center (Salt Lake City) and ensure the findings are generalizable (with 5 additional sites). Plus, the data collected for our current study is prospectively collected, whereas the data from our last study was retrospectively collected; prospective data is a stronger data source.

HA: What do you see in the future for the infection network?

DR. SIMON: The next step in our research is to look at how the infection was treated. We want to know what variations exist in their antibiotic treatment and their surgical treatment, and whether differences exist by center or patient characteristics. This will give us a better understanding of the kinds of variation of treatment that is out there. Once we have a good handle on that, we will be able to do a large study looking at whether there are differences in reinfection based on the differences in how kids are treated. For example, does a shorter course of antibiotics increase the risk of reinfection rates? This is the type of question that we really want to be able to answer to help children with hydrocephalus and their providers. We are hoping to get that work done this winter and spring.

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