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Tuesday, November 21, 2006

Surgical versus nonoperative treatment of herniated lumbar disk-a randomized trial

The SPORT trial results are published in the November 22,2006 issue of JAMA. The Spine Patient Outcomes Research Trial was a 501 patient randomized trial involving 13 centers over a 4 1/2 year period. All patients had imaging confirmed lumbar intervertebral disk herniation with persistent symptoms and signs lasting for at least six week.Surgery was a diskectomy with at most a small portion of the superior facet being removed and a disc fragment removed and the nerve root decompressed.

It is generally agreed that the appropriate way to analyze results in a randomized trial is by a " intent-to-treat" analysis. However, in this case because there was such a large percentage of patients who crossed over to the other treatment arm and a significant amount of missing data that the intention-to-treat analysis was not informative about which approach was better and in the words of the authors "conclusions about the supriority or equivalence of the treatments are not warranted based on the intent-to-treat analysis alone". However, it did show small and non statistically significant advantages to the surgical approach for most measures with a statistical improvement in sciatica.Here is an excellent discussion of intent to treat analysis and the traps involving in attempts to consider the problems of lack of adherence and loss of data in a clinical trial from Dr. Gerald Dallal,a Yale epidemiologist .

When one analyzes the as-treated groups there was a definite advantage to surgery.But the validity of this conclusion is clouded by the concern about confounders as the two groups were no longer randomized. So it seems that we cannot know if surgery is better or not regardless of which analytic technique is used. If you do look at the groups as treated there are much larger effects in favor of surgery which did not disappear after correction for recognized covariates.

It seems that at the end of the day this fairly large, multi center multi year trial did not provide the answers to the questions for which the trial was designed. So what is next?

One of the two editorialists in the same issue of JAMA, Dr. David R. Flum, believes the only way to answer the still unanswered questions raised in SPORT is to have a randomized, placebo controlled trial. Placebo control in this sense means sham operations. The authors of SPORT ruled out sham operations because they believed subjecting a control group to general anesthesia with its attendant risks was not ethical. Flum disagrees. He says that sham procedures would be ethically justified on the "question of community exposure to an invasive, high risk procedure with associated risk ". I think he is saying that since large numbers of folks are"exposed" to the risk of diskectomy a sham controlled RCT would be justified to learn the answer to the question, " Is the procedure justified?" This, I think, is a type of public health style justification implying that diskectomy is some sort of risk that people are exposed to against their will as opposed to a decision made by the individual patient to undergo the procedure.

I realize that sham surgery RCTS have been beneficial in the past at times showing the lack of value of certain operative procedures, internal mammary ligation for angina for one, but the dramatic improvement ones sees when someone with severe pain, and objective weakness, improves immediately after surgery is hard to attribute to a placebo effect particularly when the surgeon sees a nerve root being compressed and relieves that compression.

This and other trials have shown that after 2 years there may be little difference in the outcomes in the surgery and non surgical groups but when you have unrelenting neuropathic pain-for which typically usual analgesics work poorly-the option of quick relief is something I would opt for. In the long run the two approaches seem very similar in terms of outcome but remember what John Maynard Keynes said about the long run.

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