Research Shows BMP Use in Pediatric Fusion Does Not Improve Revision Rates

Jeffrey C. Wang, MD comments

In the first study to provide 10-year utilization and outcome data for bone morphogenetic protein (BMP) use in pediatric patients who underwent spinal arthrodesis, researchers found that BMP does not improve revision rates and should be used with caution. The findings, which will be featured in the Journal of Pediatric Orthopaedics, were published ahead of print in January 2017.

BMP is not approved by the U.S. Food and Drug Administration (FDA) for use in pediatric spinal arthrodesis, and when BMP is utilized in pediatric spinal surgery, it’s use is off-label. Despite this, studies have shown that BMP is used in up to 17 percent of pediatric spinal fusions. 
Young girl hugging a teddy bearOf 7,312 children and adolescents who had spinal fusion during the study period, 462—or 6.7 percent—received BMP.The study notes that use of BMP has increased in fusion augmentation. But children aren’t at as great of risk of failed fusion as adults. As such, the need to augment with BMP is questionable.

“Use of BMP in pediatric patients is controversial,” wrote the study authors. “Although in adult spine arthrodesis, the nonunion rate is as high as 10% to 15%, in children, nonunion after spinal arthrodesis is a much less common complication.”

Study Methods and Results
Researchers used a large statewide database maintained by the New York State Department of Health to identify pediatric spinal arthrodesis procedures in New York State from 2004 to 2014.

Of 7,312 children and adolescents who had spinal fusion during the study period, 462—or 6.7 percent—received BMP.

From 2004-2007, BMP utilization rates in pediatric cases were at 5.3 percent. But, from 2008-2010, researchers discovered a spike in utilization, as BMP was used in 8.6 percent of pediatric fusion cases. Utilization returned to pre-2008 levels from 2011-2014, when the rates fell to 5.5 percent.

The study authors also found a racial and socioeconomic connection to BMP usage. BMP was more likely to be used in pediatric patients who were older, white, and had higher family income.

Researchers found no difference in revision rates in patients who had BMP versus those who did not, though BMP was associated with a significantly higher risk for hardware complication at 5 years (BMP 7.91 percent versus non-BMP at 4.38 percent).

Pediatric BMP Use in New York Driven by a Few Surgeons
Since the introduction of BMP, it has been increasingly used to support fusion during spinal arthrodesis, primarily in adult cases. While this study also found an uptick in BMP utilization in children, the authors suggest a downward trend in BMP’s use for young patients, driven by safety concerns over off-label use of BMP for pediatric patients.

Despite industry-wide questions over BMP’s use in pediatric spine surgery—and a decline in pediatric BMP’s use by most surgeons in New York State—the study authors identified a small number of surgeons using BMP in children at a high rate.

“The continued use of BMP in New York State, despite an overall decline appears to be significantly influenced by a few providers who represent the majority of the state’s BMP use,” wrote the study’s authors.

The study authors used the statewide database to view surgeon utilization, which revealed a small number of surgeons representing more than 50 percent of the pediatric BMP use in New York State.

“This suggests a lack of standardization in practice, and highlights need for practice guidelines with regard to utilization of BMP in pediatric spinal arthrodesis,” they continued.

BMP Remains Controversial for Young Spine Surgery Patients
Though BMP’s use in adult surgery is established, larger and longer-term research is needed to better understand BMP’s effect in pediatric patients.

“Given the known low incidence of spinal nonunion in children, our observed lack of revision benefit and the associated costs of BMP use, utilization of BMP for pediatric spinal arthrodesis surgery remains controversial and should be used judiciously,” the study’s authors concluded.

Commentary
Jeffrey C. Wang, MD
Chief, Orthopaedic Spine Service
Co-Director, USC Spine Center
Professor of Orthopaedic Surgery and Neurosurgery
USC Spine Center
Los Angeles, CA

This is a large database study, which has certain benefits and limitations. The advantage of these types of studies is the huge numbers of patients and potential data contained in the database, so trends and differences found between comparative groups likely have great power to demonstrate a real substantial effect. Simple conclusions from this study can be substantial.

The disadvantage of these types of studies is the lack of specific information and outcomes data on each specific patient. They are very de-personalized, and can really only describe trends or general conclusions.

This particular study presents the usage of rhBMP in the state of New York during the study period. It is a very nice presentation of the trends of usage in the pediatric population, and the results confirm the trends of usage one might predict. The fact that this shows the trends is valuable in confirming the popular thought process in the judicious usage of this protein for spinal fusion.

The demographics are quite interesting for the groups where it is most likely to be used, and this may beg further study as to why these demographics are associated with usage. The finding that revision surgery and/or complications are similar between the groups may support the notion that the potential complications with the use of the protein are small; although they can occur, these risks overall are not higher in a large population when the protein is used.

This study indicates that these trends for New York State may be applicable to other states or the United States in general. Further study is warranted to see if there really are more complications, over a larger population, when the protein is used. Most of the studies on complications are generated from small case series or even comparative studies with a few hundred per group. These database studies can look at thousands of patients and may be more reflective of true trends and/or differences. This is a very controversial topic, so further study on the potential complications is warranted.

Updated on: 02/08/18
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