“Both surgical and non-operative treatment for disc herniation is not as effective in obese patients, but obesity does not affect the clinical outcome of surgery for stenosis,” Jeffrey A Rihn, Thomas Jefferson University Hospital, Philadelphia, told delegates at the North American Spine Society annual meeting in Orlando, USA.
“Infection and re-operation rates are higher in obese patients following surgery for degenerative spondylolisthesis, but non-operative treatments may not be as effective as surgery in obese patients with stenosis or degenerative spondylolisthesis,” he said.
Obesity is very common in the adult population and there are conflicting reports in the literature about whether obesity affects the treatment outcome for degenerative diseases of the lumbar spine.
Rihn and team analysed SPORT data to assess the effect of obesity on outcomes following treatment for lumbar degenerative conditions.
SPORT was conducted at 13 centres in 11 states and contained data on disc herniation, stenosis and spondylolisthesis of the lumbar spine. The investigators of this study saw this as an “as treated” analysis. They combined data from randomised controlled trials and observational cohorts for disc herniation, stenosis and degenerative spondylolisthesis and stratified patients into two groups based on body mass index. Group A had patients with body mass index equal to or greater than 30, and Group B had patients with a body mass index less than 30.
“In terms of baseline patient characteristics, obese patients had less education, lower income and increased co-morbidities such as hypertension, diabetes and depression. Baseline primary outcome measures showed that obese patients did worse than non-obese patients except in the case of spinal stenosis.
Disc herniation
At four-year follow-up, there was no difference between obese and non-obese patients in terms of SF-36 bodily pain scores.
Stenosis
Obese patients who were treated surgically had no differences with regard to operating room time, blood loss or length of stay. There was no increase in infection, complication, or re-operation rate.
Degenerative spondylolisthesis
Obese patients who were treated surgically had greater operative time (220 minutes vs. 197 minutes, p=.008). There was no difference in blood loss or length of stay.
They also had a higher postoperative infection rate (5% vs. 1%, p=0.05) and twice the re-operation rate at 4-years follow-up (20% vs. 11%, p=0.01).
“In terms of treatment effect, both obese and non-obese patients improved more with surgery than with non-operative treatment in the disc herniation, stenosis and degenerative spondylolisthesis groups. For disc herniation, the treatment effect of surgery is similar for obese and non-obese patients. For stenosis, there is greater Oswestry Disability Index treatment effect for obese patients when compared to non-obese patients due to poor non-operative outcomes among obese patients. In degenerative spondylolisthesis, there was greater SF-36 PF treatment effect for obese patients due to poor non-operative outcomes among obese patients,” Rihn explained.
