Large study notes risks of postoperative infection following spine surgery

SAN FRANCISCO—A review of more than 108,000 cases of spine surgery from the Scoliosis Research Society database has shown an overall infection rate of 2.0%, which may provide evidence against these occurrences as being labeled “never events,” according to a spine surgeon member of the organization.

“Despite the best of care, all surgical procedures have the inherent risk of complications,” Justin Smith, MD, PhD, said. “Knowing these complication rates is important for a number of reasons including patient counseling, quality improvements and potential medicolegal issues.”

Smith presented data from the Scoliosis Research Society (SRS) database to the 24th Annual Meeting of the North American Spine Society. The SRS data were collected from its members through the efforts of the organization’s Morbidity and Mortality Committee. The data were collected prospectively from multiple centers and retrospectively reviewed for this report.

Broken down by infection type, the overall superficial infection rate was 0.8% and the overall deep wound infection rate was 1.2%.

Smith noted that there are few studies in the literature that have documented infection-related complications of spinal surgery procedures and most of them are based on either small series or the anecdotal experiences of single surgeons or institutions.

The authors of the report aimed to assess the rates of wound infections based on this large series of patients and to compare these rates of infection with diagnosis and surgical parameters, he said.

“We queried the SRS data for the years 2004 to 2007 for all reports of superficial and deep wound infections and we stratified and calculated the incidence of infection based on a number of parameters, including patient diagnosis, age and the number of surgical factors as well,” Smith said.

Of the 108,000 cases reported by primary diagnosis, the distribution included: degenerative problems (44%), scoliosis (24%), spondylolisthesis (11%), fractures (6%) and kyphosis (3%).

Smith said the data revealed that based on primary diagnosis rates of infection for adult patients varied from 1.4% for degenerative disease to 4.2% for kyphosis, with scoliosis, spondylolisthesis and fractures having intermediate rates of infection.

“For pediatric patients the rates of infection ranged from 2.2% for fracture up to 5.4% for kyphosis,” Smith said. “Infection rates for scoliosis and spondylolisthesis had intermediate rates of infection.”

Cases that included a fusion had higher infection rates than cases that did not, he said. “Anterior-only fusions had a 0.6% infection rate, whereas anterior and posterior combined or posterior alone had a five times higher rate of infections—3%.”

Cases that involved an implant or those done as revisions also had higher infection rates.

Overall, minimally invasive surgical approaches had about one-fifth of the infection rate compared to those not performed minimally invasively, he reported. “But it is believed that this overall comparison may be more reflective of differences in case complexities.” Specific comparisons of minimally invasive lumbar microdiscectomy and transforaminal lumbar interbody fusion (TLIF) with their respective traditional open approaches did demonstrate the minimally invasive approaches to have significantly lower infection rates.

The authors reported in the study abstract that the Centers for Medicare & Medicaid has created a list of “never events” and has proposed nonpayment for their treatment. “While some of these are preventable, including wrong-site surgery, wound infection following spine surgery, which is also listed as a ‘never event,’ is multifactorial and occurs despite meticulous efforts,” they wrote.

For more information:
Justin Smith, MD, PhD, can be reached at University of Virginia Health System, Department of Neurosurgery, PO Box 800212, Charlottesville, VA 22908; 434-924-2203; e-mail: jss7f@virginia.edu. He is a consultant for Axial Biotech, and receives speaking and/or teaching arrangements from Medtronic and Biomet.
Reference:
Smith J, Shaffrey C, Sansur, C. et al. Rates of infection following spine surgery based on 108,419 procedures: A report form the Scoliosis Research Society Morbidity and Mortality Committee. Paper #138. Presented at the 24th Annual Meeting of the North American Spine Society. Nov. 10-14, 2009. San Francisco.