Study design: A systematic review of randomized controlled trials (RCTs).
Objective: To determine if injection therapy is more effective than placebo or other treatments for patients with subacute or chronic low back pain.
Summary of background data: The effectiveness of injection therapy for low back pain is still debatable. Heterogeneity of target tissue, pharmacological agent, and dosage, generally found in RCTs, point to the need for clinically valid comparisons in a literature synthesis.
Methods: We updated the search of the earlier systematic review and searched the Cochrane Central Register of Controlled Trials, MEDLINE, and EMBASE databases up to March 2007 for relevant trials reported in English, French, German, Dutch, and Nordic languages. We also screened references from trials identified. RCTs on the effects of injection therapy involving epidural, facet, or local sites for subacute or chronic low back pain were included. Studies that compared the effects of intradiscal injections, prolotherapy, or ozone therapy with other treatments were excluded unless injection therapy with another pharmaceutical agent (no placebo treatment) was part of one of the treatment arms. Studies about injections in sacroiliac joints and studies evaluating the effects of epidural steroids for radicular pain were also excluded.
Results: Eighteen trials (1179 participants) were included in this review. The injection sites varied from epidural sites and facet joints (i.e. intra-articular injections, peri-articular injections and nerve blocks) to local sites (i.e. tender-and trigger points). The drugs that were studied consisted of corticosteroids, local anesthetics, and a variety of other drugs. The methodologic quality of the trials was limited with 10 of 18 trials rated as having a high methodologic quality. Statistical pooling was not possible because of clinical heterogeneity in the trials. Overall, the results indicated that there is no strong evidence for or against the use of any type of injection therapy.
Conclusion: 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 therapy.