Friday, March 18, 2011

Lumbar Fusion Surgery for Back Pain Questioned

Back PainThere have been variable successes of lumbar-spine fusion surgeries reported in patients with work-related low-back injuries causing chronic pain. A new study proposes that long-term outcomes, including return to work, are actually better without the surgery, but there are some possible biases in this investigation to consider.

Writing in the February 15, 2011 edition of the journal Spine, researchers report a retrospective case-control study of patients receiving workers’ compensation who either underwent lumbar-spine fusion (arthrodesis) surgery for job-related back injuries (cases) or had similar injuries and chronic pain but did not undergo surgery (controls) [Nguyen et al. 2011]. Multiple outcomes were assessed at 2 years after the date of injury (for controls) or 2 years after date of surgery (for cases) including: return to work (RTW), permanent disability, and opioid utilization in all subjects; and, also postsurgical complications and reoperation status for subjects having lumbar fusion.

Using data from the Ohio Bureau of Workers' Compensation System the research team identified 725 workers with chronic low back pain who underwent spinal fusion surgery, most commonly for degenerative disc disease, herniated discs, or nerve root disease (radiculopathy). The controls consisted of a random sample of 725 patients who underwent nonsurgical, conservative treatments (such as analgesics, physical therapy, exercise, etc.). The average age of all subjects was 39 years and all had been healthy working individuals at the time of on-the-job injury.

At the time of followup, almost all categories of outcomes were worse for patients who underwent lumbar fusion surgery. Just over one-fourth (25.93%) of lumbar fusion patients had returned to work compared with two-thirds (66.62%) of those treated without surgery. Among patients who underwent surgery, 36% experienced some type of complication and 27% required repeat surgery. Furthermore, 11% of the surgical patients were classified as having permanent disability but only 2% of those treated without surgery. Nearly 85% of surgical patients were continuing to take opioid analgesics compared with 49% of controls, and the average daily dose of morphine-equivalent oral opioids taken by surgical patients was higher after than before surgery.

There were two other interesting, but unexplained, findings: (1) The more rehabilitative and vocational therapy sessions provided to either those having surgery or controls, the less likely they were to return to work; and (2) the odds of their returning to work were decreased in patients having legal representation regarding their workers’ compensation claims. Also of interest, total days away from work was a strong predictor of poor return to work status, regardless of surgical or nonsurgical treatment; in fact, control patients (without surgical intervention) who had prolonged days off work had lower odds of returning to work than the surgical cases.

In sum, the researchers conclude that lumbar-spine fusion for the treatment of lower-back injury in a workers’ compensation setting is largely ineffective, since it is associated with significant increases in disability, prolonged time away from work, poor return to work status, and ongoing opioid analgesic use. Other important predictors of lowered prospects for return to work include the length of time off from work, surgical complications or re-operations, and having legal representation.

COMMENTARY: It is important to note that this study included data from a single state and from the perspective of the workers’ compensation system. A natural bias is to favor approaches that will return injured workers back to their jobs in the shortest possible timeframes and at the lowest cost, which can be beneficial for both workers and the compensation system.

It is unclear in this study whether the researchers are commenting more on qualities of injured workers that affect their return to work, or the value of lumbar-spine fusion as an appropriate and effective surgical intervention overall. In those who had surgery, the researchers note that the type of lumbar fusion procedure was not a predictor of return to work status, but that such surgery is controversial for disc degeneration or herniation, and/or radiculopathy — which affected 84% of cases. Rather, they claim the surgery has had better results in persons with spondylolisthesis [anterior displacement of vertebrae], traumatic fracture, and tumor.

However, they do not comment on diagnostic or prognostic factors influencing the surgical decision, as opposed to more conservative nonsurgical approaches, or the conditions that might have fostered surgical complications. It seems unlikely that injured workers would elect to have a major surgical procedure if it had not been presented as the most appropriate option for their particular condition. Yet, the authors broadly state, “Lumbar spine fusion does not seem to be an effective operation for the worker’s compensation subjects” evaluated in their study [emphasis added].

A further bias appears to be directed toward long-term opioid analgesic therapy for noncancer chronic pain, which the authors note “may not be in a patient’s best interest.” They state, “Continued usage of opioids in the workers’ compensation system without long-term randomized trials and/or large population studies is not recommended in light of these findings.” Again, there seems to be an implication that injured workers are somehow different from the general population in terms of treatment that is best for them.

We do not know from this study how the patients who avoided surgery were able to recover and return to work in greater numbers and more rapidly; that is, what was different about these workers, what therapies were used, and why did fewer of them rely on opioids for pain relief? This is particularly puzzling in light of the paradoxical finding that increased rehabilitation or vocational therapy sessions, not fully described in the report, resulted in poorer outcomes.

The authors do not declare any funding sources or other conflicts of interest relating to their work that might have biased their study. However, an unstated, somewhat subtle, implication appears to be that certain injured workers retain legal counsel and elect to have surgery so they can avoid going back to work and can prolong and increase their use of opioids. While this seems absurd, there is a history in the workers’ compensation field literature of denigrating injured workers as slackers who are unhappy at their jobs and would seek excuses to avoid return to work.

For example, we have previously noted the work of critics such as Norton M. Hadler, MD, and colleagues who, for years, described psychosomatic aspects of chronic pain disorders in pejorative terms [eg, Hadler 1978; Hadler et al. 2007]. For example, they have considered work-related cumulative strain and backache disorders as mere “surrogate complaints” reflecting psychological distress over poor working conditions and unrewarding work rather than as bona fide maladies. They write: “No physician, employer, human resource professional, claims adjuster, or worker is likely to realize that the backache is intolerable and disabling because the job is intolerable, unsatisfying, or insecure” [Hadler et al. 2007].

The inference is that many workers with pain complaints are psychologically unfit malingerers hoping to take advantage of workers’ compensation or other assistance for conditions having little or no basis in structural or organic pathology. This current study also appears to raise pessimistic doubts along those lines, and may become part of the literature cited in rulings or guidelines that regulate workers’ compensation policy. However, without prospective, controlled clinical trials to better assess surgical compared with alternative approaches for back injuries affecting the lumbar spine, this perspective could be short-sighted and misguided.

> Hadler [misspelled as ‘Hauler’ online] NM. Legal ramifications of the medical definition of back disease. Ann Intern Med. 1978;89(6):992-999 [
abstract here].
> Hadler, NM, Tait RC, Chibnall JT. Back pain in the workplace. JAMA. 2007;297(14):1594-1596 [
abstract here].
> Nguyen TH, Randolph DC, Talmage J, et al. Long-term Outcomes of Lumbar Fusion Among Workers’ Compensation Subjects: A Historical Cohort Study. Spine. 2011(Feb 15);36(4):320-331 [
full article available here].