Risk factors for perioperative morbidity in spine surgeries of different complexities: a multivariate analysis of 1,009 consecutive patients

Abstract

Background context: There is a broad spectrum of complications during or after surgical procedures, with differing incidences reported in the published literature. Heterogeneity can be explained by the lack of an established evidence-based classification system for documentation and classification of complications in a standardized manner.

Purpose: The objective of this study was to identify predictive risk factors for perioperative and early postoperative morbidities in spine surgeries of different complexities in a large cohort of consecutive patients.

Study design: This study is a retrospective case series.

Outcome measures: The outcome measures are the occurrence of perioperative and early postoperative morbidities.

Methods: A classification of surgical complexity (Grades I-III) was created and applied to 1,009 patients who consecutively underwent spine surgery at a single university hospital. The incidence and the type of perioperative and early postoperative morbidities were documented. Multivariate binary logistic regression analyzed risk factors for (1) hospital stay of ≥10 days, (2) intermediate care unit (IMC) stay of ≥24 hours, (3) blood loss of >500 mL, and occurrence of a (4) surgical or (5) medical morbidity.

Results: A deviation from the regular postoperative course (defined as "morbidity") included surgical reasons, such as relapse of symptoms of any kind (3.3%), wound healing problems (2.4%), implant-associated complications (1.6%), postoperative neurologic deficits (1.5%), infection (1.5%), fracture (0.8%), and dural tear in need of revision (0.6%). Medical reasons included anemia (1.8%), symptomatic electrolyte derailment (1.0%), and cardiac complications (0.7%), among others. An independent risk factor associated with a surgical reason for an irregular postoperative course was male gender. Risk factors associated with a medical reason for an irregular postoperative course were identified as preoperatively high creatinine levels, higher blood loss, and systemic steroid use. Independent risk factors for a prolonged hospitalization were preoperatively high C-reactive protein level, prolonged postoperative IMC stay, and revision surgery. Spinal stabilization or fusion surgery, particularly if involving the lumbosacral spine, age, and length of surgery were associated with blood loss of >500 mL. Higher surgical complexity, involvement of the pelvis in instrumentation, American Society of Anesthesiologists Grade ≥III, and preoperatively higher creatinine levels were associated with a postoperative IMC stay of >24 hours.

Conclusions: The present study confirms several modifiable and non-modifiable risk factors for perioperative and early postoperative morbidities in spine surgery, among which surgical factors (such as complexity, revision surgery, and instrumentation, including the pelvis) play a crucial role. A classification of surgical complexity is proposed and validated.

Keywords: Blood loss; Classification; Complication; Hospital stay; Morbidity; Revision; Risk; Spine surgery.