Evidence & Methods
Between 2002 and 2008, BMP was used with increasing frequency. In this paper, the authors examined the NIS to determine the impact of BMP use on other fusion-related parameters.
With the introduction of BMP use in 2002, autograft initially decreased but then returned to baseline levels. Revision fusion rates decreased slightly while hospital charges rose rapidly during this time frame. The authors suggest each of these may be BMP-related.
These results are interesting in so far as the number of revision surgeries were not dramatically impacted by the introduction of BMP, and autograft use remarkably returned to baseline levels in a short period of time. The methodology used, however, does not allow causation to be assessed. Therefore, definite conclusions about the observations noted and BMP efficacy or use cannot be confidently drawn, as this data represents Level IV evidence. Regardless, the information provided in this study should serve as a springboard for future higher quality studies.
Lumbar disc disease and other lumbar degenerative pathologies remain an important cause of disability and a common indication for nonoperative and operative therapies [1], [2], [3], [4], [5], [6], [7]. Many patients who fail nonoperative therapy may be considered for fusion procedures [4], [8]. Advances in spinal instrumentation and bone growth biologics may influence the success of fusion procedures and may impact patient outcomes. Spine surgery continues to manifest substantial growth [9], [10].
Two bone morphogenetic proteins (BMPs) were recently introduced to the US spine market. Use of BMP in lumbar spine fusion procedures, with BMP restricted to implantation with specific cages in the anterior lumbar spine, was approved by the Food and Drug Administration (FDA) [11] in 2002. INFUSE BMP (Medtronic Sofamor-Danek, Memphis, TN, USA) and OP-1 putty (Stryker Spine, Allendale, NJ, USA) are available on the US market; OP-1 is only available as a humanitarian device exemption product for revision surgery [12]. Use of BMP requires a carrier and delivery system; the delivery system may provide support for a developing fusion mass. Some insurance policy recommendations note that when BMP is used, there should be no additional coding or billing for autograft harvest [13].
Although FDA approval for use of BMP is restricted to anterior approaches to the lumbar spine combined with use of a specific lumbar intervertebral body fusion device, most use of BMP is off-label [14], [15]. The off-label use of BMP has been associated with significant complications, including obstructive airway edema in anterior cervical procedures and ectopic bone formation [15], [16].
Health policy reports have focused on regional variations in health-care spending and resource utilization. Fisher et al. [17], reporting on regional variation in Medicare expenditures, notes that physician factors must play a predominant role in variation in health-care expenditures. There is significant geographic variation in utilization of lumbar operative and nonoperative treatments [10], [18], [19], [20]. Control of health-care costs is a primary concern of present health-care policy.
Use of BMP may add significantly to total costs for spine surgery treatment. The added costs for use of BMP may be offset by higher fusion rates, decreasing the need for revision surgery, and elimination of harvest of iliac crest bone graft. Obviating the need for bone graft harvest decreases the potential morbidity associated with spine surgery by eliminating potential complications of graft harvest, including infection, hematoma, need for further surgery, and chronic pain [21], [22]. Other reports have noted that BMP may not be cost-effective in spine surgery [23].
The Nationwide Inpatient Sample (NIS) was developed as part of the Healthcare Cost and Utilization Project of the Agency for Healthcare Research and Quality and was the largest all-payer database of hospital admissions in the United States. As of 2008, NIS contains all discharge data from 1,056 hospitals located in 42 states. This sample offers a representative randomized assessment of approximately 20% of nonfederal US hospital admissions. The database has been used previously for the evaluation of spine surgery procedures and trends in utilization of health-care resources in spinal care [10], [12], [14], [24], [25], [26], [27].
We sought to assess, through the study of this administrative database, the clinical and systems impact of the introduction of BMPs on lumbar fusion patients. We analyzed the incidence of revision surgery when BMP was used, trends in the rate of autograft harvest, and overall impact on hospital charges.