Rates and reasons for reoperation within 30 and 90 days following cervical spine surgery: a retrospective cohort analysis of the Michigan Spine Surgery Improvement Collaborative (MSSIC) registry

Abstract

BACKGROUND CONTEXT

Reoperation following cervical spinal surgery negatively impacts patient outcomes and increases health care system burden. To date, most studies have evaluated reoperations within 30 days after spine surgery and have been limited in scope and focus. Evaluation within the 90-day period, however, allows a more comprehensive assessment of factors associated with reoperation.

PURPOSE

The purpose of this study is to assess the rates and reasons for reoperations after cervical spine surgery within 30 and 90 days.

DESIGN

We performed a retrospective analysis of a state-wide prospective, multi-center, spine-specific database of patients surgically treated for degenerative disease.

PATIENT SAMPLE

Patients 18 years of age or older who underwent cervical spine surgery for degenerative pathologies from February 2014 to May 2019. Operative criteria included all degenerative cervical spine procedures, including those with cervical fusions with contiguous extension down to T3.

OUTCOME MEASURES

We determined causes for reoperation and independent surgical and demographic risk factors impacting reoperation.

METHODS

Patient-specific and surgery-specific data was extracted from the registry using ICD-10-DM codes. Reoperations data was obtained through abstraction of medical records through 90 days. Univariate analysis was done using chi-square tests for categorical variables, t-tests for normally distributed variables, and Wilcoxon rank-sum tests for variables with skewed distributions. Odds ratios for return to the operating room (OR) were evaluated in multivariate analysis.

RESULTS

A total of 13,435 and 13,440 patients underwent cervical spine surgery and were included in the 30 and 90-day analysis, respectively. The overall reoperation rate was 1.24% and 3.30% within 30 and 90 days, respectively. Multivariate analysis showed within 30 days, procedures involving four or more levels, posterior only approach, and longer length of stay had increased odds of returning to the OR (p<.05), whereas private insurance had a decreased odds of return to OR (p<.05). Within 90 days, male sex, coronary artery disease (CAD), previous spine surgery, procedures with 4 or more levels, and longer length of stay had significantly increased odds of returning to the OR (p<.05). Non-white race, independent ambulatory status pre-operatively, and having private insurance had decreased odds of return to the OR (p<.05). The most common specified reasons for return to the OR within 30 days was hematoma (19%), infection (17%), and wound dehiscence (11%). Within 90 days, reoperation reasons were pain (10%), infection (9%), and hematoma (8%).

CONCLUSION

Reoperation rates after elective cervical spine surgery are 1.24% and 3.30% within 30 and 90 days, respectively. Within 30 days, four or more levels, posterior approach, and longer length of stay were risk factors for reoperation. Within 90 days, male sex, CAD, four or more levels, and longer length of hospital stay were risk factors for reoperation. Non-white demographic and independent preoperative ambulatory status were associated with decreased reoperation rates.

Introduction

Rates of cervical spine surgery in the United States have been significantly increasing, with over 307,000 cervical spine surgeries performed from 2002 to 2011 [1]. Simultaneously, data on complications and outcomes following cervical spine surgery has been growing, with increased focus on public reporting of early complications [2,3]. Complications such as unplanned readmission and reoperation have been increasingly scrutinized, with particular focus on identification of modifiable risk factors. As a result, numerous studies focusing on early readmission rates after cervical spine surgery have been performed; reoperation, however, is a key factor impacting clinical outcomes and only limited data exists regarding early return to the operating room (OR) following cervical spine surgery.

Thirty-day readmission rates have been reported to range from 2.5% to 7.9% after cervical spine procedures [4], [5], [6], [7]. Surgical site infections and postoperative pain have been reported as the most common causes for readmission [5,8]. Across all spine surgeries, 39.3% of all readmissions within 30 days were for wound complications [9]. McCormack et al. found an unplanned readmission rate within 30 days of 3.8%, with 57% of unplanned readmissions requiring return to the operating room; further, 76% of all infections or concern for infection and 50% of draining wounds returned to the operating room [2]. Choy et al. reported a return to the OR rate within 30 days of 4.97% after posterior cervical fusions [4]. As surgical site infections in these patients may frequently warrant intervention, there is less data on how many of these unplanned readmissions need reoperation [10]. Further, analysis beyond the 30-day postoperative period can provide a more comprehensive evaluation of factors impacting reoperation such as wound-related issues and hardware failure.

The Michigan Spine Surgery Improvement Collaborative (MSSIC) is a state-wide, multi-center, spine-specific database focusing on lumbar and cervical spine surgeries for degenerative conditions [11]. The MSSIC database may highlight more relevant causes for reoperation after spine surgery than more general databases such as Medicare claims and American College of Surgeons National Surgical Quality Improvement Program (ACS NSQIP). Prior studies using MSSIC have been performed regarding early readmissions rates for lumbar and cervical fusions without investigating rates or reasons for reoperation [12]. Although a few studies have investigated reoperation rates and reasons within 30 and 90 days following cervical spine surgery [13], [14], [15], these studies have been limited by focusing exclusively on anterior cervical spine surgery, limited follow-up, or using data from a non-spine specific database. The aim of this study is to investigate the rates and reasons for reoperation within 30 and 90 days following elective anterior and posterior cervical spine procedures using a large spine-specific database. These data can help elucidate specific patient and surgeon factors placing patients at higher risk for early reoperation, identify potential modifiable risk factors, and aid providers in pre-operative counselling.