Epidural Steroid Injection Before Spine Surgery Linked to Postoperative Infection

Risk is present when lumbar fusion occurs within 3 months after an injection. Commentary provided by Ali A. Baaj, MD.

The timing of lumbar epidural steroid injection (LESI) treatment before spinal fusion surgery may be an important risk factor for postoperative infection. Researchers found patients who had LESI within three months of their surgery had an increased rate of postoperative infection. The findings were published online in March 2017 in the Journal of Neurosurgery: Spine.

LESIs are the most common nonsurgical treatment for lumbar stenosis and radiculopathy. The study notes that rates of transforaminal LESIs have skyrocketed 665 percent since 2000—with more than 2.2 million procedures performed each year in the Medicare population alone.
Back pain information with pills and a syringe in the backgoundResearchers found that patients who had lumbar epidural steroid injection within three months of their surgery had an increased rate of postoperative infection. While LESIs are generally considered safe, the injections may have an adverse effect on spine surgery performed shortly after infection treatment.

“Steroid injection is a known risk factor for local and/or distant infection,” write the study’s authors. “The increased risk of infection can be attributed to exogenous material introduction through the skin into the spinal epidural space, skin flora, contaminated injection material, and immunosuppressive effects of steroid agents.”

The study authors sought to understand the association between LESIs administered before surgery and infections after lumbar spinal fusion.

Study Methods and Results
The researchers used a large, nationwide insurance-based patient database for the retrospective analysis of Medicare patients 65 and older who had a one-level or two-level lumbar spinal fusion between 2005 to 2012. Using ICD-9 codes to locate the patient set, the authors identified 88,540 patients and broke them into three cohorts:

  1. Lumbar spinal fusion performed within one month after LESI (1,699 patients).
  2. Lumbar spinal fusion performed between one and three months after LESI (5,491 patients).
  3. Lumbar spinal fusion performed between three and six months after LESI (10,493 patients).

The study patients were then compared to a control group who had lumbar fusion without any previous LESI (70,857 patients).

The overall three-month infection rate after lumbar spinal fusion was 1.6 percent (1,411 of 88,540 patients). The infection risk for patients who received LESI within one month of spine surgery was the highest of all cohorts—3.9 percent (66 of 1,699). For those who had a LESI one to three months before surgery, the risk was 2.2 percent (120 of 5,491), and patients having LESI three to six months before fusion had a 1.3 percent infection rate (136 of 10,493).

The infection rate was significantly higher in patients who had LESI within one month of surgery (OR 2.6, P < 0.0001) and one to three months before surgery (OR 1.4, P = 0.0002) compared to the control group. Those who had LESI more than three months before their spinal fusion did not have a significantly higher infection risk compared to the control group (OR 0.8, P = 0.06).

Injection Timing May Be a Key Risk Factor for Infection
The findings suggest that injection timing prior to surgery may play a role in postoperative infection risk, as the risk of surgical site infection is higher if the patient received an injection less than three months before surgery. The researchers offered a hypothesis to explain why the rate of postoperative infection did not increase for patients who had LESIs more than three months after surgery. 

“It is possible that the immunosuppressive effect of a local steroid agent wears off after a specific time and thereafter does not contribute to any higher risk of infection,” write the authors.

The authors also considered that their findings may also be attributed to patients who had severe spinal pain and stenosis who don’t experience relief from LESI and then have surgery shortly thereafter.

“Severe stenosis itself can be a risk factor for longer operative times and hence a higher rate of infection,” write the authors.

Including These Findings in Patient Discussions and Considerations
As the study findings show a potential for a higher risk of infection in patients who undergo lumbar fusion surgery within three months of having LESI, the authors recommend treating physicians consider timing of treatments as part of their care plan.

“Although the overall infection rate remains low despite the use of preoperative LESIs, increasing the time interval to more than 3 months from injections to surgery may help to reduce this increased risk,” the authors conclude.

In cases where surgery is planned soon after injection treatment, the authors recommend spine surgeons discuss these findings with patients as part of the overall surgical risk factor conversation.

Commentary
Ali A. Baaj, MD
Assistant Professor of Neurological Surgery
Weill Cornell Medical College
Cornell University
New York, NY

Lumbar epidural steroid injections (LESIs) are commonly performed before spine surgery and are offered to patients who have degenerative disease of the lumbar spine. The important findings of this study suggest that spine surgeons need to be assess the timing of injections and surgery to diminish the risks of postoperative infections. 

Unless a patient is experiencing acute neurological deficits or debilitating pain, it is optimal to wait at least 12 weeks before an extensive lumbar spinal fusion procedure is performed.

I encourage patients and surgeons alike to discuss the risks of postoperative infections after lumbar spinal fusion surgery, as well to coordinate timing of injections accordingly.

Updated on: 02/08/18
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