Risk Factors and Independent Predictors of 30-Day Readmission for Altered Mental Status After Elective Spine Surgery for Spine Deformity: A Single-Institutional Study of 1090 Patients

Background Altered mental status (AMS) has been associated with inferior surgical outcomes. The factors leading to AMS after spine surgery are unknown. The aim of this study is to determine the risk factors and independent predictors of 30-day readmission for AMS in patients with spine deformity after undergoing elective spine surgery. Methods The medical records of 1090 adult (≥18 years old) patients with spine deformity undergoing elective spine surgery at a major academic institution from 2005 to 2015 were reviewed. We identified 18 patients (1.65%) who had AMS as the primary driver for 30-day readmission after surgery. Patient demographics, comorbidities, and intraoperative and postoperative complication rates were collected for each patient. The primary outcome investigated in this study was risk factors associated with 30-day readmission for AMS. Results Patient demographics and comorbidities were similar between both groups, with the AMS cohort being significantly older than the no-AMS cohort (70.11 vs. 61.93; P = 0.003). There were no significant differences in intraoperative variables and complication rates within the cohorts. The AMS cohort had a significantly higher proportion of patients transferred to the intensive care unit (AMS, 61.11% vs. no-AMS, 19.76%; P = 0.0002) and rate of pulmonary embolism (AMS, 11.11 vs. no-AMS, 0.93; P = 0.02) after surgery. Other postoperative complication rates were similar between the cohorts. In a multivariate stepwise regression analysis, age (P = 0.013) and ICU transfer (P = 0.0002) were independent predictors of 30-day readmission for AMS. Conclusions Our study suggests that increasing age and intensice care unit transfer are independent predictors of 30-day readmission for AMS after spine surgery in patients with spine deformity.