Impact of bone morphogenetic proteins on frequency of revision surgery, use of autograft bone, and total hospital charges in surgery for lumbar degenerative disease: review of the Nationwide Inpatient Sample from 2002 to 2008

Abstract

Background context: Bone morphogenetic proteins (BMPs) were developed with the goal of improving clinical outcomes through the promotion of bony healing and reducing morbidity from iliac crest bone graft harvest.

Purpose: To complete a population-based assessment of the impact of BMP on use of autograft, rates of operative treatment for lumbar pseudoarthrosis, and hospital charges.

Study design: Nationwide Inpatient Sample (NIS) retrospective cohort assessment of 46,452 patients from 2002 to 2008.

Patient sample: All patients who underwent lumbar arthrodesis procedures for degenerative spinal disease.

Outcome measures: Use of BMP, revision surgery status as a percentage of total procedures, and autograft harvest in lumbar fusion procedures completed for degenerative diagnoses.

Methods: Demographic and geographic/practice data, hospital charges, and length of stay of all NIS patients with thoracolumbar and lumbosacral procedure codes for degenerative spinal diagnoses were recorded. Codes for autograft harvest, use of BMP, and revision surgery were included in multivariable regression analysis.

Results: The assessment found 46,452 patients from 2002 to 2008 undergoing thoracolumbar or lumbar arthrodesis procedures for degenerative disease. Assuming a representative sample, this cohort models more than 200,000 US patients. There was steady growth in lumbar spine fusion and in the use of BMP. The use of BMP increased from 2002 to 2008 (odds ratio [OR], 1.50; 95% confidence interval [CI], 1.48-1.52). Revision procedures decreased over the study period (OR, 0.94; 95% CI, 0.91-0.96). The use of autograft decreased substantially after introduction of BMP but then returned to baseline levels; there was no net change in autograft use from 2002 to 2008. The use of BMP correlated with significant increases in hospital charges ($13,362.39; standard deviation ± 596.28, p<.00001). The use of BMP in degenerative thoracolumbar procedures potentially added more than $900 million to hospital charges from 2002 to 2008.

Conclusions: There was an overall decrease in rates of revision fusion procedures from 2002 to 2008. Introduction of BMP did not correlate with decrease in use of autograft bone harvest. Use of BMP correlated with substantial increase in hospital charges. The small decrease in revision surgeries recorded, combined with lack of significant change in autograft harvest rates, may question the financial justification for the use of BMP.

Keywords: Arthrodesis; Bone morphogenetic protein; Hospital charges; Lumbar spine surgery; Nationwide Inpatient Sample.