Adam Pearson, Department of Orthopaedics, Dartmouth Medical School, New Hampshire, USA, and his co-authors have published a study in Spine that shows greater treatment effect of surgery for intervertebral disc herniation, in patients who are married, those without joint symptoms, and those who had worsening symptoms at baseline.
Examining data from the SPORT study, which found surgery (via standard open disctectomy with examination and decompression of the involved nerve root) to be more effective than non-surgery for managing patients with intervertebral disc herniation, Pearson et al used 37 variables to define subgroups for characteristics that might modify the treatment effect of surgery. They then used a multivariate analysis to identify independent treatment effect modifiers from variables with significant subgroup interactions.
As might be expected, patients who met the study’s strict inclusion criteria for surgery improved more with surgery than with non-operative treatment—regardless of their individual characteristics. However, among the other characteristics, being older than 41 years, the absence of joint problems, duration of symptoms for more than six months, being married, and having worsening symptoms at baseline were all associated with a greater treatment effect of surgery.
After performing the multivariate analyses, being married, the absence of joint problems, and worsening symptoms at baseline were the only characteristics found to be independent modifiers of treatment effect.
Pearson et al reported that married patients had similar surgical outcomes to single patients, but that non-surgical single patients improved significantly more than non-surgical married patients. They explained that this finding lead to the significantly higher treatment effect of surgery observed in the married patients. They wrote: “The current study does not provide an explanation for why single patients did better with non-operative treatment, though marital status is likely a marker for other characteristics that were responsible for these outcomes.” Pearson told Spinal News International that it was possible that single patients needed to be more self-sufficient. He added: “Their socioeconomic status might not allow for them to take time away from work to recover from surgery if they do not have a spouse to support them. As such, they may be more motivated to improve without surgery. Unfortunately, our data do not allow us to test this or other explanatory hypotheses.”
In their article in Spine, Pearson et al wrote that the finding on the presence of joint problems was associated with a lesser treatment effect and may represent a “ceiling effect” in that the improvement in the Oswestry Disability Index seen in surgery patients with joint problems at baseline may have been limited by those problems “even if their spine symptoms were completely resolved”.
According to Pearson et al, patients who had worsening symptoms at baseline had a greater treatment effect of surgery. It was “not surprising” as “these patients were worsening with non-operative treatment at baseline yet had surgical outcomes that were nearly as good as patients who were getting better at baseline.”
Pearson et al concluded their findings by saying: “Future work will involve the creation and evaluation of real-time computer models that can be used by individual patients with their providers in the clinical setting to predict their likely surgical and non-operative outcomes.”
Pearson added: “The bottom line of the study was that all subgroups improved more with surgery than with non-operative treatment, and all patients who meet SPORT’s inclusion criteria should probably be offered surgery. Given that significant improvement can also occur with non-operative treatment, a good shared decision making process is essential.”