Study Design. Randomized trial
with a concurrent observational cohort study.
To compare 8-year outcomes
care for symptomatic lumbar spinal stenosis
Summary of Background Data. Surgery
for spinal stenosis
has been shown to be more effective than nonoperative
treatment during 4 years, but longer-term data are less clear.
Surgical candidates from 13 centers in 11 US states with at least 12 weeks of symptoms and confirmatory imaging were enrolled in a randomized cohort or observational cohort. Treatment was standard, decompressive laminectomy versus
care. Primary outcomes
were SF-36 (MOS 36-Item Short-Form Health Survey) Bodily Pain and Physical Function scales and the modified Oswestry Disability Index assessed at 6 weeks, 3 months, 6 months, and yearly up to 8 years.
Data were obtained for 55% of participants in the randomized group and 52% of participants in the observational group at the 8-year follow-up. Intent-to-treat analyses showed no differences between randomized cohorts; however, 70% of those randomized to surgery
and 52% of those randomized to nonoperative
had undergone surgery
by 8 years. As-treated analyses in the randomized group showed that the early benefit for surgery
out to 4 years converged over time, with no significant treatment effect of surgery
seen in years 6 to 8 for any of the primary outcomes
. In contrast, the observational group showed a stable advantage for surgery
in all outcomes
between years 5 and 8. Patients who were lost to follow-up were older, less well-educated, sicker, and had worse outcomes
during the first 2 years in both surgical and nonoperative
Patients with symptomatic spinal stenosis
show diminishing benefits of surgery
in as-treated analyses of the randomized group between 4 and 8 years, whereas outcomes
in the observational group remained stable. Loss to follow-up of patients with worse early outcomes
in both treatment groups could lead to overestimates of long-term outcomes
but likely not bias treatment effect estimates.
Level of Evidence: 1