Cost effectiveness of periradicular infiltration for sciatica: subgroup analysis of a randomized controlled trial

A subgroup analysis of a prospective, randomized controlled trial was performed.

To describe the cost effectiveness of periradicular infiltration with steroid in subgroups of patients with sciatica.

A recent trial on periradicular infiltration indicated that a methylprednisolone-bupivacaine combination had a short-term effect, as compared with that of saline. This report describes the efficacy and cost effectiveness of steroid in subgroups of patients with sciatic.

This study involved 160 patients with unilateral sciatica. Outcome assessments were leg pain (100-mm visual analog scale), disability on the Oswestry Low Back Disability Questionnaire, and the Nottingham Health Profile. Data on medical costs and sick leaves also were gathered. Patients were randomized for periradicular infiltration with either methylprednisolone-bupivacaine or saline. The adjusted between-group treatment differences at each follow-up assessment, the number of patients free of leg pain (responders, cutoff 75%), and efficacy by the area-under-the-curve method were calculated. For the cost-effectiveness estimate, the total costs were divided by the number of responders. The rate of operations in different subgroups was evaluated by Kaplan-Meier analysis.

In the case of contained herniations, the steroid injection produced significant treatment effects and short-term efficacy in leg pain and in Nottingham Health Profile emotional reactions. For symptomatic lesions at L3-L4-L5, steroid was superior to saline for leg pain, disability, and straight leg raising in the short term. By 1 year, steroid seemed to have prevented operations for contained herniations, costing $12,666 less per responder in the steroid group (P < 0.01). For extrusions, steroid seemed to increase the operation rate, and the steroid infiltration was more expensive, costing $4445 per responder (P < 0.01).

In addition to short-term effectiveness for contained herniations and lesions at L3-L4-L5, steroid treatment also prevented surgery for contained herniations. However, steroid was countereffective for extrusions. The results of the subgroup analyses call for a verification study.