Negative affect and sleep disturbance may be associated with response to epidural steroid injections for spine-related pain

Objective: To describe whether negative affect and sleep impairment are associated with the clinical effect of epidural steroid injections (ESIs) for low back pain.

Design: Observational study; patients were evaluated before ESI and 1 and 3 months after ESI.

Setting: Spine center and related treatment sites.

Participants: Participants (N=158) seeking treatment for low back pain with or without radiculopathy.

Intervention: ESI for low back pain with or without radiculopathy.

Main outcome measures: We assessed the dependent (global pain severity for back and leg pain, pain behavior, pain interference) and independent variables (depression, sleep disturbance, and covariates of back pain response) with the Patient-Reported Outcome Measurement Information System (PROMIS) and legacy measures. Outcome was assessed cross-sectionally using multiple regression and longitudinally with path analysis.

Results: After 1 month, sleep disturbance was the only predictor for the global ratings of improvement in back pain (R(2)=16.8%) and leg pain (R(2)=11.4%). The proportions of variance explained by sleep disturbance and negative affect for all dependent variables were greater at 3 months than 1 month. Mediation analysis was significant for negative affect for the 3-month outcomes on PROMIS pain behavior (β=.87, P<.01) and pain interference (β=.37, P<.01). There was no evidence of mediation by sleep disturbance for any outcome.

Conclusions: Negative affect and sleep disturbance are associated with worse outcomes after ESI. Further research is needed to determine if treatment of negative affect and sleep disturbance prior to or concurrently with ESI will improve outcomes.