Six prospective randomised trials (n=505) were included in the review: one triple-blind, four double-blind and one single-blinded. Sample sizes ranged from 23 to 160 patients. Follow-up durations were variable.
Three of four efficacy studies reported as being of high quality indicated some short term benefit (two to six weeks) in pain reduction after epidural steroid injection. However, the treatment differences were reported to be small and no differences were reported at either three and six months (two studies) or after one year (two studies). Studies reported conflicting results on whether epidural steroid injections resulted in less surgery, with the authors reporting no benefit in the better designed studies.
Complications were reported in the review, but those results also included studies not meeting the inclusion criteria.