Treatment effect varies significantly with individual factors

The Spine Patient Outcomes Research Trial (SPORT) had strict inclusion criteria—and that’s one of the reasons that patients improved more with surgery compared with medical-interventional treatment, according to research presented at the 2010 North American Spine Society annual meeting.

The SPORT trial compared surgical and nonsurgical outcomes for three common lumbar spine diagnoses—intervertebral disk herniation, spinal stenosis, and degenerative spondylolisthesis. This study focused on the treatment effect—the difference between surgical and nonsurgical outcomes—in patients with intervertebral disk herniation.

“The treatment effect is the difference in change scores between the surgical and nonsurgical groups,” explained Adam Pearson, MD, MS. “It compares the amount of improvement with surgery to the amount of improvement with nonsurgical treatment.”

To determine whether treatment effect varied across subgroups, Dr. Pearson and colleagues followed 1,192 patients with radiculopathy, neurologic findings, and intervertebral disk herniation confirmed with cross-sectional imaging.

In total, 788 patients with intervertebral disk herniation underwent diskectomy while 404 patients received nonsurgical treatment. The researchers used the Oswestry Disability Index (ODI) to determine the treatment effect of surgery (the difference in ODI change scores between the surgery and nonsurgery groups).

The treatment effect differed substantially among subgroups. For example, patients who had joint problems, were single, or had an unchanging symptom trend did not improve as much as patients who were without joint problems, were married, or reported that their condition was worsening.

Additionally, certain subgroups had particularly poor nonsurgical outcomes. “People with lower educational attainment, longer duration of symptoms, and possibly some psychological problems—patients who might have been discouraged from having surgery—may in fact be the patients who benefit most from surgery, given their poor nonsurgical outcomes,” said Dr. Pearson.

These results should help simplify the decision-making process for patients and surgeons, according to Dr. Pearson. “In an ideal world, patients would know their predicted treatment effect of surgery because it could be calculated using a model that estimates results based on individual characteristics. We learned that almost all predictors of surgical outcomes also predicted similar nonsurgical outcomes.

“For example, patients with depression, obesity, or medical comorbidities, smokers, and those taking narcotics did worse with surgery—something we already knew. But these patients did much worse with nonsurgical treatment,” he continued. “Although their absolute improvement with surgery was less, their treatment effect was similar to patients without these ‘red flags,’ suggesting that surgery should not be withheld due to these characteristics.”

Dr. Pearson noted that discussions on treatment effect should be part of informed decision making. “Patients are choosing between two treatments, and it is the relative difference between them—rather than the absolute change associated with either treatment alone—that is the important factor in decision making.”

Asked about the indications that mattered the most, Dr. Pearson went back to the original study. “All patients in SPORT had radicular symptoms for at least 6 weeks, neurological findings on physical exam, and imaging demonstrating a disk herniation consistent with their symptoms. All subgroups of patients who met these indications improved significantly more with surgery than with nonsurgical treatment.”

Coauthors for “SPORT Intervertebral Disk Herniation: Indications Matter Most” include Jon Lurie, MD, MS; Tor Tosteson, ScD; Wenyan Zhao, PhD; William A, Abdu, MD, MS; Sohail K. Mirza, MD, MPH; James N. Weinstein, DO, MS.

Disclosure information: Drs. Pearson, Zhao, Abdu, Mirza, Weinstein—no conflicts; Dr. Lurie—Foundation for Informed Medical Decision Making, Blue Cross Blue Shield, Sanofi-Aventis, Medtronic; Dr. Tosteson—no information

Mary Ann Porucznik is managing editor of AAOS Now. She can be reached at porucznik@aaos.org

Bottom line

• The SPORT trial found that patients with intervertebral disk herniation who met specific criteria did significantly better with surgery than with nonsurgical treatment.
• Patients in certain subgroups did better than those in other subgroups.
• Discussions of treatment effect should be part of informed consent.