Epidural steroid injections and fracture incidence among older individuals with radiculopathy

Abstract

Epidural steroid injections (ESIs) are a common and often effective treatment for radicular back pain. While oral glucocorticoids increase fracture incidence, little is known regarding fracture risk after ESI. This study investigated the incidence of fractures among individuals who received ESI and those who did not. We hypothesized that ESI exposure would be associated with an increased incidence of osteoporotic fracture and specifically vertebral fractures. Using 2005-2018 5% Medicare data, individuals with radicular pain who had ≥1 ESI and those who did not (non-ESI) were matched 1:10 by age, sex, and month of radicular pain diagnosis using exposure density sampling (EDS). Using a high-dimensional propensity score (HDPS) calculated based on the top 500 covariates across multiple data dimensions, ESI and non-ESI individuals were matched 1:1. Fractures were identified using validated ICD-9/10 diagnosis codes. Fracture incidence rate (IR) was calculated by group, and hazard ratios (HR) compared using Cox regression. 25 062 ESI patients and 221 735 non-ESI patients who met eligibility criteria were identified using EDS. Mean age was 76 years (74% female). Among ESI-treated individuals, there were 2296 fractures, IR 49.1 (95% CI: 47.2-51.2) per 1000 person years. For non-ESI individuals, there were 11 917 fractures, IR 35.2 (95% CI: 34.5-35.8). Individuals who received ESI had a greater hazard of fracture at typical osteoporotic sites, HR 1.39 (95% CI 1.33-1.46) by EDS and 1.32 (1.12-1.54) by HDPS, and greater hazard of vertebral fracture, 1.54 (1.45-1.64) by EDS and 1.69 (1.38-2.07) by HDPS. Patients who received greater cumulative ESI doses (≥3 in 1 year) had a higher risk of fractures within the first six months of follow-up. ESI exposure in older individuals is associated with an increased risk of fracture, suggesting there may be lasting detrimental skeletal effects of ESI. Further research into strategies to reduce fracture risk in this population is warranted.