P40. Reduced complications but no differences in readmissions with minimally invasive versus open posterior based lumbar interbody fusion, a national study

Abstract

<h3>BACKGROUND CONTEXT</h3> In single and multi-institution studies, minimally invasive (MIS) posterior and transforaminal lumbar interbody fusion (LIF) has been associated with decreased blood loss, length of stay, costs and improved short term functional outcomes. No national studies exist directly comparing MIS to traditional open posterior-based lumbar interbody fusion procedures. <h3>PURPOSE</h3> We aim to analyze the utilization of anterior MIS-LIF procedures and compare complications, readmissions and reoperations to open-LIF procedures. <h3>STUDY DESIGN/SETTING</h3> Retrospective, administrative databases. <h3>PATIENT SAMPLE</h3> National Inpatient Sample (NIS), National Readmissions Database (NRD), 2016 to 2019. <h3>OUTCOME MEASURES</h3> Readmissions, reoperations, mortality, index hospitalization complications, costs, length of stay, discharge destination. <h3>METHODS</h3> The NIS and NRD databases were queried from 2016 to 2019 to identify patients undergoing posterior-based one- or two-level LIF with a diagnosis of degenerative disc disease, spondylosis, spondylolysis and spondylolisthesis. MIS was defined as procedures utilizing percutaneous or endoscopic approaches. Multivariate regression was used to assess factors associated with procedure type, cost, LOS and discharge destination. Propensity score matching was used to compare index hospital complications, readmission and reoperations at 30, 90 and 180-day intervals. <h3>RESULTS</h3> A total 382,395 posterior-based LIF were estimated to have occurred in the US between 2016 and 2019, with 4,260 (1.1%) of those utilizing MIS techniques. The proportion of MIS procedures did not change significantly over the study period (p=0.40). Two-level procedures were identified in 27.8% and 29.4% of cases for MIS and open procedures, respectively (p=0.32). On multivariate modeling, patients receiving care in the western census regions were significantly less likely to undergo an MIS procedure (OR 0.38, p < 0.0001) relative to the midwest region, while patients receiving care in a medium sized hospital were more likely to receive an MIS procedure relative to a large hospital (OR 1.34, p=0.0003). Patients with a history of coagulopathy, cardiac arrhythmia and fluid & electrolyte disorders were significantly less likely to undergo MIS procedures. MIS procedures were associated with a decreased LOS of 0.69 days (p < 0.0001) and decreased rate of nonhome discharge (OR 0.71, p=0.003). Cost did not differ by procedure type (p=0.35). On matched analysis, MIS patients had a lower rate of overall complications (10.7 vs 14.6%, p < 0.001), neurologic complications (2.8 vs 5.2%, p < 0.001) and blood transfusion (1.7 vs 4.6%, p<0.001). In analysis of 30-day outcomes, there were no differences with regard to all cause readmission (3.5 vs 3.3%, p=0.74), related readmission (1.0 vs 1.5%, p=0.085), readmission for a specific related indication, repeat LIF or mortality. At 90 days, there were no differences in all cause readmission (6.5 vs 6.3%, p=0.81), related readmission (1.7 vs 2.5%, p=0.064), readmission for a specific related indication, repeat LIF or mortality. Finally, at 180-day analysis, there were no differences in all cause readmission (10.1 vs 9.4%, p=0.50), related readmission (2.1 vs 3.1%, p=0.076), readmission for a specific related indication, repeat LIF or mortality. <h3>CONCLUSIONS</h3> Utilization of posterior-based MIS LIF remains low nationally, with 1.1% of procedures utilizing these techniques between 2016 to 2019. MIS is associated with reduced hospital costs, length of stay and blood transfusions compared to open approaches. Short-term rates of readmission and reoperation were similar between MIS and open LIF. <h3>FDA DEVICE/DRUG STATUS</h3> This abstract does not discuss or include any applicable devices or drugs.