Research Results Raise Important Questions About Usefulness of Bone Morphogenic Protein in Spinal Fusion Surgery


Newswise — NEW ORLEANS (April 29, 2013) — With some recent studies questioning the use of bone morphogenic protein (BMP) in spinal fusions to prevent nonunions and reduce re-operations, researchers today during the 81st American Association of Neurological Surgeons (AANS) Annual Scientific Meeting presented the latest study results on this topic. Researchers involved in the study Does Bone Morphogenic Protein Change the Operative Nonunion Rates in Spine Fusions? — which will be presented by Kern H. Guppy, MD, PhD, FAANS, from 2:40-2:48 p.m. on Monday, April 29 — reported that after studying a large cohort of spinal fusions at all spinal levels with and without BMP, they did not find any statistically significant difference in operative nonunion rates. The study co-authors are Johannes Bernbeck, MD; Jessica Harris, MS; Christopher Ake, PhD; Liz Paxton, MA; and Kim Phan, BA.

For the study, the Kaiser Permanente Spine Registry was used to identify 9,425 spinal fusion cases between 2009-2011. Patient characteristics, diagnosis, operative time, length of stay and re-operations were extracted from the registry, with re-operations for nonunions adjudicated via chart review. Cox regression models were used to evaluate the risk of re-operation for nonunions while adjusting for potential confounders.

In the study cohort, 5,456 cases used BMP and 3,969 did not. The mean age was 60.4 years (SD=12.9), with the majority being females (53 percent) and with median follow-up time of 1.2 years (IQR: 0.6-2.0) BMP and Non-BMP groups differed statistically in age, sex, ASA, operative time and length of stay. Differences in re-operation rates for non-BMP and BMP nonunions at 1 year (0.9 percent vs. 1.1 percent) and at 2 years follow-up (2.4 percent vs. 1.8 percent) were not statistically significant. After controlling for differences in patient characteristics, operative time, diagnosis group, region of spine fused (cervical only, lumbar only, other) and number of levels fused the risk of re-operation in the BMP group versus the non-BMP group was 0.64 (95 percent CI: 0.39-1.03). Differences in BMP vs. non-BMP rates did not reach statistical significance within the lumbar only or cervical only subregions.

“The study raises important questions on the usefulness of BMP in spinal fusion surgery. This is not the first study that points [these questions] out, but it is by far the largest series of patients with such detailed analysis — over 9,000,” said Kern H. Guppy, MD, PhD, FAANS. “There are several factors we should keep in mind about this study: on the one hand, it is not a prospective randomized study, so there can be selection biases in the patients who received BMP. However it uses real-world data without any of the restrictive inclusion/exclusion criteria encountered in a clinical trial. Statistically we attempted to correct for selection bias, but even with our corrections, the results do not show a statistically significant difference in nonunion rates. We expect to continue to monitor the performance of BMP closely as we accumulate more cases and follow-up time in our registry.”

Disclosure: The author reported no conflicts of interest.

Media Representatives: The 2013 AANS Annual Meeting Press Kit includes releases on highlighted scientific research, AANS officer and award winners, National Neurosurgery Awareness Week, and other relevant information about this year’s program. Those releases also will be posted under the Media area on the 2013 AANS Annual Scientific Meeting website (http://www.aans.org/Annual Meeting/2013/Main/Media.aspx). If you have interest in a topic related to neurosurgery or would like to interview a neurosurgeon — either on-site or via telephone — during this year’s event, please contact John Iwanski, AANS Director of Member and Public Outreach, via the onsite press room at (504) 670-4910 or e-mail him at jai@aans.org.

About the 2013 AANS Annual Scientific Meeting: Attended by neurosurgeons, neurosurgical residents, medical students, neuroscience nurses, clinical specialists, physician assistants, allied health professionals and other medical professionals, the AANS Annual Scientific Meeting is the largest gathering of neurosurgeons in the nation, with an emphasis on the field’s latest research and technological advances. A record-breaking 1,003 scientific abstracts were presented for review at the 2013 AANS Annual Scientific Meeting, and the scientific presentations given at this year’s event represent cutting-edge examples of the incredible developments taking place within the field of neurosurgery. Additional information about the AANS Annual Scientific Meeting and the Meeting Program can be found at http://www.aans.org/Annual Meeting/2013/Main/Home.aspx.

Founded in 1931 as the Harvey Cushing Society, the American Association of Neurological Surgeons (AANS) is a scientific and educational association with nearly 8,300 members worldwide. The AANS is dedicated to advancing the specialty of neurological surgery in order to provide the highest quality of neurosurgical care to the public. All active members of the AANS are certified by the American Board of Neurological Surgery, the Royal College of Physicians and Surgeons (Neurosurgery) of Canada or the Mexican Council of Neurological Surgery, AC. Neurological surgery is the medical specialty concerned with the prevention, diagnosis, treatment and rehabilitation of disorders that affect the entire nervous system including the spinal column, spinal cord, brain and peripheral nerves. For more information, visit www.AANS.org.

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