Tuesday February 17th, 2015
The numbers reported this week by the Centers for Disease Control and Prevention do not represent the current state of outcomes for infants born with HLHS.
Last week the Centers for Disease Control and Prevention (CDC) posted information about a study that has recently been published in the Journal of Pediatrics called Differences in Survival of United States Children with Birth Defects: A Population-Based Study.
Purpose: It is important to understand what question the researchers are attempting to answer when evaluating a research study and its results. The purpose of this particular study, which was performed by a group of researchers on behalf of the National Birth Defects Prevention Network, was to evaluate possible racial or ethnic differences in survival of children born in the United States with various birth defects, ranging from congenital heart defects (CHD) to gastrointestinal defects to neurologic defects. The purpose of this study was not to describe the current state of survival in the United States for any of these birth defects.
Methods: It is also critical to understand the methods that the researchers used to answer their question. These researchers chose to use a birth defect registry that was active in several states: Arizona, Colorado, Florida, Georgia, Illinois, Massachusetts, Michigan, Nebraska, New Jersey, New York, North Carolina and Texas. In fact, some of the states had incomplete information from parts of their state. For example, births from New York City were not included in the New York state information. Importantly for HLHS, the birth defect registry captures all live births, including those infants whose parents elected comfort care only.
All studies have limitations to their methods. In the case of this study, the authors note extensive limitations in their paper. Most published studies have ~1 paragraph describing the limitations; this paper includes 4 extensive paragraphs describing the limitations. Some of these limitations include possible misclassification of birth defects and potential misclassification of deaths. It is important to note again that the purpose of this study was not to describe the current state of survival in the United States for these birth defects. If these authors wanted to answer that question, they would need to use different methods and use more current survival information.
Results and comments: This paper has some important results. The researchers found that children with birth defects born between 1999-2007 to non-Hispanic black and Hispanic mothers have a lower survival rate than those born to mothers of other ethnicities. This was especially true for children born with CHD. We do not know if this is still true in infants born with these birth defects in 2015, but this result should give us pause and cause us to look at our systems of care to make sure we eliminate any ethnic disparities in outcomes in our babies with CHD. Unfortunately, the CDC did not focus on this important finding when posting the results of this study. Instead they focused on the mortality rates of various birth defects noted in this study. In our opinion, the CDC webpage is misleading as it emphasizes the mortality rates noted in this study rather than the results of the purpose of this study, the ethnic differences in mortality rates during that time period (1999-2007). This data does not reflect current mortality rates.
What is the current state of outcomes in infants born with Hypoplastic Left Heart Syndrome? The most accurate and up-to-date information about survival for infants born with HLHS comes from the Society for Thoracic Surgeons (STS) registry, the NPC-QIC registry, and publications that look at longer term survival. The STS tracks survival until hospital discharge for all patients who undergo surgery for congenital heart disease for nearly all centers performing these surgeries in the United States.
- For the time period 2010-2013 there were 2177 Norwood procedures performed for HLHS at STS centers and there was an average survival to hospital discharge of 83% among all centers.
- For the year 2013 there were 714 Norwood procedures performed in STS centers with a 85% survival rate to discharge.
For information about survival after hospital discharge, in the “interstage” period and beyond, we need to turn to the medical literature since STS only tracks survival to hospital discharge following surgical procedures. There have been several reports describing survival after discharge following the Norwood procedure.
- The NPC-QIC registry historically has demonstrated interstage survival of ~90-92% and more recently (since January 2013), interstage survival in centers participating in the NPC-QIC collaborative is approaching 95%.
- The Pediatric Heart Network Single Ventricle Reconstruction Trial enrolled infants with single ventricle between 2005 and 2008 and looked at two different surgical approaches to the Norwood procedure. This study enrolled 549 infants (not all of them had HLHS) and the survival rate to 1 year of age was ~73%. It is important to recognize that these patients were operated on and followed at 7 Pediatric Heart Network centers and that this study was started almost 10 years ago.
The National Pediatric Cardiology Quality Improvement Collaborative remains dedicated and committed to improving not only survival but also quality of life for children with HLHS and their families. While we recognize that we have a long way to go in our efforts, we have seen tremendous improvement in outcomes in HLHS in the past decade. The numbers reported by the Centers for Disease Control and Prevention do not represent the current state of outcomes for infants born with HLHS, nor do they reflect the hard work done by caregivers and parents in improving outcomes for our patients.
Jeffrey Anderson, MD, MPH, MBA, Improvement Advisor and Research Committee Chair
Robert Beekman, MD, NPC-QIC Chair
Carole Lannon, MD, MPH, Improvement Design and Implementation Lead
Stacey Lihn, NPC-QIC Parent Lead and Sisters by Heart President
Laura E. Peterson, BSN, SM, Senior Quality Improvement Consultant