Marked Rise in Lumbar Fusion Rates Found in Past Decade

Highlight From the 33rd Annual Meeting of the North American Spine Society (NASS 2018)

Peer Reviewed

The rate of lumbar fusion performed in the United States increased by 32% between 2004 and 2015, with the largest increase (73%) found among patients aged 65 years and older, Brook I. Martin, PhD, MPH, told attendees at NASS 2018 held September 26-29 in Los Angeles, CA. Findings from this study were recently published online ahead of print in Spine.
X-ray film highlighting lateral view of the lumbo - sacral spine. Photo Credit: herniation, spinal degeneration and stenosis accounted for approximately 43% of the total volume of elective lumbar fusions in 2015. Photo Credit:
Lumbar fusion is a frequent target for coverage and reimbursement policies intended at directing the efficient use of healthcare resources, explained Dr. Martin, who is Research Associate Professor of Orthopaedics and Adjunct Associate Professor in Population Health Sciences at the University of Utah School of Medicine in Salt Lake City. Use of lumbar fusion in the treatment of primary disc herniation, degenerative disc disease, and spinal stenosis without instability is controversial, he said. In contrast, greater evidence of efficacy for lumbar fusion has been found in the treatment of spinal deformities, spondylolisthesis, and scoliosis.

To better understand recent trends in lumbar fusion rates and associated costs by surgical indication, the researchers used data from the National Inpatient Sample for the years 2004-2015 to identify adults (>20 years of age) who underwent elective lumbar fusion. The registry included 100% of discharges from approximately 20% of hospitals in the United States. The complex sampling strategy is used to generate an unbiased national estimate of procedures and costs, Dr. Martin told NASS 2018 attendees.

The researchers used a validated algorithm based on ICD-9/10 codes to classify the indications for spine procedures, and applied Healthcare Cost and Utilization Project cost-to-charge ratios to calculate hospital costs adjusted for inflation. The hospital costs exclude professional fees and noncovered services, Dr. Martin told NASS 2018 attendees.

The following exclusion criteria were used: nonelective admissions, cancer, vertebral fracture and dislocation, spinal cord injury, congenital anomaly, inflammatory spondylopathy, trauma, drug abuse, HIV, spine abscess, osteomyelitis, and pregnancy.

Trends in lumbar fusion procedure rates and volume, as well as associated hospital costs, were analyzed using a Poisson regression adjusted for patient characteristics.

More Than 2 Million Lumbar Fusions Were Performed in 2015

For all age groups, the rate of lumbar fusion surgeries increased by 32% (from 60.4 to 79.8 per 100,000 adults) between 2004 and 2015 from 122,679 in 2004 to 199,140 million in 2015. Among patients age 65 years and older, the lumbar fusion rate increased by 73% (from 98.3 to 170.3 per 100,000 adults) and the volume increased by 138%.

A slight increase in the mean age of the population was found along with a decrease in the length of stay as comorbidities increased, probably due to the increasing age of the patient population, Dr. Martin said.

Further analysis by surgical indication indicated that the largest increases in rate of lumbar fusion were performed to treat spondylolisthesis (+47,390 operations, 111%) and scoliosis (+16,129 operations, 187%). The high rate of lumbar fusion performed for spondylolisthesis may reflect the aging population, a lower threshold to operate in older patients, and possible changes in coding practice over time, Dr. Martin explained.

While the rate of fusion for disc herniation and disc degeneration declined in recent years, disc herniation/degeneration and stenosis still accounted for approximately 43% of the total volume of elective lumbar fusions in 2015 compared with 58% in 2004, Dr. Martin said. The decline in lumbar fusion rates for disc degeneration and herniation is “likely prompted by payer’s scrutiny of these procedures,” Dr. Martin noted.

Total inpatient hospital costs for elective lumbar fusion increased by 177% during the study period, from $3.7 billion in 2014 to $10.2 million in 2015. Mean adjusted cost per case (excluding professional fees) increased 70%, from $30,485 to $50,000 per admission in 2004 and 2015, respectively. Lumbar fusions for the treatment of disc herniation/degeneration and spinal stenosis totaled $4.0 billion in 2015, and accounted for 39% of the total cost of elective lumbar spinal fusion that year.

Study Limitations

“A few limitations of working in claims data are that ICD-9 diagnosis and procedure codes lack clinical detail and there is no ability to collect patient reported outcomes from these patients,” Dr. Martin said. Thus, data on rates of readmissions or repeat surgeries were not available for this cohort, and the cost data does not include professional fees or post-acute care costs, he added.

Dr. Martin disclosed the following relationships: Consulting: Washington State Department of Health; Research Support: University of Utah; Grants: University of Utah; Other Office: Statix.

Updated on: 09/03/19
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Brook I. Martin, PhD, MPH
Research Associate Professor of Orthopaedics
Adjunct Associate Professor in Population Health Sciences
University of Utah School of Medicine
Salt Lake City. UT

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