Adding spinal fusion to decompression surgery may not be associated with improved disability outcomes or reoperation risk among patients with degenerative lumbar spondylolisthesis.
Investigators conducted a cohort study using a target trial emulation framework, drawing on the Norwegian Registry for Spine Surgery and the NORDSTEN-DS randomized trial. They included 2,252 patients aged 18 to 80 years with degenerative lumbar spondylolisthesis and back or leg pain lasting at least 3 months, 1,446 of whom underwent decompression alone and 806 of whom underwent decompression with fusion. The cohort included 236 patients enrolled in the randomized trial and 2,016 treated in routine clinical practice. Registry data covered January 2007 to July 2021.
The primary outcomes were disability at 12 months, measured using the Oswestry Disability Index (ODI), and subsequent spine surgery within 12 months. Secondary outcomes included back and leg pain intensity, quality of life, treatment satisfaction, operative duration, hospital length of stay, and perioperative complications. Inverse probability weighting adjusted for measured baseline differences between treatment groups and examined prespecified subgroups according to sex, age, smoking status, body mass index (BMI), back pain intensity, and American Society of Anesthesiologists grade.
At 12 months, adjusted mean ODI scores were 22.3 following decompression alone and 20.0 following decompression with fusion. Lower scores indicated less disability, but the difference did not establish a clear advantage for fusion. The investigators found no clear differences in back and leg pain intensity, quality of life, or treatment satisfaction between the groups.
The adjusted risk of subsequent spine surgery within 12 months was 7% following decompression alone and 6% following decompression with fusion, with no clear difference between groups. Decompression alone was associated with fewer perioperative complications, occurring in an estimated 5% of patients vs. 9% of those undergoing fusion. The risk of subsequent surgery for complications was lower following decompression alone.
Decompression alone was associated with operations that were about 85 minutes shorter and hospital stays that were 1.9 days shorter compared with decompression with fusion. Other postoperative complication outcomes did not differ clearly between groups.
There was no clear evidence that the prespecified patient characteristics modified the comparative effectiveness of the procedures.
In an exploratory analysis, male participants with a BMI of at least 30 kg/m² had worse disability outcomes following decompression with fusion, with an estimated 12.8-point ODI difference favoring decompression alone. The difference in treatment effects between male participants with a BMI of at least 30 kg/m² and those with a lower BMI was 16.5 points. However, this finding emerged from a post hoc analysis and requires further investigation.
The study had several limitations. Because most patients received treatment in routine clinical practice rather than through random assignment, residual confounding remained possible, particularly from unmeasured differences in the severity of vertebral slippage. Disability outcomes were missing for about 17% of patients at 12 months, although sensitivity analyses produced similar findings. The study may have lacked sufficient statistical power to detect small subgroup effects and was based on patients treated in Norway. Therefore, the findings may not generalize to other health care settings. Follow-up was limited to 12 months.
The findings were consistent with previous randomized trials reporting limited additional benefit from fusion for degenerative lumbar spondylolisthesis.
“Patient subgroups did not have differential effects from the addition of fusion to decompression at 12 months,” wrote lead study author Harrison J. Hansford, PhD, of the University of New South Wales in Australia, and colleagues.
Full disclosures of the study authors can be found in the study.
Source: Annals of Internal Medicine
