Relationship Between Socioeconomic Status and the Outcome of Lumbar Epidural Steroid Injections for Lumbar Radiculopathy.

Objective: The aim of the study was to investigate the relationship between socioeconomic status and pain reduction from epidural steroid injections for lumbar radiculopathy.

Methods: The retrospective cohort consisted of patients undergoing epidural steroid injection for lumbar radiculopathy ( n = 544). Numeric Pain Rating Scale was measured at baseline and 2 wks after epidural steroid injection. Socioeconomic status was estimated using median family income in patients' ZIP code. Linear and mixed models examined demographic and clinical differences in pain before and after injection and whether family income moderated the effect.

Results: Majority of patients were White (72.4%), female (56.4%), engaged in physical activity (68.2%), and underwent unilateral, transforaminal epidural steroid injection (86.0% and 92.1%, respectively). Non-White patients and those who did not engage in physical activity had higher baseline pain ( P < 0.05). Lower socioeconomic status was associated with higher baseline pain (β = 0.06 per $10,000, P = 0.01). Patients with lower socioeconomic status experienced larger improvement in pain after epidural steroid injection: -1.56 units for patients in the 10th percentile of family income versus -0.81 for 90th percentile. Being a current smoker was associated with higher pain (β = 0.76, P = 0.03) and engaging in structured physical activity with less pain (β = -0.07 P < 0.01).

Conclusions: Lower socioeconomic status was independently associated with higher pain alleviation after controlling for other potentially influential demographics. Modifiable lifestyle factors may be a target of potential intervention.