111. Risk factors for ambulatory surgery conversion to extended stay among patients undergoing one- or two-level posterior lumbar decompression

Abstract

<h3>BACKGROUND CONTEXT</h3> Ambulatory surgery (AMS), or outpatient surgery, is increasingly common for patients with lumbar spine disease. Previous reports suggest AMS is associated with lower cost and similar quality of care compared to conventional inpatient spine surgery. Under the current Center for Medicare and Medicaid services (CMS) two-midnight rule, a prolonged stay beyond 48 hours is considered an inpatient admission. AMS patients may unintentionally be subjected to extended hospital stays, which can lead to higher medical costs. An unanticipated extension of hospitalization can be a great burden not only to patients, but to medical providers and insurance companies. However, little is known about the risk factors for AMS conversion to extended stay. <h3>PURPOSE</h3> To investigate the factors associated with the conversion of patient status from ambulatory surgery (outpatient) to observation stay (OS) (less than 48 hours) or inpatient (greater than 48 hours). <h3>STUDY DESIGN/SETTING</h3> Retrospective study. <h3>PATIENT SAMPLE</h3> This study included 1,096 adult patients undergoing one- or two-level lumbar decompression surgery at a single academic institution from January 1, 2019 to March 16, 2020. <h3>OUTCOME MEASURES</h3> Conversion rate and risk factors from AMS to OS or inpatient. <h3>METHODS</h3> Ethical board approval was obtained for this study. The records of patients who underwent one- or two-level lumbar decompression surgery planned for AMS were retropectively reviewed. Patients were categorized in three groups based on length of stay that consisted of AMS, OS (less than 48-hour stay), and inpatient (staying greater than 48 hours). Data on patient demographics, medical co-morbidities, surgical information including intraoperative complications and postsurgical pain scores, and administrative information such as operation start time were collected. Simple and multivariable logistic regression analyses were conducted comparing AMS patients and OS/inpatient. Statistical signicance was defined as p <0.05. <h3>RESULTS</h3> Of the 1,096 patients, 641 (58%) patients were converted to either OS (486, 44%) or inpatinet (155, 14%) status. The multivariable analysis demonstrated that age (>80 years old), high ASA grade, history of sleep apnea, drain use, high estimated blood loss, long operation, laminectomy for spinal stenosis, late operation start time, and a high pain score in the acute care unit were considered independent risk factors for AMS conversion to OS/inpatient status. <h3>CONCLUSIONS</h3> Our results indicated that several surgical factors along with patient factors are significantly associated with AMS conversion. Addressing modifiable surgical factors, such as blood loss and operation start time and postoperative pain management might reduce the AMS conversion rate and be beneficial to patients and facilities. <h3>FDA DEVICE/DRUG STATUS</h3> This abstract does not discuss or include any applicable devices or drugs.