by Anthony J. Brown, MD

Last Updated: 2008-02-20 17:00:30 -0400 (Reuters Health)

NEW YORK (Reuters Health) – As a treatment for symptomatic lumbar spinal stenosis, decompressive surgery provides greater pain relief and functional improvements than does nonsurgical care, according to the as-treated analysis of a new study. Still, the findings suggest that watchful waiting can be a safe and viable option.

"As a spine surgeon, I’m happy to have evidence that surgery works for this specific diagnosis and that patients see improvements on all measures," lead researcher Dr. James N. Weinstein told Reuters Health. "But it was important to learn that those patients who did not have surgery…did not get worse and, in fact, in most cases they also saw some improvement."

The main message in this study is that patients with spinal stenosis have a choice, added Dr. Weinstein, from Dartmouth Medical Center in Lebanon, New Hampshire. "Surgery works, but non-surgical therapies and watchful waiting are options for patients who prefer that course. This study gives us, for the first time, the best available, evidence-based information we can share with our patients."

Spinal stenosis is the most common reason for decompressive lumbar surgery in older adults, according to their report in The New England Journal of Medicine for February 21st. Whether surgical treatment is more effective than medical therapy, however, was unclear.

In a 2005 Cochrane review, researchers concluded that limited data and heterogeneity of evidence made it impossible to definitively determine the optimal treatment for spinal stenosis. Most of the trials included in this review were small and featured patients with and without degenerative spondylolisthesis.

To address this latter issue, the researchers included only patients with spinal stenosis, not with spondylolisthesis. This is the first randomized trial focusing exclusively on isolated spinal stenosis, they note.

The Spine Outcomes Research Trial (SPORT) involved patients with at least 12 weeks of symptoms who were enrolled in an observational group or a randomized cohort at 13 spine clinics in the US. Bodily pain and physical function were assessed with the Medical Outcomes Study 36-item Short-Form General Health Survey (SF-36) and with the modified Oswestry Disability Index administered at 6 weeks, 3 months, 6 months, and 1 and 2 years.

Overall, 365 patients were in the observational cohort and 289 were in the randomized cohort. At 2-year follow-up, 67% of patients randomized to surgery and 43% of those initially randomized to nonsurgical care had undergone surgery, the investigators point out.

On the intention-to-treat analysis of the randomized cohort data, surgery provided significantly better pain relief than did nonsurgery with a mean difference in change from baseline on the SF-36 of 7.8. As noted, physical function, as measured on the Oswestry Disability Index, did not differ significantly between the groups.

The as-treated analysis, which included patients from both cohorts, showed that surgery provided better pain relief and functional outcomes than did nonsurgical care. Moreover, these benefits were apparent by 3 months and persisted for 2 years.

According to the authors, the main limitation of SPORT was the high degree of nonadherence in the randomized cohort; many patients assigned to nonsurgical therapy were treated with surgery and vice versa.

Still, they note that "the large effects seen in the as-treated analysis and the characteristics of the crossover patients suggest that the intention-to-treat analysis underestimated the true effect of surgery."

N Engl J Med 2008;358:794-810.

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