Epidural Steroid Injections and the Risk of Osteoporosis in Lumbar Spondylosis Patients: A Nationwide Population-Based Cohort Study

Background: Epidural steroid injections (ESIs) involve the administration of steroids and local anesthetics into the spinal epidural space, and they are performed by inserting a needle between the ligamentum flavum and dura. This procedure is suitable for patients with lumbosacral radiculopathy secondary to disc herniation or postsurgical radicular pain. The relief period of the analgesic medications may be prolonged by > 6 weeks, resulting in nonsurgical management becoming a suitable option. However, the negative effect of ESIs on bone mineral density has been reported. Objectives: We aimed to clarify the association between ESIs and osteoporosis risk by analyzing a nationwide population database. Study Design: This study is a nationwide retrospective cohort study. Setting: Data on 1 million cases randomly selected from the 2000 Registry for Beneficiaries of the National Health Insurance Research Database (NHIRD) were collected. Methods: In total, 4,957 patients who were diagnosed with lumbar spondylosis and received ESIs between 2000 and 2013 were identified from the NHIRD. Subsequently, another 4,957 patients with lumbar spondylosis were randomly selected from the same database and frequency matched by age, gender, and index year with the patients who received ESIs. Results: The mean age of the patients were 50.3 +/- 17.1 years. The incident rates of osteoporosis in the ESI and non-ESI groups were 7.95 and 7.01 per 1,000 person-years, respectively. Osteoporosis risk was significantly higher in the ESI cohort than in the non-ESI cohort (absolute standardized hazard ratio = 1.23, 95% confidence interval = 1.05-1.45, P = 0.01). The risk factors for osteoporosis were old age, being female, and undergoing ESIs. Osteoporosis risk was significantly higher in the ESI cohort than in the non-ESI cohort in the male, lowest-urbanization-level (fourth level), other-occupations, and comorbidity-free subgroups. Limitations: The NHIRD did not provide information on osteoporosis-related scales, renal function, blood pressure, smoking habit, pulmonary function, daily activities, and dosage of injected steroids. Conclusions: For patients diagnosed with lumbar spondylosis, ESIs are associated with a high osteoporosis risk. Thus, this therapy should be recommended with caution, especially for patients with correlated risk factors (e.g., high risk of osteoporotic fracture, low socioeconomic status, and retired or unemployed status).