Injections for back pain: The evidence is weak

It’s been a while since I did a cycling topic.

As I was skimming thorough the Journal of the American Medical Association recently, I came across this review article on spinal injection therapy for low back pain. It was a shocker.

Two factors brought my attention to the article. First, almost all the cyclists or runners I know have been beset with either back pain or sciatica (referred pain or weakness down the leg). In fact, in some cases, back issues have ended their competitive careers. I too have been flattened with low back pain. It was awful. The other reason to pay attention to the review is the huge numbers of requests I receive from atrial fibrillation (AF) patients who are asking to stop their anticoagulant (blood thinner) for a spinal injection.

Background

Low back issues are even more common than AF. In the US, low back pain accounts for 2% of all doctor’s visits and is the fifth most common reason for visits to primary care. That makes perfect sense, doesn’t it? The same risk factors for heart disease, not moving enough and eating too much, also increase the risk of skeletal issues in the low back. The waiting room of the orthopedist looks very similar to the cardiologist.

Since I am no expert in orthopedics, I will write most of this post from a journalistic standpoint. The facts in the review are striking enough; they don’t need much editorial. My comments will be at the end.

5 facts from the review article

1. There is substantial variation in the use of injections. One study found relatively few providers are responsible for a disproportionately high percentage of injections. The authors of the study called it a“pattern of marked [overuse] by a minority of providers.” There is no data on whether high use rates associate with better outcomes.

2. Not all injections are the same. There are different targets (epidural, facet, discs, and ligaments for example), and different drugs injected. (local anesthetics, steroids, pain meds etc.). Injections are performed in different stages of disease: acute, subacute and chronic. All this variation makes it a tough topic to review.

3. One of the best tools for evaluating the benefits of a treatment is to do a systematic review of all the world’s literature. The Cochrane Collaboration did such a study for spinal injections in 2008. The researchers found that only 6 of 18 trials showed significant results for at least one outcome in favor of the injection. No clear pattern of benefit emerged. The researchers concluded: “There is insufficient evidence to support the use of injection therapy in subacute and chronic low-back pain. However, it cannot be ruled out that specific subgroups of patients may respond to a specific type of injection.”

4. A more recent pooled analysis of 25 studies looked specifically at epidural injections for sciatica. Here, at least there was a very small (6-point on a scale of 0-100) improvement in the short-term. No long-term benefit was noted. The authors concluded: “The small size of the treatment effects raises questions about the utility of this procedure in the target population.”

5. Review of guidelines show only one country (Belgium) recommends spinal injections. The US, UK, and Europe simply do not recommend injection therapy for low back pain. Rather, the guidelines start with education, “back schools,” NSAIDs (editorial comment – be careful), opioid analgesics, back exercises, spinal manipulation, rehabilitation, and behavioral therapy.

The review article concludes:

Patients with low back pain differ in their clinical presentation and may respond differently to treatments. Injection therapy of any kind may be beneficial in individual cases or subgroups. Nevertheless, given the weak scientific evidence base and the availability of noninvasive and more effective alternatives, physicians and policy makers should not recommend the use of injection therapy for patients with low back pain and sciatica.

My comments

This was very surprising. I had no idea that the evidence base for spinal injections was so weak. The concept of putting anti-inflammatory drug right on the source of inflammation makes perfect sense. It hits the problem area without exposing the patient to the risk of systemic exposure to steroids or non-steroidal drugs. You would have thought comparison studies would have strongly favored local injections. But that’s the thing with evidence-based medicine: just because something makes sense, and smart doctors think it so, does not mean it is so.

Spinal injection therapy is an important topic because many of the patients referred for injections are older folks on anticoagulant drugs. Recent studies in the AF literature make it clear that interrupting anticoagulant drugs can be risky. We also know “bridging” patients with (lovenox) shots carries risk. Again we get into net clinical benefit: you don’t mind taking the risk of being off anticoagulation if the benefit is great. This review of the literature on spinal injections suggests otherwise.

The wide-angle overriding view of the matter is always the same in medicine. It’s best to avoid the need for treatment. Human disease is never 100% avoidable, but a healthy and balanced (emphasis especially on balanced) lifestyle reduces the risk of facing tough decisions. And when disease strikes, if it is safe to wait, taking a conservative approach, giving the body time to heal itself, is often just as good as having a sharp object stuck into you.

A final caveat on the JAMA review article. The authors are PhD researchers from a quality healthcare institute. They are not orthopedists. That might have resulted in a biased selection of the literature. An orthopedist/pain interventionalist perspective might have been different.

John Mandrola is a cardiologist who blogs at Dr John M.

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