Very few studies have followed lumbar spinal stenosis (SpS) patients for 8-10 years after surgery, and these have generally showed a persistent long-term benefit of surgery but somewhat worsening outcomes over time.1,2 Studies evaluating outcome predictors have generally looked at medium-term outcomes out to 4 years.3 In order to address the gap in the literature evaluating long-term outcome predictors in SpS, Dr. Tuomainen and colleagues from Finland evaluated the associations between smoking status, BMI, history of prior lumbar surgery, self-rated health status, and duration of painkiller use prior to surgery and post-operative Oswestry Disability Index (ODI) and visual analog scale (VAS) pain scores out to ten years after decompressive surgery. Of the original cohort of 102 patients, 72 were available for follow-up at 10 years after surgery (17 had died and 13 were unavailable). Overall, patients improved significantly from a mean baseline ODI score of 43 to 29 at 10-year follow-up. Similarly, VAS scores improved significantly from 56 to 33. In looking at the subgroup analyses, patients with worse self-rated health and use of painkillers for over 12 months had worse baseline ODI and VAS scores. Univariate analyses demonstrated that smokers' ODI scores at 10 years were only 6 points better than baseline compared to a 15-point improvement in non-smokers. Those with poor self-rated health had significantly worse 10-year ODI scores compared to those with good self-rated health (38 vs. 26), though a similar change score from baseline. Patients who had been taking painkillers for less than 3 months at baseline had significantly better ODI scores at 10 years compared to those taking painkillers for over 12 months (19 vs. 35) and improved about 5 points more compared to the chronic use group. Multivariate analysis indicated that not smoking, no prior lumbar surgery, better self-rated health, and use of painkillers for less than 12 months were associated with better ODI and VAS scores over the 10 year follow-up period.
The authors have made a nice contribution to the literature by looking at outcome predictors over 10 years following lumbar decompression surgery for SpS. Their findings support similar findings in other studies that have identified smoking, revision surgery, poor general health status, and pre-operative opioid use as predictors of worse surgical outcomes. Like all long-term follow-up studies, this one was limited by loss to follow-up. However, 70% follow-up at 10 years is relatively good, especially considering that more than half of those lost to follow-up died. Additionally, those who remained in the study were relatively similar to those who were lost to follow-up. Most subgroup analyses have limited statistical power due to the low numbers in many subgroups, and this study is no exception. There were only 18 smokers and 12 patients who had prior lumbar surgery. The authors did not make it clear if the multivariate analysis controlled for baseline differences, so it is hard to determine if the observed outcome differences were due to the baseline differences or differential response to surgery. Finally, there was no non-operative control group, so it could not be determined if the subgroups with worse surgical outcomes would actually have a lower treatment effect (i.e. change score in the surgery group – change score in the non-operative group). The Spine Patient Outcomes Research Trial (SPORT) reported extensive subgroup analyses evaluating outcome predictors following surgical and non-operative treatment for SpS based on 4-year longitudinal follow-up of ODI scores.3 Patients with revision surgery were excluded from SPORT, but all of the subgroups identified as predicting worse outcomes in the current study also predicted worse surgical outcomes in SPORT (i.e. smoking, multiple medical comorbidities, and taking opioids at baseline). However, only smoking was associated with a worse treatment effect of surgery. This was because those with multiple medical comorbidities and opioid users had extremely poor non-operative outcomes, so they still improved more with surgery. Smokers had particularly poor outcomes in SpS and were the only subgroup that did not improve significantly from baseline following surgery. This is interesting as fusion was not performed in the SPORT SpS cohort, so increased pseudarthosis rate was not the driver of worse outcomes. Future studies should evaluate the cause of worse surgical outcomes following SpS surgery in smokers and determine if pre-operative smoking cessation improves outcomes.
Please read Dr. Tuomainen's article on this topic in the June 1 issue. Does this change how you consider long-term outcome predictors in SpS?
Adam Pearson, MD, MS
Associate Web Editor
1. Atlas SJ, Keller RB, Wu YA, Deyo RA, Singer DE. Long-term outcomes of surgical and nonsurgical management of lumbar spinal stenosis: 8 to 10 year results from the maine lumbar spine study. Spine (Phila Pa 1976) 2005;30:936-43.
2. Lurie JD, Tosteson TD, Tosteson AN, et al. Surgical versus nonoperative treatment for lumbar disc herniation: eight-year results for the spine patient outcomes research trial. Spine (Phila Pa 1976) 2014;39:3-16.
3. Pearson A, Lurie J, Tosteson T, Zhao W, Abdu W, Weinstein JN. Who should have surgery for spinal stenosis? Treatment effect predictors in SPORT. Spine 2012;37:1791-802.