Study finds sharp increase in BMP use for spinal fusion surgery

The use of bone morphogenetic protein (BMP) for spinal fusion surgery has risen sharply over the past decade, increasing costs with no evidence of improved outcomes, reports study in the February 1 issue of Spine. The journal is published by Lippincott Williams & Wilkins, a part of Wolters Kluwer Health.

"[The] results suggest that BMP may add substantial cost to fusion procedures, with little improvement in subsequent reoperation rates," according to the new research, led by Dr Richard A. Deyo of Oregon Health and Science University, Portland.

BMP Now Used in Nearly 30 Percent of Spinal Fusion Cases
Using Medicare data from 2002 to 2008, the researchers analyzed trends in the use of BMP for spinal fusion surgery in older adults with one specific diagnosis: lumbar stenosis (narrowing of the spinal canal in the lower back). Approved by the U.S. Food and Drug Administration in 2002, BMP is a growth factor that can induce the formation of new bone. It provides an alternative to using the patient's own bone—typically obtained from the hip bone (iliac crest)—as a source of graft material.

On analysis of nearly 17,000 spinal fusion procedures, the use of BMP increased rapidly: from 5.5 percent of procedures in 2003 to 28.1 percent in 2008. BMP was more likely to be used in patients with previous surgery or those undergoing more complex spinal fusion procedures. The results supported the safety of BMP, showing no increase in major medical complications.

However, the use of BMP did not reduce the need for repeat surgery. In both groups, about three percent of patients underwent repeat surgery within one year, and six percent at two years. Repeat surgery rates were also similar for patients undergoing more complex spinal fusion procedures with and without BMP.

Spinal fusion procedures using BMP were considerably more expensive, with an average increase of $15,000 in hospital charges. However, under Medicare's Diagnosis-Related Group system, actual reimbursements were substantially lower: average difference $850.

Increased Costs, but No Apparent Improvement in Results
The rapid growth of BMP without increased complications suggests that this bone growth factor can safely be used as an alternative to the patient's own bone. However, spinal fusion procedures using BMP cost more, with no reduction in the need for repeat surgery. Patients receiving BMP were less likely to need nursing home care while recovering after surgery, which may at least partially offset the added costs.

Previous small studies reported higher rates of "solid fusion" in patients undergoing spinal fusion surgery with BMP, compared to bone grafts alone. The new study is one of the first to look at how BMP affects the outcomes of spinal fusion for patients in routine care—who often differ from those enrolled in formal clinical trials.

The results show that use of BMP for spinal fusion surgery increased rapidly after its introduction in 2002, particularly for more complex cases. The use of BMP appears safe, with no increase in complication rates. However, reoperation rates are nearly identical, even after adjusting for patient and surgical characteristics.

The authors acknowledge their study has some important limitations—including a lack of information on key outcomes such as pain and functioning. Dr Deyo and coauthors conclude, "Our findings suggest the value of studying effectiveness in routine care to complement evidence from randomized efficacy trials [and] the importance of studying the effectiveness of new technology in the full range of patient demographics and indications in which it may be used."