December 30, 2008 — A new study extends to 4 years the previously published 2-year results of research that found that spine surgery provides more rapid and greater relief in symptoms and a greater improvement in function than nonsurgical interventions for patients with lumbar disk herniation.
And while the surgery did not get patients back to work faster than nonoperative approaches, there is mounting evidence that surgery might be cost-effective.
“Patients, families, and insurance carriers or the government want to know how long this treatment effect is going to last. Is it short-term or does it have a long-term effect?” said 1 of the study authors, William Abdu, MD, from Dartmouth-Hitchcock Medical Center, in Lebanon, New Hampshire. “The answer is that so far, out to 4 years, the surgical group still did much better than the nonsurgical group. There were no major adverse complications in either treatment group, and that hasn’t changed out to 4 years.”
The updated results of the Spine Patient Outcomes Research Trial (SPORT) appear in the December 1 issue of Spine.
All Patients Improved
But although patients receiving surgery did better than those treated with physical therapy, exercise, and pain relievers, all patients in the study improved, a finding that “provides patients with more information to make decisions,” said Dr. Abdu.
SPORT compared outcomes of 1244 patients at 13 American spine clinics who had at least a 6-week history of a herniated disk in the lumbar spine causing back pain, leg pain, and other symptoms and who received either surgery (diskectomy) or nonsurgical treatments. Enrollment began in March 2000 and ended in November 2004. Surgery and nonsurgery cohorts were remarkably similar at baseline, and as of this current analysis, the overall mean age of subjects was 41.7 years.
The study includes 2 groups: 501 patients who were randomly assigned to either surgery (245) or nonsurgery (256), and 743 patients who chose between the 2 treatments (521 initially opted for surgery while 222 initially chose nonsurgical intervention).
Surgery consisted of a standard open diskectomy, while the nonoperative protocol included at least active physical therapy, counseling with home exercise instruction, and nonsteroidal anti-inflammatory drugs if tolerated.
Researchers used the Bodily Pain (BP) and Physical Function (PF) scales and a version of the modified Oswestry Disability Index (ODI) to assess mean changes from baseline at 6 weeks, 3 months, and annually. Secondary outcomes included work status and patient self-reported improvements.
At 4 years, 59% of those randomized to surgery had undergone surgery, but so had 45% of those randomized to nonsurgery. In the observational cohort, 95% of those initially choosing surgery and 24% of those originally opting for nonoperative treatment had received surgery. In total, 805 patients received surgery by 4 years. That meant that a total of 112 patients (24%) crossed from nonoperative treatment to surgery, although another 89 patients (19%) crossed from surgery to nonoperative treatment. Researchers categorized the outcomes into “intent to treat” (the original randomization treatment) and “as treated” (the treatment actually received regardless of original categorization.)
This crossover from 1 cohort to the other could have underestimated the effectiveness of surgery in the intent-to-treat analysis, Dr. Abdu told Medscape Neurology & Neurosurgery.
As-Treated Analysis Powerful
The crossover phenomenon made the observational, or “as-treated,” analysis all the more important, said Dr. Abdu. “The ‘as-treated’ analysis is so powerful because we could control for all those known variables that might influence outcome.” This, he added, made the study “very, very highly statistically controlled.”
At 4 years, the combined as-treated analysis found that those patients who received surgery had a better outcome in all but 1 measure. Pain scores were an average of 15 points improved on a 100-point scale for patients undergoing surgery compared with nonsurgical patients (mean change 45.6 vs 30.7). Surgical patients also had greater improvement in measures of physical functioning (44.6 vs 29.7) and disability (-38.8 vs -34.9). The treatment effect for surgery was noted as early as 6 weeks and persisted over the 4 years.
As well, 79.2% of the surgical group and 51.7% of the nonsurgery group reported major improvements in their status.
Overall surgical complications were similar in the randomized and observational cohorts. The most common surgical complication was dural tear, and there was no perioperative mortality. Rates of reoperation were about the same in both cohorts.
Asked for comment on these new findings from SPORT, James Bean, MD, president of the American Association of Neurological Surgeons, said the comparison of “intent-to-treat” and “as-treated” groups corrects a flaw contained in the original study design that credited treatment outcome to the original treatment plan.
In the current analysis, Dr. Bean said, “even a trial that wasn’t randomized showed the same difference in outcomes [as the randomized portion], so it’s almost like a valid way of looking at things without going through the problems of trying to randomize, he said in an interview. As it stands now, the study results are robust, he added.
“They’ve held up for 4 years, they’ve correctly identified the flaw in the reasoning, and I think it’s a well-done paper. I agree with everything that was concluded.”
Similar Return-to-Work Status
The only area where surgery group did not do significantly better than the nonsurgery group was in returning to work: 78.4% of patients compared with 84.4%. Work status is often seen as an important measure of success in spine-surgery patients, said the study authors. “However, return to work appears to be independent of treatment received and does not follow improvements in pain, function, or satisfaction with treatment,” they write.
Dr. Abdu stressed that the study showed that patients in the nonoperative group also had some improvements and that these persisted over 4 years as well. The goal of the research, he said, is not to prove 1 treatment right and another wrong but instead to provide patients with information to make informed treatment choices.
“For patients who don’t want an operation no matter how bad their pain is, this paper suggests that they will improve and they will not have complications — meaning paralysis — from nonoperative treatment, and they will do reasonably well,” he said. “On the other hand, you can tell those patients whose leg pain is severe and is limiting their function, who meet the inclusion criteria for SPORT and who are wondering how they will do with an operation, that statistically, based on averages, they will do very well; in fact they will do much better with surgery than without surgery, and the risks are extremely low.”
Whether the benefits of surgery will continue beyond 4 years remains to be proven. “We’re waiting for funding so we can follow these patients for many more years, up to 8 or 10 years,” said Dr. Abdu.
Cost-Effectiveness Data Mounting
In the meantime, cost-effectiveness research is building a case for surgery. A 2-year analysis referred to in the current study calculated the direct and indirect costs and benefits of surgery compared with nonoperative treatment for lumbar disk herniation and found that the quality-adjusted life-year (QALY), a measure of healthy years gained, for surgery relative to nonoperative care was $69,403 (95% CI, $49,523 – $94,999). “Surgery was certainly cost-effective” for this condition, said Dr. Abdu.
Another recently published analysis made similar calculations, but for patients with different spinal conditions within the SPORT cohort. An article in the December 16 issue of the Annals of Internal Medicine that compared the cost-effectiveness of spine surgery with nonoperative care for stenosis alone and for stenosis with spondylolisthesis found that after 2 years, surgery for spinal stenosis cost about $77,000 per QALY gained. However, surgery for spondylolisthesis cost about $115,000 per QALY gained, above the threshold of $100,000 at which procedures are considered cost-effective in the United States.
“The economic value of spinal stenosis surgery at 2 years compares favorably with many health interventions,” the authors conclude. “Degenerative spondylolisthesis surgery is not highly cost-effective over 2 years but could show value over a longer time horizon.”
In an editorial accompanying the Annals of Internal Medicine article, Jeffrey N. Katz, MD, and Elena Losina, PhD, from Brigham and Women’s Hospital, in Boston, commented that since costs are usually incurred in the first year but the advantages and some complications are not typically realized until after a decade or longer, it is still too early to determine true cost-effectiveness.
It is important to determine the costs of spine surgery, as back pain affects up to 80% of Americans at some point in their life, Dr. Abdu added. The estimated cost of back pain care — including surgical and nonsurgical interventions — is about $100 billion a year. “We want to be sure that patients are receiving the best possible information and care for their spine problems and that these are cost-effective treatments and procedures.”
The study was supported by the National Institute of Arthritis and Musculoskeletal and Skin Diseases (NIAMS), the Office of Research on Women’s Health, the National Institutes of Health, and the National Institute of Occupational Safety and Health of the Centers for Disease Control and Prevention. The Multidisciplinary Clinical Research Center in Musculoskeletal Diseases is funded by NIAMS. Coauthor Dr. Jon D. Lurie, also from Dartmouth-Hitchcock Medical Center, is supported by a research career award from NIAMS.
Spine. 2008;33:2789-2800. Abstract