Concordant provocation as a prognostic indicator during interlaminar lumbosacral epidural steroid injections

Background: interlaminar epidural steroid injection is a well-established intervention for the treatment of radicular pain. pain is commonly reported during the injection into the epidural space; this provocation is typically either concordant or discordant with the patient's baseline pain. it is not well known how this provocation pain relates to treatment outcomes. objective: to determine the relationship between concordant versus discordant provocation during interlaminar epidural steroid injection and its effects on pain reduction at follow-up. study design: secondary analysis of a single center,prospective randomized double-blind study. methods: interlaminar epidural steroid injections under fluoroscopic guidance were performed on 48 patients with radicular lumbosacral pain. after injection with 80 mg methylprednisolone and 2 ml of normal saline at a single level,patients were asked to report if pain was provoked,and whether the pain was concordant or discordant with their baseline pain. the primary outcome measure was self-rated percentage of pain reduction from baseline at 2-week follow-up. secondary outcomes included improvement in activity level and decreased analgesic consumption. results: provocation was observed in 37 out of 48 patients (77%). this was further classified as concordant (22/37,60%) or discordant (15/37,40%) pain. the concordant group achieved a significant decrease in self-reported pain as compared to the discordant group at 2-week follow- up (61%,t = 2.45,p < 0.01). there were also significantly more patients in the concordant group who reported 75% pain reduction as compared to the discordant group (x = 6.44,df(1),p < 0.05). there were no significant differences between concordant and discordant groups in regard to improvements in activity level (x = 2.56) and decreased analgesic use (x = 3.28). limitations: the secondary analysis did not examine long-term outcomes. conclusions: the concordant group demonstrated significantly higher pain reduction as compared to the discordant group. there were no significant differences between the 2 groups in terms of improved function or reduced analgesic requirements. concordant provocation during interlaminar epidural injection may be a predictor of outcome.