Neuroaxial Anesthesia Does Not Increase the Risk of Postoperative Low Back Pain after Herniorrhaphy

Background: Backache is a common complaint after spinal or epidural anesthesia. The causal relationship between anesthesia and postoperative low back pain is still debated. The aim of this investigation is to explore the association between neuroaxial anesthesia and post-operative low back pain in adult patients receiving herniorrhaphy by analyzing the National Health Insurance Research Database (NHIRD). Methods: The study is a retrospective cohort study. We analyzed the Longitudinal Health Insurance Database (LHID) which contains all the original claim data of 1,000,000 beneficiaries randomly sampled from all beneficiaries of Taiwan's NHIRD over the period 1998 to 2006. We screened all adult patients (older than 18 year old) who received epidural anesthesia or spinal anesthesia for inguinal herniorrhaphy or femoral herniorrhaphy as the study cohort. These patients were followed up to 1 year after surgery by the diagnosis of low back pain (defined by ICD-9-CM codes 720 to 724, exclude cervical and thoracic region). The comparison cohort was adult patients who received non-neuroaxial anesthesia for herniorrhaphy. Results: Total 5,457 adult patients received herniorrhaphy were screened from NHIRD, in which 4,455 patients received neuroaxial anesthesia and the other 1,002 patients didn't. During the one-year follow-up period, 161 (3.61%) of the neuroaxial anesthesia group and 37 (3.69%) of the control group developed acute low back pain. 387(8.69%) of the neuroaxial anesthesia group and 89(8.88%) of the control group developed chronic low back pain. The patients received neuroaxial anesthesia didn't increase their risk in developing postoperative acute (OR=0.943, 95% CI, 0.647-1.374) and chronic low back pain (OR=0.937, 95% CI, 0.729-1.203). Conclusions: To our knowledge, this is the first nationwide population-based study regarding the association of post-herniorrhaphy backache with neuroaxial anesthesia in Taiwan. Our data showed that neuroaxial anesthesia does not increase the risk of low back pain in adult patients after herniorrhaphy. History of low back pain increased the risk of developing low back pain after surgery.