This review concluded that there was limited evidence for blind interlaminar epidurals in pain management from chronic low back pain except for short-term pain relief from disc herniation and radiculitis. Although cautious, these conclusions may be doubtful due to limitations in the literature search and presentation of study results.

To evaluate the effects of lumbar interlaminar epidural injections for managing chronic low back and lower extremity pain.

PubMed and EMBASE were searched from 1966 to November 2008. Other databases and reference lists of existing reviews were searched. Search terms were partially reported and only studies published in English were included.

Randomised controlled trials (RCTs), observational studies and reports of complications in patients diagnosed with chronic low back pain for at least three months were eligible for inclusion. Observational studies were included only if there were fewer than four RCTs in a particular category. The intervention of interest was lumbar interlaminar epidural injections with or without steroids given for low back pain or lower extremity pain secondary to lumbar disc herniations and radiculitis, spinal stenosis and low back pain of discogenic origin without radiculitis or disc herniation. Outcomes of interest were documented pain relief, functional assessment, psychological improvement, return to work and opioid intake. Studies had to provide appropriate management, assess outcomes at six months and report a statistical evaluation.

Included RCTs were of patients with disc herniation, sciatica or spinal stenosis; one included patients with acute herniation nucleus pulposus or spinal stenosis of longer than six months. None of the interventions were performed under fluoroscopy. Epidural injections were 80mg of methylprednisolone or triamcinolone with or without bupivacaine compared with either an identical injection given intramuscularly or a saline placebo injection. Outcomes were assessed at various times from one day to 24 months. The observational study assessed an epidural steroid injection given once weekly for three weeks with outcomes assessed for 24 months.

The authors did not state how many reviewers performed the study selection.

Study validity was assessed using criteria of Cochrane Collaboration for RCTs and Agency for Healthcare Research and Quality (AHRQ) for observational studies. RCT assessment covered study population, interventions, blinding, relevant outcome measures, intention-to-treat analyses and adequate length of follow-up. AHRQ criteria covered study question, population, patient comparability, exposure or intervention, outcome measures, statistical analysis, results, discussion and funding source. Each item was weighted and a total score calculated. Only studies that scored over 50 on the 100-point scale were included in the analysis. Studies were assessed for clinical relevance and graded using levels of evidence.

Validity was assessed by two physicians. Disagreements were resolved by referral to a third person.

Outcomes for pain relief were extracted for less than three months, three months, six months and 12 months. Short-term relief was classed as six months or less and long-term relief was more than six months. RCTs were classed as positive if the epidural injection showed a statistically significant difference compared to control for the primary outcome measure and negative if there was no difference or no improvement from baseline. Observational studies were positive if injection therapy was effective in showing a positive outcome.

The authors did not state how many reviewers performed data extraction.

Results were reported in a narrative synthesis grouped by condition: disc herniation and/or radiculopathy; discogenic/low back pain; and spinal stenosis.

Five RCTs (n=635) and two observational studies (n=316) were included in the evidence synthesis (although six RCTs were included in the validity assessment). Quality scores for RCTs ranged from 60 to 86. Observational studies scored 53 and 75.

Disc herniation and radiculitis (five RCTs): One study showed positive short-term relief with an improvement in nerve root symptoms for the first five weeks after epidural injection, but no long-term effectiveness. Another study showed significant improvement in leg pain for the epidural injection group after six weeks, but no long-term effectiveness. The other three studies showed no short- or long-term benefits with epidural injection.

Spinal stenosis (two RCTs and one observational study): One study showed positive short-term relief with an improvement in nerve root symptoms for the first five weeks after epidural injection, but no long-term effectiveness. The other two studies found no short- or long-term benefits with epidural injection.

Low back pain of discogenic origin: One observational study evaluated epidural steroid injections in 232 patients with degenerative disc disease with or without inflammatory endplate changes. This found short-term improvements in pain and function, but had a very high dropout rate (60% of patients over two years).

Two studies were included for cost-effectiveness. Both concluded that interlaminar epidural steroid injections were not cost-effective.

There was limited evidence for effectiveness of blind interlaminar epidurals in management of all types of pain, except for short-term pain relief from disc herniation and radiculitis. The evidence did not represent contemporary pain management practices and could not be extrapolated to injections directed by fluoroscopy.

This review stated inclusion criteria for study design, interventions, participants and outcomes. The search was fairly small and included only studies that were published in English, which meant that some relevant studies may have been missed. Assessment of study validity was thorough and only studies that satisfied a certain level were discussed further in the review. However, reliance on an overall score, even one that was weighted, had limitations. Reporting of the methods of conducting validity assessment were thorough; it was not reported whether study selection and data extraction were also performed in duplicate to reduce the risk of errors. Presentation of the results as a narrative appeared appropriate, but there was a lack of numerical results; reporting results as positive or negative was not helpful without supporting data. Due to limitations with the literature search and presentation of results, the reliability of the author's conclusions, although cautious, may be in doubt.

The authors did not state any implications for practice or research.

Not stated.

This is a critical abstract of a systematic review that meets the criteria for inclusion on DARE. Each critical abstract contains a brief summary of the review methods, results and conclusions followed by a detailed critical assessment on the reliability of the review and the conclusions drawn.