Revision surgery and mortality following complex spine surgery: 2-year follow-up in a prospective cohort of 679 patients using the Spine AdVerse Event Severity (SAVES) system.

STUDY DESIGN: Prospective study. OBJECTIVE: To determine the 2-year risk of revision surgery and all-cause mortality after complex spine surgery, and to assess if prospectively registered adverse events (AE) could predict either outcome. Revision surgery and mortality are serious complications to spine surgery. Previous studies of frequency have mainly been retrospective and few studies have employed competing risk survival analyses. In addition, assessment of predictors has focused on preoperative patient characteristics. The effect of perioperative AEs on revision and all-cause mortality risks are not fully understood. METHODS: Between January 1 and December 31, 2013, we prospectively included all patients undergoing complex spine surgery at a single, tertiary institution. Complex spine surgery was defined as conditions deemed too complicated for surgery at a secondary institute, or patients with severe comorbidities requiring multidisciplinary observation and treatment. AEs were registered using the Spine Adverse Event Severity system and patients were followed for minimum 2 years regarding revision surgery and all-cause mortality. Incidences were estimated using competing risk survival analyses and correlation between AEs and either outcome was assessed using proportional odds models. RESULTS: We included a complete and consecutive cohort of 679 adult and pediatric patients. Demographics, surgical data, AEs, and events of revision or all-cause mortality were registered. The cumulative incidence of 2-year all-cause revision was 19% (16-22%) and all-cause mortality was 15% (12-18%). Deformity surgery was the surgical category with highest incidence of revision and the highest incidence of all-cause mortality was seen in the tumor group. Across surgical categories, cumulative incidences of 2-year revision ranged between 11% (tumor) and 33% (deformity), whilst 2-year all-cause mortality ranged between 3% (deformity) and 33% (tumor). We found that major intraoperative AEs were associated to increased odds of revision. Deep wound infection was associated to increased odds of all-cause mortality. CONCLUSIONS: We report the cumulative incidences of revision surgery and all-cause mortality following complex spine surgery. We found higher incidences of revision compared to previous retrospective studies. Prospectively registered AEs were correlated to increased odds of revision surgery and all-cause mortality. These results may serve as reference for future interventional studies and aid in identifying at-risk patients. LEVEL OF EVIDENCE: I.

Readmission following complex spine surgery in a prospective cohort of 679 patients - 2-years follow-up using the Spine AdVerse Event Severity (SAVES) system.

BACKGROUND CONTEXT: Recent studies suggest that prospective registration more accurately reflects the true incidence of adverse events (AEs). To our knowledge, no previous study has investigated prospectively registered AEs' influence on hospital readmission following spine surgery. PURPOSE: To determine the frequency and type of unplanned readmissions after complex spine surgery, and to investigate if prospectively registered AEs can predict readmissions. DESIGN: This is a prospective, consecutive cohort study. PATIENT SAMPLE: We conducted a single-center study of 679 consecutive patients who underwent complex spine surgery defined as conditions deemed too complicated for surgery at a secondary institute, or patients with severe comorbidities requiring multidisciplinary observation and treatment. OUTCOME MEASURES: The outcomes in this study were (1) readmission to any hospital department within 30 days of discharge and (2) readmission to a surgical spine center at any time in follow-up. METHODS: All patients undergoing complex spine surgery, at our tertiary referral center, were consecutively, and prospectively, included from January 1 to December 31, 2013. Demographics and perioperative AEs were registered using the Spine AdVerse Events Severity (SAVES) system. Patients were followed for a minimum of two years. A competing risk survival model was used to estimate rates of readmissions with death as a competing risk. Patient characteristics, surgical parameters and perioperative AEs were analyzed to identify factors associated with readmission. Analyses of 30-day readmission were performed using logistic regression models. A proportional odds model, with death as competing risk, was used for readmissions to a spine center at any time in follow-up. Results were reported as odds ratios with 95% confidence intervals (95% CI). RESULTS: Within 2 years of index discharge, 443 (65%) were readmitted. Only 20% of readmissions were to a spine center. Cumulative incidence (95% CI) of readmission was estimated to 13% (10%-16%) at 30 days, 26% (23%-30%) at 90 days, 50% (46%-54%) at 1 year, and 59% (55%-63%) at 2 years following discharge. Rates were markedly lower for readmissions to a spine center. Increased odds of 30-day readmission were correlated to intraoperative hypotension (p=.02) and major intraoperative blood loss (p<.01). Readmission to a spine center was associated with the number of instrumented vertebrae (p=.047), major intraoperative AE (p=.01), and intraoperative hypotension (p<.01). CONCLUSIONS: To the best of our knowledge, this is the first study to analyze prospectively registered AEs' association to readmission up to 2 years after complex spine surgery. We found that readmissions were more frequent than previously reported when including readmissions to any department or hospital. Factors related to major intraoperative blood loss were associated to increased odds of readmission. This should be considered during planning of postoperative observation and care.