An estimated 50% of patients scheduled to undergo surgical correction of their adult spinal deformity (ASD) are preoperatively managed with chronic opioid therapy. In recent years, preoperative opioid use has been correlated with increased morbidity and mortality following major abdominal, orthopaedic, and spine surgery. Despite high prevalence of chronic opioid consumption in ASD population, limited data is available to guide preoperative opoid tapering to improve postoperatve outcomes. First attempt to identify a morphine equianalgesic (MEA) dose threshold for patients undergoing spine procedures was described in Neurosurgery by Wick and co-workers. After calculating MEA values for 1020 cervical and lumbar spine surgical patients, the group reported MEA dose threshold beyond which patients are less likely to achieve the minimum clinically important difference (MCID). In patients undering a Complex Spine Surgical procedure, we hypothesize that an increased preoperative opioid dose may have a threshold beyond which patients are more likely to suffer from an adverse event. A trained data abstractor will collect data for the analysis during the retrospective chart review. In addition to data collection, abstractor will calculate morphine equivalent dose (MED) values for each patient meeting the inclusion criteria. Statistical analysis will be performed to evaluate association between MED values and postoperative outcomes. Parametic and non-parametic tests will be used as necessary, inclusing but not limited to t-tests for Equality of Means, Fishcer exact test, Chi-square, Independent Samples Mann-Whitney U Test, and logisitic regression. All data will be reported in aggregate. Reporting a defined opioid theshold for ASD patients may aid in developing a standardized tapering protocol aimed at improving postoperative outcomes.