“The management of degenerative spondylolisthesis associated with spinal stenosis remains controversial, write James N. Weinstein, DO, MS, from Dartmouth-Hitchcock Medical Center in Lebanon, New Hampshire, and colleagues. Surgery is widely used and has recently been shown to be more effective than nonoperative treatment when the results were followed over two years. Questions remain regarding the long-term effects of surgical treatment compared with those of nonoperative treatment.
The randomized cohort or observational cohort at 13 centers enrolled surgical candidates who had imaging showing degenerative spondylolisthesis with spinal stenosis and who had symptoms for at least 12 weeks. Usual nonsurgical management or standard decompressive laminectomy, with or without fusion were the treatment options. The main endpoints of the study were bodily pain and physical function scores on the Short Form-36 and the modified Oswestry Disability Index at 6 weeks, 3 months, 6 months, and annually up to 4 years.
In the randomized cohort, 304 patients enrolled of which two thirds (66%) of those assigned to surgical management underwent surgery by 4 years, whereas approximately half (54%) of those assigned to nonsurgical management received surgery by 4 years. In the observational cohort that enrolled 303 patients, most (97%) of those who chose surgery received the surgery, whereas one third (33%) of those who chose nonsurgical management ultimately underwent surgery.
Treatment outcomes between the operative and nonoperative groups were not significantly different, based on intent-to-treat analysis of the randomized cohort at 3 or 4 years. However, this analysis was limited by nonadherence to the assigned treatment. So the investigators performed an as-treated analysis pooling the randomized and observational cohorts, with adjustment for potential confounders.
Clinically important benefits of surgery that had been previously reported through 2 years were maintained at 4 years in the as-treated analysis. Treatment effects were 15.3 for bodily pain (95% confidence interval [CI], 11 – 19.7), 18.9 for physical function (95% CI, 14.8 – 23), and –14.3 for the Oswestry Disability Index (95% CI, –17.5 to –11.1).
The surgical management benefits at 2 years regarding secondary outcomes of bothersomeness of back and leg symptoms, overall satisfaction with current symptoms, and self-rated progress were also maintained at 4 years.
Compared with patients who are treated nonoperatively, patients in whom degenerative spondylolisthesis and associated spinal stenosis are treated surgically maintain substantially greater pain relief and improvement in function for four years, the study authors write.
The study drawbacks include nonadherence to assigned treatment and heterogeneity of the treatment interventions.
In the as-treated analysis, combining the randomized and observational cohorts of patients with spinal stenosis secondary to degenerative spondylolisthesis, those treated surgically were found to have significantly greater improvement in scores for pain, function, satisfaction, and self-rated progress over four years compared with patients treated nonoperatively, the study authors conclude. The results in both groups were stable between two and four years.
