Thursday, May 23, 2013

Injections for Low-Back Pain Disparaged

InjectionsLow-back pain will affect most adults at some time during their lifetime, and is the 5th most common reason for primary care office visits in the United States. One treatment option for low-back pain is injection therapy, which received notoriety in 2012 after a deadly fungal meningitis outbreak in the U.S. caused by contaminated steroid-injection solutions. Writing in the Journal of the American Medical Association (JAMA), a team of investigators from the Netherlands offers their viewpoints as to why these interventional procedures for low-back pain should be avoided.

In their commentary, J. Bart Staal, PhD — from the Scientific Institute for Quality of Healthcare, Radboud University Nijmegen Medical Centre, Nijmegen, the Netherlands — and colleagues observe that there is substantial variation in the use of injection therapy by practitioners [Staal et al. 2013]. The average number of injection procedures per patient may vary from 1 to 9 per year and encompasses a diverse mix of interventions. First, there is wide variation in indications and targeted locations, such as facet joints, epidural space, intervertebral disks, ligaments, muscles, or trigger points. Second, there may be differences in pharmaceutical agents — eg, corticosteroids, local anesthetics, and a range of other drugs such as NSAIDs, morphine, sodium hyaluronate, benzodiazepines, and vitamin B12 — and the dosages used.

Injections may be applied in different stages of low-back pain or sciatica (acute, subacute, and chronic), and sometimes also for diagnostic purposes. This heterogeneity regarding purpose and content of injection therapy has to be considered when evaluating studies of the effects of injection therapy in patients with low-back pain. Staal et al. describe two systematic reviews and meta-analyses as examples:

  • The effects of various types of injection therapy for subacute and chronic low-back pain were previously evaluated by Staal and colleagues in a 2008 Cochrane Systematic Review [Staal et al. 2008]. The researchers identified 18 randomized controlled trials (RCTs), with interventions ranging from epidural or facet joint injections with corticosteroids or anesthetics to muscular or ligament injections with anesthetics or vitamin B12. Control groups received placebo or other treatments.

    Results of the studies varied, but only a third of the RCTS (6/18) showed significant results for at least 1 outcome (eg, pain, disability, generic health status) favoring one of the active treatments, and only 4 of those favorable effects could be considered as clinically important. No clear pattern emerged from these 6 trials.
     
    In sum, the studies were too heterogeneous to allow statistical pooling for a meta-analysis. Prevalent methodological limitations included a lack of clarity regarding concealment of randomized treatment allocation, no reporting of co-interventions, and no reporting of an intention-to-treat analysis. The more recent studies had greater limitations.

  • More recently, a meta-analysis examined the efficacy of epidural steroid injections in patients with sciatica [Pinto et al. 2012, also see discussion in UPDATE here]. Twenty-three placebo-controlled trials were included and there was a negligible but statistically significant pooled effect for treatment of leg pain over short-term follow-up; specifically, a 6-point difference on a 0-100 point pain scale. Even smaller, nonsignificant effects were found over the longer term. In these studies, the statistically significant outcomes did not reach thresholds for clinically meaningful effects.

Overall, Staal et al. conclude that the results of both reviews suggest that current best evidence is insufficient to support the use of injection therapy in patients with low-back pain or sciatica. Furthermore, they note that only a single international guideline on low-back pain, from Belgium, recommends injection therapy.

Guidelines from the U.S., Europe, Italy, and the UK do not recommend injection therapy for chronic low-back pain, Staal and colleagues assert. Instead, those documents variously recommend brief education about back pain, NSAIDs, opioid analgesics, back exercises, spinal manipulative therapy, multidisciplinary rehabilitation, behavioral therapy, and “back schools” (which combine education with many of the other modalities). The researchers write…

“Based on available literature, injection therapy for low-back pain and sciatica can be regarded as having limited clinical benefit. The reported guidelines indicate that clinicians currently have other more evidence-based and noninvasive treatment options at their disposal, such as NSAIDs in the acute phase and supervised exercise therapy and multidisciplinary rehabilitation in the chronic phase.”

Still, Staal et al. concede that patients with low-back pain may differ in their clinical presentation and respond differently to treatments. “Injection therapy of any kind may be beneficial in individual cases or subgroups,” they state. Despite this, given the weak scientific evidence base and the availability of noninvasive and at least equally effective alternatives, the researchers affirm that “physicians and policy makers should not recommend the use of injection therapy for patients with low-back pain and sciatica.”

COMMENTARY: This “Viewpoint” article in JAMA is merely the latest salvo fired against interventional injection procedures for back pain. Certainly, there may be differences of opinion, but the preponderance of accumulated evidence — some of good quality, but much of it less so — appears to be balanced against injection therapies for chronic back pain conditions. We have discussed many of the concerns and associated research in a prior series of Pain-Topics UPDATES [click here].

In fair balance, we must note that the American Society of Interventional Pain Physicians (ASIPP) recently released its 2013 Guidelines for Interventional Techniques in Chronic Spinal Pain, 7th Update [see Manchikanti, Abdi, et al. 2013; Manchikanti, Falco, et al. 2013]. Development of the voluminous documents (283 pages) involved a multidisciplinary panel of experts in various fields, who reviewed the evidence and formulated recommendations for interventional techniques in managing chronic spinal pain.

The ASIPP guidelines note that from 2000 to 2011 there was a 228% increase in interventional procedures performed in the United States. Overall, evidence was determined to be fair-to-good in favoring 62% of the diagnostic interventions and 52% of the therapeutic interventions assessed. The strength of evidence grading system was derived from methods advocated by the U.S. Preventive Services Task Force and merely assigns rankings of poor, fair, or good. Findings in the ASIPP documents suggest that considerable proportions of interventions for spinal pain are unsupported by evidence of any adequate quality.

In a quick reading of the ASIPP guidelines it becomes apparent that there is a large and heterogenous collection of procedures used by interventionists, a majority involving injections of one sort or another. The evidence for each must be considered on its own merits; so, it could be unfair to claim, for example, that all injections are unsupported by evidence and of little value, since select procedures in properly qualified patients might be of some benefit.

Epidural InjectionAs for the value of injection therapy for low-back pain or sciatica, which are of most concern to Staal and colleagues above, the ASIPP guidelines include extensive and detailed discussions of the evidence. However, the meticulous descriptions are complicated and somewhat confusing due to separate consideration of the many procedural techniques — eg, transforaminal vs interlaminar vs caudal in the case of epidural injections — the solutions used, and the numerous pathologies addressed. Generally, evidentiary support for epidural injection procedures as a whole seems equivocal or weak and the discussions of adverse effects in the guidelines seem vague or inadequate in many cases. There are no clear summary statements comparing and contrasting risks versus benefits for each type of injection procedure.

The ASIPP guidelines are probably the most comprehensive and detailed examinations of interventional procedures available from any source. Clearly, they appear to be created largely by and for interventionists and may reflect biases of the reviewers who were selected to develop the documents. The findings are probably unlikely to alter interventional practices, but they might encourage practitioners in more careful patient selection and better education of patients for making informed decisions.

What is most urgently needed is an unbiased, ruthlessly objective, and fair-balanced summary of the evidence surrounding interventional injection therapies — accounting for short- and long-term risks versus benefits — that nonspecialist healthcare providers and their patients can grasp and act upon. The ASIPP guidelines might provide a basis for this, but much effort would be required in translating the findings into more clearly stated evidence-based recommendations.

In sum, despite the generally weak evidence of benefits and the potential for substantial risks, injection procedures are unlikely to diminish in numbers. Many advocates who are eschewing long-term pharmacotherapy, primarily opioids, for chronic spinal pain conditions are stressing the importance of nondrug treatments, and interventional procedures like epidural injections are a frequently-mentioned alternative.

In actuality, this may in some cases be motivated less by medical science and more by the fact that injections are not associated with substance misuse or abuse — but this is wrongheaded thinking in many respects. While interventional injection procedures may have a role in effective pain management, there is a need for better evidence and its assessment to determine those practices that are most helpful and safe in serving the needs of individual patients with pain.

REFERENCES:
> Manchikanti L, Abdi S, Atluri S, et al. An Update of Comprehensive Evidence-Based Guidelines for Interventional Techniques in Chronic Spinal Pain. Part II: Guidance and Recommendations. Pain Physician. 2013;16(2S);S49-S283 [
free access here].
> Manchikanti L, Falco FJE, Singh V, et al. An Update of Comprehensive Evidence-Based Guidelines for Interventional Techniques in Chronic Spinal Pain. Part I: Introduction and General Considerations. Pain Physician. 2013;16 (2S):S1-S48 [
free access here].
> Pinto RZ, Maher CG, Ferreira ML, et al. Epidural corticosteroid injections in the management of sciatica: a systematic review and meta-analysis. Ann Intern Med. 2012;157(12):865-877 [
abstract here].
> Staal JB, de Bie R, de Vet HC, et al. Injection therapy for subacute and chronic low-back pain. Cochrane Database Syst Rev. 2008;(3):CD001824 [
abstract here].
> Staal JB, Nelemans PJ, de Bie RA. Spinal Injection Therapy for Low Back Pain. JAMA. 2013 (May 16) online ahead of print [
article here].

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