P26. Less than 6 weeks between epidural steroid injections increases the risk of infection after lumbar decompression

BACKGROUND CONTEXT Lumbar radiculopathy has a high prevalence in the United States, causing disability in up to 5% of the population. For patients who are not considered surgical candidates or for those who are not ready for surgical interventions, lumbar epidural corticosteroid injections (LESI) can provide both diagnostic and therapeutic benefits. The number of LESI has increased exponentially, with more than 2 million performed annually. However, patients that receive a LESI may still require a surgical intervention. While potentially beneficial for symptomatic relief, the dampening of the immune and inflammatory pathways could lead to an increased risk of infection following lumbar decompressions. PURPOSE The aim of this study was to determine whether the time interval between LESI and lumbar decompression was associated with an increased rate of postoperative infection or revision surgery following lumbar decompression (LD). METHODS Subjects undergoing LD procedures were identified using the PearlDiver Database. Patients were identified using current procedure terminology and international classification of diseases codes. Only patients with degenerative etiologies of lumbar stenosis were included. Outcomes measured include 2-year revision rate and infection rates after lumbar decompression. Patients who underwent LESI were queried, and those who underwent LD procedures after LESI were identified and stratified based on the duration of time from the last LESI to the subsequent procedure utilizing stratum-specific likelihood ratio (SSLR) analysis. In our study, the optimal time groupings identified by the SSLR analysis were 0 to 6 weeks and 6 to 26 weeks for lumbar decompression. In addition, a control group of patients who underwent lumbar decompression without any history of LESI was analyzed. Univariate analysis was conducted on demographic characteristics, comorbidities, and postoperative complications using Pearson chi-square analysis. If a postoperative outcome was significant on univariate analysis (p <0.05), a multivariable analysis using logistic regression was conducted to adjust for other potential risk factors. In order to determine factors for adjustment, demographics and comorbidities with p-values of <0.2 were included in the multivariable analysis. RESULTS In total, 2,334 patients received LESI within 6 weeks prior to lumbar decompression and 8,446 patients received LESI within 6-26 weeks prior. In addition, 39,258 patients did not receive any LESI prior to decompression. Univariate analysis demonstrated that patients who received LESI within 6 weeks prior to decompression had an increased incidence of infection compared to those who received it within 6-26 weeks prior to surgery, and those who did not receive LESI at all (4.54%, 2.92%, 3.18%, respectively; p<0.001). Multivariable analysis confirmed that patients who received LESI within 6 weeks prior to surgery had an increased likelihood of infection (OR 1.481, p<0.001) compared to those who received it within 6-26 weeks (OR 1.082, p<0.001). CONCLUSIONS Our study demonstrates that patients receiving LESI within 6 weeks prior to surgery had an increased risk of infection compared to patients who received LESI within 6-26 weeks of surgery and patients who did not receive LESI. Interestingly, those who received LESI within 6-26 weeks of surgery had a lower risk of infection compared to those who did not receive LESI. Further research should be done to understand this temporal relationship between LESI and lumbar decompression. FDA Device/Drug Status This abstract does not discuss or include any applicable devices or drugs. Lumbar radiculopathy has a high prevalence in the United States, causing disability in up to 5% of the population. For patients who are not considered surgical candidates or for those who are not ready for surgical interventions, lumbar epidural corticosteroid injections (LESI) can provide both diagnostic and therapeutic benefits. The number of LESI has increased exponentially, with more than 2 million performed annually. However, patients that receive a LESI may still require a surgical intervention. While potentially beneficial for symptomatic relief, the dampening of the immune and inflammatory pathways could lead to an increased risk of infection following lumbar decompressions. The aim of this study was to determine whether the time interval between LESI and lumbar decompression was associated with an increased rate of postoperative infection or revision surgery following lumbar decompression (LD). Subjects undergoing LD procedures were identified using the PearlDiver Database. Patients were identified using current procedure terminology and international classification of diseases codes. Only patients with degenerative etiologies of lumbar stenosis were included. Outcomes measured include 2-year revision rate and infection rates after lumbar decompression. Patients who underwent LESI were queried, and those who underwent LD procedures after LESI were identified and stratified based on the duration of time from the last LESI to the subsequent procedure utilizing stratum-specific likelihood ratio (SSLR) analysis. In our study, the optimal time groupings identified by the SSLR analysis were 0 to 6 weeks and 6 to 26 weeks for lumbar decompression. In addition, a control group of patients who underwent lumbar decompression without any history of LESI was analyzed. Univariate analysis was conducted on demographic characteristics, comorbidities, and postoperative complications using Pearson chi-square analysis. If a postoperative outcome was significant on univariate analysis (p <0.05), a multivariable analysis using logistic regression was conducted to adjust for other potential risk factors. In order to determine factors for adjustment, demographics and comorbidities with p-values of <0.2 were included in the multivariable analysis. In total, 2,334 patients received LESI within 6 weeks prior to lumbar decompression and 8,446 patients received LESI within 6-26 weeks prior. In addition, 39,258 patients did not receive any LESI prior to decompression. Univariate analysis demonstrated that patients who received LESI within 6 weeks prior to decompression had an increased incidence of infection compared to those who received it within 6-26 weeks prior to surgery, and those who did not receive LESI at all (4.54%, 2.92%, 3.18%, respectively; p<0.001). Multivariable analysis confirmed that patients who received LESI within 6 weeks prior to surgery had an increased likelihood of infection (OR 1.481, p<0.001) compared to those who received it within 6-26 weeks (OR 1.082, p<0.001). Our study demonstrates that patients receiving LESI within 6 weeks prior to surgery had an increased risk of infection compared to patients who received LESI within 6-26 weeks of surgery and patients who did not receive LESI. Interestingly, those who received LESI within 6-26 weeks of surgery had a lower risk of infection compared to those who did not receive LESI. Further research should be done to understand this temporal relationship between LESI and lumbar decompression.