94. Cost analysis of primary single-level lumbar discectomies

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BACKGROUND CONTEXT Improving value in surgical care requires a detailed understanding of the true costs of surgical and operating room resources. PURPOSE In this study, we sought to identify predictors of health care costs and operating room resource use for patients undergoing initial single-level discectomies using a unique institutional cost dataset from the value driven outcomes (VDO) program developed by the University of Utah. STUDY DESIGN/SETTING A retrospective cost analysis of primary single-level lumbar discectomies. PATIENT SAMPLE A total of 622 patients undergoing initial single-level lumbar discectomy between January 2014 to April 2016 at the University of Utah Orthopaedic Center. OUTCOME MEASURES Health care costs, clinical length of stay, and operating room time. METHODS Univariate and multivariate generalized linear models (GLM) performed to identify predictors of health care costs, clinical length of stay (LOS, days) and operating room time (OR, minutes) using a unique costing tool. Modified park test procedure was implemented to determine GLM error distribution specifications and standard errors were clustered by provider. Cost outcomes were normalized using mean costs for a patient with normal body mass index (BMI) and a healthy American Society of Anesthesiologists (ASA) classification system. Average marginal effects in multivariate analysis were reported as percentage of normalized costs. RESULTS Advanced age, male gender, Hispanic, Black, unemployment, and being retired were significant positive predictors of costs in univariate analysis. Asian, Native American, outpatient procedures, and being a student were significant negative predictors of costs. Univariate analysis also showed that obesity, higher ASA class and insurance status were also positive and significant predictors of costs. In multivariate analysis, we found that obesity led to higher average marginal total direct (9%), total facility (15%), and facility OR costs (22%), as well as an average marginal effect of 24 more OR minutes per surgery. Conversely, being underweight was associated with lower average marginal total direct (-23%), total non-facility (-54%), total facility (-8%), facility OR costs (-15%), as well as lower clinical LOS (-.42 days), and 18 less OR minutes. While being overweight was not significantly associated with greater total direct costs, it was associated with higher total facility (8%), and facility OR costs (12%), with an average marginal effect of 11 more OR minutes per surgery. Age was associated with a longer LOS but not with OR costs in multivariate analysis. As expected, outpatient surgical costs, LOS and OR time were significantly lower than inpatient procedures. Patients with incapacitating disease ASA Class had the highest predicted OR time in GLM estimates with an average marginal effect of 28 minutes, while severe systematic disease was associated with greater total and nonfacility costs. In addition, Medicare patients had higher facility costs (14%) compared to privately insured patients. CONCLUSIONS Although many of our observed variables were significant predictors of costs in univariate analysis, multivariate GLM estimates showed that the main variables determining cost and operating room time and resource use were obesity (BMI), general health (ASA class), Medicare status and advanced age, and whether the surgery was an outpatient or inpatient procedure. FDA DEVICE/DRUG STATUS This abstract does not discuss or include any applicable devices or drugs.