Interlaminar Lumbar Epidural Steroid Injection: Efficacy

The overall efficacy of IL LESI treatment at 6 months is 50%, but of this 50% of patients the median duration of relief is about a year and a half.















The efficacy of Interlaminar Lumbar Epidural Steroid Injections has been an accepted fact within the pain community and a subject of debate outside of this community for over 30 years. The reasons for this discrepancy lie in the design of most of the studies and an arcane statistical phenomenon known as the restriction effect (see the Blog entitled Lessons from the Parachute Trials, The Restriction Effect).


First for the positive, everyone in the field has seen remarkable success stories with IL LESIs, people who come in for the first visit in a wheel chair and walk in for the second visit without so much as a cane. We have also seen cases where there has been no apparent relief of chronic pain or where substantial relief occurs but lasts for only days to weeks. How do you explain such results? I start by telling patients that the overall results are 50/50 because back pain is a mixed bag.


There are literally dozens of conditions that can cause back pain and each one of them will respond differently to epidural steroids. What do the studies say? Sadly most of the studies do not differentiate between the different causes. In an analogy to the article on the Taxonomy of Fibromyalgia, most authors are saying that epidural steroids are not effect in the treatment of fruit salad, whereas they might be in the treatment of apples or oranges.


Another problem that I have to deal with in clinical practice and in interpreting the data is the definition of success and failure. I define success for the patients as relief of 50% or more of their pain that lasts for 6 months or longer. I do so for two very practical reasons. The first is that 50% relief of pain usually translates into a meaningful improvement in the quality of life for most patients whereas less of an improvement doesn’t. Secondly, the injection of epidural steroids is not a curative treatment, but rather a form of palliation that can be repeated up to every 6 months. As such, patients who obtain at least 6 months of relief are eligible for another set of injections, whereas the others do not.


What do the studies tell us about pain relief? This is perhaps one of the clearest examples of the restriction effect I know of. Virtually all show significant initial improvement. Most will show statistically significant improvement at 6 weeks. Most show a trend toward improvement at 6 months, but this trend is not usually significant at the p=0.05 level. But this is exactly what one would expect from clinical practice. Remember, 50% of these people will fail at 6 months or less, many within a matter of weeks and this brings the average for the length of relief down tremendously. A much more meaningful statistic is median duration of relief. Of those patients who experience at least 6 months of relief the median (not mean) duration of relief is actually 18 months.

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