Epidural injections for spinal pain: a systematic review and meta-analysis evaluating the "control" injections in randomized controlled trials.

BACKGROUND Epidural steroid injection is the most frequently performed pain procedure. This study of epidural steroid "control" injections aimed to determine whether epidural nonsteroid injections constitute a treatment or true placebo in comparison with nonepidural injections for back and neck pain treatment. METHODS This systematic review with direct and indirect meta-analyses used PubMed and EMBASE searches from inception through October 2012 without language restrictions. Study selection included randomized controlled trials with a treatment group receiving epidural injections of corticosteroids or another analgesic and study control groups receiving either an epidural injection devoid of treatment drug or a nonepidural injection. Two reviewers independently extracted data including short-term (up to 12 weeks) pain scores and pain outcomes. All reviewers evaluated studies for eligibility and quality. RESULTS A total of 3,641 patients from 43 studies were included in this systematic review and meta-analysis. Indirect comparisons suggested epidural nonsteroid were more likely than nonepidural injections to achieve positive outcomes (risk ratio, 2.17; 95% CI, 1.87-2.53) and provide greater pain score reduction (mean difference, -0.15; 95% CI, -0.55 to 0.25). In the very limited direct comparisons, no significant differences were noted between epidural nonsteroid and nonepidural injections for either outcome (risk ratio [95% CI], 1.05 [0.88-1.25]; mean difference [95% CI], 0.22 [-0.50 to 0.94]). CONCLUSION Epidural nonsteroid injections may provide improved benefit compared with nonepidural injections on some measures, though few, low-quality studies directly compared controlled treatments, and only short-term outcomes (≤12 weeks) were examined.