INTRODUCTION:Despite numerous advancements in spinal surgery, the incidence of adverse events (AEs) is still high and clinically relevant. The goal of this study is the use of a validated capture system (Spinal Adverse Events Severity system, SAVES V2) to collect complications and to identify risk factors related to occurrence of complications and factors influencing length of stay (LOS).
METHODS: We retrospectively collected AEs occurring in a tertiary referral centre for spine surgery from January 2017 to January 2018. Patients characteristics including sex, age, comorbidities (Charlson Comorbidity Index), ASA score and prior exposure to spinal surgery, the type and setting (emergency or elective) of the surgical procedure were collected. The LOS during the index admission was calculated for each patient. Univariate and multivariate logistic regression models were used to determined odds ratio (ORs) for selected potential risk factors of AEs and prolonged LOS.
RESULTS: from January 2017 to January 2018 a total of 336 patients underwent spinal surgery (223 non-oncological and 113 oncological procedures). Intraoperative complications were more frequent in the oncological group (23 AEs/113) than in the non-oncological group (7 AEs/223). Early postoperative complications were predominant (66% of total AEs), with a higher incidence in the oncological group (46% vs. 38%). The rate of late post-operative complications was similar in the two groups (15% vs 11%).
In the non-oncological group, different factors (age >75 years old, anatomical region, surgical time > 3 hours, instrumentation, previous surgeries, type of surgery) were associated with complications but at multivariate analysis only surgical time > 3 hours was confirmed as risk factor (OR=5.0, 95% CI: 1.8-13.9). Surgical time > 3 hours and the presence of a post-operative complication were associated with increased LOS, however the presence of a post-operative complication was the only risk factor for increased LOS at multivariate analysis (OR=3.3 (95%CI:1.5-7.1)).In the oncological group, surgical time > 3 hours, instrumentation, previous surgery were factors associated with complications but only the presence of previous surgeries was confirmed as risk factor for complications at multivariate analysis factor. Surgical time > 3 hours and post-operative complications were confirmed as risk factors for prolonged LOS at multivariate analysis (respectively: OR=2.7 (95%CI:1.0-7.3), OR=3.5 (95%CI:1.3-9.3)).
Afterwards was analyzed the correlation between operative time and each type of intra-operative and post-operative AEs. In the oncological group 22 intraoperative complications occurred in a surgical time > 3 hours (40% dural tear). The “other” represented 43% of early AEs in the surgical time > 3 hours and also in the late post-op AEs 35%. In the non-oncological group were recorded 60/84 early post-operative AEs with surgical time > 3 hours (55% “other" category). In the late post-operative AEs 21/24 complications were part of surgical time >3 hours and “construct failure with loss of correction” represented 38% of complications.
DISCUSSION: Spine surgery has a relatively high incidence of complications that can lead to increased morbidity and mortality. Better categorization of complications and recognition of risk factors for complications and prolonged LOS are fundamental to improve patients' safety and clinical outcomes.