After Posterior Fusions for Adult Spinal Deformity, Operative Time Is More Predictive of Perioperative Morbidity, Rather Than Surgical Invasiveness

A Need for Speed?

Andre M. Samuel, BBA; Michael C. Fu, MD; Nidharshan S. Anandasivam, BS; Matthew L. Webb, AB; Adam M. Lukasiewicz, MSc; Han Jo Kim, MD; Jonathan N. Grauer, MD

Disclosures

Spine. 2017;42(24):1880-1887. 

In This Article

Abstract and Introduction

Abstract

Study Design. A retrospective cohort study.

Objective. The aim of this study was to determine the independent effects of operative time and surgical invasiveness on perioperative outcomes after posterior spinal fusions for adult spinal deformity.

Summary of Background Data. Morbidity is high after posterior fusions for adult spinal deformity. Although previous reports have demonstrated an association between perioperative outcomes and the extent of correction and fusion (number of posterior levels fused, pelvic fixation, combined anterior-posterior fusion), no study has looked at the independent effects of the surgical invasiveness after controlling for operative time.

Methods. All adult patients, undergoing posterior spinal fusion for spinal deformity, were identified in the 2010 to 2014 National Surgical Quality Improvement Program (NSQIP) database. Multivariate analysis was used to determine the independent effects of longer operative timing and the surgical invasiveness (number of levels fused, anterior or transforaminal interbody fusions, osteotomies, and pelvic fixation) on 30-day complications.

Results. A total of 1540 patients undergoing posterior spinal fusion for adult spinal deformity were identified. The overall rate of complications was 15.3%. In multivariate analysis, greater operative timing was associated with increased inpatient complications [odds ratio (95% confidence interval, 95% CI) from 2.23 (1.25–3.98) for 7–8 hours to 4.46 (2.61–7.64) for 9+ hours; P < 0.001]. Although the number of levels fused, anterior/interbody fusions, osteotomies, and pelvic fixation were associated with complications on bivariate analysis, these factors were not associated with increased complications in multivariate analysis when controlling for other factors such as operative time.

Conclusion. For adult deformity surgery, longer operative time appears to be a better predictor of the overall rate perioperative complications than surgical invasiveness in multivariate analysis. Rather than avoidance of a more extensive and invasive surgical procedure, which may be indicated to improve alignment and stability, these data suggest the importance of safely and efficiently minimizing overall operative time.

Level of Evidence: 4

Introduction

Adult spinal deformity (ASD) is relatively common in the adult population, with previous reports estimating that there are over 500,000 adults with curves over 30° in the United States.[1,2] Posterior spinal fusion is commonly performed to correct these deformities.[3] Operative correction of ASD has good reported outcomes, improving Scoliosis Research Society-22 (SRS-22) and Oswestry Disability Index (ODI) outcome measures, and reducing back and leg pain, compared with nonoperative therapy.[4–6] Combining these procedures with anterior column support, pelvic fixation, and osteotomies have been shown to improve construct alignment and stability, and thus improve long-term outcomes.[7–9]

However, even with modern surgical techniques, instrumentation systems, intraoperative monitoring, and postoperative care, the rate of complications is high after these procedures.[7,10–13] Perioperative mortality (within 30 postoperative days) has been reported at 2.4%.[14] The rate of venous thromboembolism is as high as 13.6%.[15] In the population of patient aged 60 years or older, the overall rate of perioperative complications after ASD surgery has been reported to be 37.0%.[16] In addition, the occurrence of postoperative complications has been shown to slow the recovery process and also lead to worse long-term outcomes.[6,17,18]

Previous analyses of risk factors for complications after ASD correction have demonstrated that an increased scope of surgery is associated with increased complications. In the largest previous study of ASD correction by Worley et al.,[11] it was found that in 11,982 patients, the number of vertebral levels fused was predictive of morbidity. However, the multivariate analysis in this study failed to control for overall operative time, which may be a confounding factor. Similarly, Pugely et al.[19] studied 2005 pediatric patients undergoing spinal deformity correction. In this population, anterior interbody fusions and pelvic fixations were found to be associated with complications in bivariate analysis, but interestingly these factors did not remain significant in multivariate analysis that controlled for factors such as operative time. It thus hypothesized that the negative association of surgical invasiveness on perioperative outcomes (which may be needed to achieve adequate stability, alignment, and thus long-term outcomes[4,7–9]) may have been overestimated in prior studies on ASD that have not taken operative time into account.

The current study will leverage the National Surgical Quality Improvement Program (NSQIP) database, admission years 2010 to 2014, to characterize 30-day complications after posterior spinal fusions for ASD. The large sample size afforded by the database will then allow for multivariate analysis of the independent effects of both operative time and surgical invasiveness (number of levels fused, anterior or transforaminal interbody fusions, osteotomies, and pelvic fixation) on perioperative complications.

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