Use of BMP in Spinal Fusion Surgery Linked to More Complications, Higher Costs

Susan Jeffrey

July 01, 2009

July 1, 2009 — A new study shows that use of bone-morphogenetic protein (BMP) to promote bone growth in spinal-fusion surgery is associated with a higher rate of complications and higher hospital costs than surgeries where it is not used.

The researchers, led by Kevin S. Cahill, MD, PhD, from the department of neurosurgery at Brigham and Women's Hospital, in Boston, Massachusetts, conclude that their report "highlights the robust nationwide application of BMP in spinal-fusion procedures in the first 5 years of clinical usage since [Food and Drug Administration] FDA approval.

"The effects on complication occurrence in anterior cervical fusions, as well as the increases in length of stay and hospital charges, illustrate the need to continue to develop refined guidelines for usage and to further study the long-term risks and benefits of usage," they write.

Their findings are published in the July 1 issue of the Journal of the American Medical Association.

Rapidly Evolving Treatment

Back pain is a leading cause of disability in the United States, the researchers write, second only to the common cold as the most common reason for seeking evaluation by a physician. Nonsurgical approaches are the first line of treatment, but many patients will eventually go on to receive surgical intervention. "Spinal arthrodesis [fusion] as a treatment for back pain has rapidly evolved with the development of advanced spinal instrumentation and biologics to promote bony fusion," Dr. Cahill and colleagues write.

Use of recombinant BMP was approved by the FDA in 2002 to promote bone fusion in surgeries in the anterior lumbar spine. In this analysis, the authors performed a retrospective cohort study of 328,468 of these procedures carried out between 2002 and 2006 identified from the Nationwide Inpatient Sample database, a 20% sample of US community hospitals. They were looking specifically at the pattern of use and rates of complications and financial charges associated with use of BMP.

They found that use increased during that time period, from 0.69% of all fusion procedures in 2002 to 24.89% in 2006. It varied by patient sex, race, and primary payer, however, with increased use seen in women and Medicare patients and decreased use in nonwhite patients. They point out, though, that this latter finding should be interpreted cautiously, since many patients in the database did not have race information available.

Table 1. Use of BMP by Patient and Insurance Characteristics

Patient Group Procedures With BMP (%) Procedures Without BMP (%) Odds Ratio (95% CI)
Women 56.26 53.35 1.12 (1.09 – 1.16)
Medicare patients 29.62 27.16 1.43 (1.31 – 1.56)
Nonwhite patients 8.69 10.23 0.80 (0.75 – 0.85)

In a comparison of immediate postoperative in-hospital rates of complications for the year 2006 among patients undergoing spinal fusion by BMP use status, no differences were seen for lumbar, thoracic, or posterior cervical procedures, they report.

However, in univariate analyses and after multivariate adjustment, the use of BMP in anterior cervical fusion procedures was associated with a higher rate of overall complication occurrence, with the primary increases seen in wound-related complications and dysphagia or hoarseness.

Surgical Complication Rates With and Without Use of BMP

Complications Complications in Procedures With BMP (%) Complications in Procedures Without BMP (%) Odds Ratio (95% CI)
Complications 7.09 4.68 1.43 (1.12 – 1.70)
Wound-related complications 1.22 0.65 1.67 (1.10 – 2.53)
Dysphagia or hoarseness 4.35 2.45 1.63 (1.30 – 2.05)

BMP use was also associated with greater inpatient hospital charges across all categories of fusion, they report. "Increases between 11% and 41% of total hospital charges were reported, with the greatest percentage increase seen for anterior cervical fusion," they write.

The higher charges were probably partially related to greater implant charges for cases using BMP, they note, although other causes may also have had an impact. However, more information on long-term outcomes will be required to look at this issue, they conclude. "The decision to use BMP to increase bony-fusion rates may decrease the need for a revision fusion procedure; therefore, cost-effectiveness analyses must include longitudinal outcomes that are not possible in this analysis."

The study was supported by the Brain Science Foundation. The authors report no disclosures.

JAMA. 2009;302:58-66.

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