Patients Who Fit Guidelines For Lumbar Fusion More Likely To Have Positive Outcomes

Patients who received spinal fusion were more likely to report improvements in pain if they fit criteria established in the North American Spine Societies lumbar fusion guidelines, a small study suggests.

An analysis of data from 309 patients, 21 of whom did not fit the guidelines, found that those who did meet NASS criteria more often experienced meaningful improvement in disability index scores (66% versus 38%) during six months of follow-up. Accounting for factors such as age, gender, and surgical approach, researchers calculated that patients fitting the guidelines had three times greater odds (OR 3.04) of a successful outcome, according to the report published in Neurosurgery.

"The take-home from this study is that guidelines are a good thing and that by following the guidelines you usually get a good clinical outcome - and that applies to anything," said the study's lead author, Dr. James Harrop, a professor and chief of the spine and peripheral nerve surgery division at the Vickie and Jack Farber Institute for Neuroscience at Jefferson Health, in Philadelphia. "I'm not saying someone should never have the surgery if they don't meet the guidelines. Guidelines are guidelines and they are not black and white."

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To take a closer look at how important it is for patients to align with guideline criteria, Dr. Harrop and his colleagues prospectively evaluated and categorized all elective lumbar fusion cases in adults that occurred between March 2018 to August 2019 at Jefferson Health. Cases were assessed based on evidence-based medicine (EBM) guidelines for surgical indications, and deemed either EBM-concordant or EBM-discordant for lumbar fusion surgery. Assessments were done in a blinded fashion and did not influence the decision of a patient's surgical team.

Patients were asked to fill out a questionnaire, the Oswestery Disability Index (scored from zero to 50, with lower scores equal to less disability) prior to surgery, and again at two weeks, six weeks, three months, and six months. Patients also supplied demographic data at the study's outset, including age, gender, BMI, presence of diabetes, osteoporosis, smoking status, previous spine surgery, and American Society of Anesthesiologists class. The minimal clinical important difference (MCID) was defined as a reduction of five or more points in ODI score.

Specific NASS fusion criteria were placed into nine categories: unstable infection, unstable neoplasm, unstable trauma, deformity, stenosis, disc herniation, synovial cyst, discogenic pain and pseudoarthrosis. Individual surgeon and surgical approaches were recorded as: anterior, posterolateral, or interbody fusion (transforaminal, posterior, or lateral).

The researchers initially entered 325 lumbar fusion patients in the study, but in their analysis included only the 309 for whom there was follow-up data at six months. The median preoperative ODI score was 24.4 with a median six-month improvement of 7 points. Based on the ODI scores, 246 out of 309 patients (79.6%) experienced improvement, 12 patients (3.8%) remained the same, and 51 patients (16%) had worsened.

A total of 191 patients (62%) had improvement in ODI reaching MCID at six months follow-up, while 118 did not. Of the 191 patients achieving MCID in ODI, 183 (96%) were EBM concordant while among the 118 patients who did not achieve MCID in ODI, 105 (89%) were EBM concordant.

In addition, EBM discordant mean ODI improvement was only 2.14 points compared to 7.86 in the concordant patients, for a mean difference of 5.71, the researchers note.

Dr. Harrop and his colleagues found that of all the variables they examined - concordance with NASS guidelines, patient BMI, whether it was a first back surgery or a revision - guideline adherence in patient selection was most strongly associated with positive ODI outcomes.

"I applaud the authors for what they were trying to do," said Dr. Andrew Hecht, a professor of orthopedics and neurosurgery at the Icahn School of Medicine at Mount Sinai and chief of spine surgery at the Mount Sinai Health System in New York City. "This was a heterogeneous group of problems and, more important, there was a lot of revision surgery included. I think if they had eliminated the revisions and included data from other centers you would see a powerful message."

With that said, the new study is "a very good step in the direction of drawing attention to the diagnoses that have much better results," Dr. Hecht said. "This is a conversation that never gets old and will be constantly refined."

Even with the study's limitations, "there is an important message here for all spine surgeons: outcomes really are clinically dependent on indication for surgery," Dr. Hecht said. "If you're going to fuse someone there are some really good reasons to do it and some that are not nearly as good."

This is "good preliminary data," said Dr. Harvey Smith, an associate professor of orthopedic surgery and neurosurgery at the University of Pennsylvania and section chief of orthopedic spine surgery at Penn Medicine in Philadelphia. "It shows the need for broader, multicenter prospective trials. It shows that we need to improve the efficacy of figuring out who would improve."

The study will also help patients who won't do well with the surgery understand why, Dr. Smith said. "It shows the importance of using caution when you're not following the guidelines," he added.

—Linda Carroll

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