Trends analysis of rhBMP utilization in single-level posterior lumbar fusion (PLF) in the United States

Co-delivery of rhBMP-2 and zoledronic acid using calcium sulfate/hydroxyapatite carrier as a bioactive bone substitute to enhance and accelerate spinal fusion

Recombinant human bone morphogenetic protein-2 (rhBMP-2) has been FDA-approved for lumbar fusion, but supraphysiologic initial burst release due to suboptimal carrier and late excess bone resorption caused by osteoclast activation have limited its clinical usage. One strategy to mitigate the pro-osteoclast side effect of rhBMP-2 is to give systemic bisphosphonates, but it presents challenges with systemic side effects and low local bioavailability. The aim of this in vivo study was to analyze if posterolateral spinal fusion (PLF) could be improved by utilizing a calcium sulfate/hydroxyapatite (CaS/HA) carrier co-delivering rhBMP-2 and zoledronic acid (ZA). Six groups were allocated (CaS/HA, CaS/HA + BMP-2, CaS/HA + systemic ZA, CaS/HA + local ZA, CaS/HA + BMP-2 + systemic ZA, and CaS/HA + BMP-2 + local ZA). 10-week-old male Wistar rats, were randomly assigned to undergo L4-L5 PLF with implantation of group-dependent scaffolds. At 3 and 6 weeks, the animals were euthanized for radiography, μCT, histological staining, or biomechanical testing to evaluate spinal fusion. The results demonstrated that the CaS/HA biomaterial alone or in combination with local or systemic ZA didn't support PLF. However, the delivery of rhBMP-2 significantly promoted PLF. Combining systemic ZA with BMP-2 didn't enhance spinal fusion. Notably, the co-delivery of rhBMP-2 and ZA using the CaS/HA carrier significantly enhanced and accelerated PLF, without inhibiting systemic bone turnover, and potentially reduced the dose of rhBMP-2. Together, the treatment regimen of CaS/HA biomaterial co-delivering rhBMP-2 and ZA could potentially be a safe and cost-effective off-the-shelf bioactive bone substitute to enhance spinal fusion.

A large database study of hospitalization charges and follow-up re-admissions in US lumbar fusion surgeries using a cellular bone allograft (CBA) versus recombinant human bone morphogenetic protein-2 (rhBMP-2)

Background

The objective of this study was to retrospectively compare initial procedure and 12-month follow-up hospitalization charges and resource utilization (lengths of stay; LOS) for lumbar fusion surgeries using either recombinant human bone morphogenetic protein-2 (rhBMP-2) or a cellular bone allograft comprised of viable lineage-committed bone cells (V-CBA) via a large US healthcare system database. Potentially relevant re-admissions during the follow-up period were also assessed.

Methods

A total of 16,172 patients underwent lumbar fusion surgery using V-CBA or rhBMP-2, of whom 3503 (21.66%) patients had follow-up re-admission data. Initial patient, procedure, and hospital characteristics were assessed to determine confounding factors. Multivariate regression modeling compared differences in hospitalization charges (in 2018 US dollars) and LOS (in days) between the groups, as well as incidences of potentially relevant re-admissions during the 12-month follow-up period.

Results

The adjusted mean initial procedure and 12-month follow-up hospital charges were significantly lower in the V-CBA group versus the rhBMP-2 group ($109,061 and $108,315 versus $160,191 and $130,406, respectively; P < 0.0001 for both comparisons). This disparity remained in an ad hoc comparison of charges for initial single-level treatments only (V-CBA = $103,064, rhBMP-2 = $149,620; P < 0.0001). The adjusted mean initial LOS were significantly lower in the V-CBA group (3.77 days) versus the rhBMP-2 group (3.88 days; P < 0.0001), but significantly higher for the cumulative follow-up hospitalizations in the 12-month follow-up period (7.87 versus 7.46 days, respectively; P < 0.0001). Differences in rates of follow-up re-admissions aligned with comorbidities at the initial procedure. Subsequent lumbar fusion rates were comparable, but significantly lower for V-CBA patients who had undergone single-level treatments only, in spite of V-CBA patients having significantly higher rates of initial comorbidities that could negatively impact clinical outcomes.

Conclusions

The results of this study indicate that use of V-CBA for lumbar fusion surgeries performed in the US may result in substantially lower overall hospitalization charges versus rhBMP-2, with both exhibiting similar rates of 12-month re-admissions and subsequent lumbar fusion procedures.

Trends, Costs, and Complications of Anterior Cervical Discectomy and Fusion With and Without Bone Morphogenetic Protein in the United States Medicare Population

STUDY DESIGN

Retrospective database review.

OBJECTIVES

After the Food and Drug Administration approved bone morphogenetic protein-2 (BMP) in 2002, BMP was used off-label in the cervical spine to increase bone growth and bony fusion. Since then, concerns have been raised regarding complication rates and safety. This study was conducted to examine the use of BMP in anterior cervical discectomy and fusion (ACDF) in the Medicare population and to determine risk of complications and associated costs within 90 days of surgery.

METHODS

Patients who underwent ACDF were identified using Current Procedural Terminology (CPT) and International Classification of Diseases, Ninth Revision Procedure codes (ICD9-P). Complications were identified using ICD9 diagnostic codes. Charges were calculated as amount billed, and reimbursements were calculated as amounts paid by Medicare. Data for these analyses came from a nationwide claims database.

RESULTS

A total of 215 047 patients were identified who had ACDF from 2005 to 2011. For the majority of the procedures (89.0%), BMP was not used. BMP use rose from 11.84% in 2005 to a peak of 16.73% in 2007 before decreasing to 12.01% in 2011. BMP was used 16% more in women than men. BMP use was the highest in the West (13.6%) followed by Midwest (11.8%), South (10.6%), and Northeast (7.5%). There was a higher overall complication rate in the BMP group (2.1%) compared with the non-BMP group (1.9%) (odds ratio [OR] = 1.11, 95% CI = 1.01-1.22). The BMP group also had a higher rate of wound complications (0.98% vs 0.76%, OR = 1.29, 95% CI = 1.12-1.48). In this study population, there was no difference in dysphagia/hoarseness, neurologic, medical, or other complications. During the 90-day perioperative period, BMP surgeries were charged at 17.6% higher than non-BMP surgeries.

CONCLUSIONS

The use of BMP in ACDF in the Medicare population has decreased since a peak in 2007. The rate of wound and overall complications for BMP use with ACDF was higher than without. Our results regarding dysphagia/hoarseness did not show a statistically meaningful difference, which is in contrast with many other studies. Charges associated with BMP use were higher during the 90-day perioperative period.

Trends Analysis of rhBMP Utilization in Single-Level Posterior Lumbar Interbody Fusion in the United States

STUDY DESIGN

Retrospective study.

OBJECTIVES

Recombinant human bone morphogenetic protein-2 (rhBMP-2) has been widely used in spinal fusion surgery, but there is little information on rhBMP-2 utilization in single-level posterior lumbar interbody fusion (PLIF). The purpose of our study was to evaluate the trends and demographics of rhBMP-2 utilization in single-level PLIF.

METHODS

Patients who underwent single-level PLIF from 2005 to 2011 were identified by searching ICD-9 diagnosis and procedure codes in the PearlDiver Patient Records Database, a national database of orthopedic insurance records. The year of procedure, age, gender, and region of the United States were recorded for each patient. Results were reported for each variable as the incidence of procedures identified per 100 000 patients searched in the database.

RESULTS

A total of 2735 patients had single-level PLIF. The average rate of single-level PLIF with rhBMP-2 maintained at a relatively stable level (28% to 31%) from 2005 to 2009, but decreased in 2010 (9.9%) and 2011 (11.8%). The overall incidence of single-level PLIF without rhBMP-2 (0.68 cases per 100 000 patients) was statistically higher (P < .01) compared to single-level PLIF with rhBMP-2 (0.21 cases per 100 000 patients). The average rate of single-level PLIF with rhBMP-2 utilization was the highest in West (30.1%), followed by Midwest (26.9%), South (20.5%), and Northeast (17.8%). The highest incidence of single-level PLIF with rhBMP-2 was observed in the age group <65 years (0.3 per 100 000 patients).

CONCLUSIONS

To our knowledge, this is the first study to report on the demographics associated with rhBMP-2 use in single-level PLIF. There was a 3-fold increase in the rate of PLIF without rhBMP-2 compared to PLIF with rhBMP-2, with both procedures being mainly done in patients less than 65 years of age.

Comparison of a calcium phosphate bone substitute with recombinant human bone morphogenetic protein-2: a prospective study of fusion rates, clinical outcomes and complications with 24-month follow-up

PURPOSE

Recombinant human bone morphogenetic protein-2 (rhBMP-2) generally provides high rates of clinical improvement and fusion. However, rhBMP-2 has been associated with adverse effects. Recently, a beta tricalcium phosphate (β-TCP) bone substitute has been developed. The aim of this study was to determine the fusion rates and clinical outcomes of patients treated with β-TCP compared to rhBMP-2.

METHODS

One hundred and thirty-five consecutive patients who underwent lateral lumbar interbody fusion with β-TCP (n = 25) or rhBMP-2 (n = 110) in the interbody cage were included in the study. The 25 β-TCP patients were a group of consecutive patients from numbers 46 to 70. Clinical outcomes included back and leg pain, Oswestry Disability Index (ODI), and SF-36 physical and mental component scores (PCS and MCS). CT scans were performed at 6, 12, 18, and 24 months until confirmation of solid interbody fusion, with no further scans performed once fusion was achieved. Targeted CT at the operative level(s) was performed to reduce radiation exposure.

RESULTS

At 24 months there was no significant difference between clinical outcomes of the β-TCP or rhBMP-2 patients, with improvements in back pain (46% and 49%; P = 0.98), leg pain (31 and 52%; P = 0.14), ODI (38 and 41%; P = 0.81), SF-36 PCS (37 and 38%; P = 0.87), and SF-36 MCS (8 and 8%; P = 0.93). The fusion rate was significantly higher for rhBMP-2 with 96% compared to 80% for β-TCP (P = 0.01). Separating patients into those with a standalone cage and those with supplemental posterior instrumentation, there was no significant difference between instrumented fusion rates of the β-TCP and rhBMP-2 patients at 6 (P = 0.44), 12 (P = 0.49), 18 (P = 0.31) or 24 (P = 0.14) months. For standalone patients there was a significant difference at 6 (P = 0.01), 12 (P = 0.008) and 18 months (P = 0.004) with higher fusion rates in the rhBMP-2 group; however, by 24 months this was not significant (P = 0.18).

CONCLUSIONS

Comparable clinical outcomes and complication rates suggest that β-TCP is a viable alternative to rhBMP-2. The difference in fusion rates for the standalone patients suggests that β-TCP may require supplemental posterior instrumentation to enhance fusion.

Meta-analysis of the Impact of Patient Characteristics on Estimates of Effectiveness and Harms of Recombinant Human Bone Morphogenetic Protein-2 in Lumbar Spinal Fusion

STUDY DESIGN

Meta-analysis of individual patient data from randomized controlled trials of recombinant human bone morphogenetic protein-2 (rhBMP-2) in lumbar spinal fusion.

OBJECTIVE

To determine how patient characteristics impact estimates of effectiveness and harms of rhBMP-2 versus iliac crest bone graft (ICBG) in lumbar spinal fusion.

SUMMARY OF BACKGROUND DATA

Patient characteristics are thought to impact rates of fusion in spinal fusion surgery, but no analyses examining the effect of patient characteristics on efficacy and safety of rhBMP-2 as compared with ICBG have been conducted.

METHODS

Using individual patient data obtained from the Yale Open Data Access Project, the impact of patient characteristics on the effects of rhBMP-2 on fusion, overall success, and harms were assessed using linear and generalized linear mixed effects models.

RESULTS

Ten industry-sponsored randomized controlled trials of rhBMP-2 were included in the analysis. There is preliminary support for an association between rhBMP-2 and improved outcomes for smokers (P = 0.01), individuals under the age of 60 years (P < 0.01), and patients of normal weight (P = 0.03), but not in patients who are nonsmokers, over the age of 60 years, obese or severely obese. RhBMP-2 usage was associated with decreased harms in individuals with no previous back surgeries but this was not seen in individuals with a previous back surgery (P < 0.01).

CONCLUSION

Effects of rhBMP-2 may vary according to patient characteristics. Future studies of rhBMP-2 should include planned subgroup analysis in patients over 60 years, smokers, patients that are obese and severely obese, and individuals with previous back surgeries to better identify those most likely to benefit.

LEVEL OF EVIDENCE

1.