Adverse events and their risk factors 90 days after cervical spine surgery: analysis from the Michigan Spine Surgery Improvement Collaborative

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The Michigan Spine Surgery Improvement Collaborative (MSSIC) is a statewide, multicenter quality improvement initiative. Using MSSIC data, the authors sought to identify 90-day adverse events and their associated risk factors (RFs) after cervical spine surgery.


A total of 8236 cervical spine surgery cases were analyzed. Multivariable generalized estimating equation regression models were constructed to identify RFs for adverse events; variables tested included age, sex, diabetes mellitus, disc herniation, foraminal stenosis, central stenosis, American Society of Anesthesiologists Physical Classification System (ASA) class > II, myelopathy, private insurance, anterior versus posterior approach, revision procedures, number of surgical levels, length of procedure, blood loss, preoperative ambulation, ambulation day of surgery, length of hospital stay, and discharge disposition.


Ninety days after cervical spine surgery, adverse events identified included radicular findings (11.6%), readmission (7.7%), dysphagia requiring dietary modification (feeding tube or nothing by mouth [NPO]) (6.4%), urinary retention (4.7%), urinary tract infection (2.2%), surgical site hematoma (1.1%), surgical site infection (0.9%), deep vein thrombosis (0.7%), pulmonary embolism (0.5%), neurogenic bowel/bladder (0.4%), myelopathy (0.4%), myocardial infarction (0.4%), wound dehiscence (0.2%), claudication (0.2%), and ileus (0.2%). RFs for dysphagia included anterior approach (p < 0.001), fusion procedures (p = 0.030), multiple-level surgery when considering anterior procedures only (p = 0.037), and surgery duration (p = 0.002). RFs for readmission included ASA class > II (p < 0.001), while preoperative ambulation (p = 0.001) and private insurance (p < 0.001) were protective. RFs for urinary retention included increasing age (p < 0.001) and male sex (p < 0.001), while anterior-approach surgery (p < 0.001), preoperative ambulation (p = 0.001), and ambulation day of surgery (p = 0.001) were protective. Preoperative ambulation (p = 0.010) and anterior approach (p = 0.002) were protective of radicular findings.


A multivariate analysis from a large, multicenter, prospective database identified the common adverse events after cervical spine surgery, along with their associated RFs. This information can lead to more informed surgeons and patients. The authors found that early mobilization after cervical spine surgery has the potential to significantly decrease adverse events.

ABBREVIATIONS ASA = American Society of Anesthesiologists Physical Classification System; BCBSM = Blue Cross Blue Shield of Michigan; BCN = Blue Care Network; CMS = Centers for Medicare & Medicaid Services; DRG = diagnosis-related group; DVT = deep vein thrombosis; GEE = generalized estimating equation; MSSIC = Michigan Spine Surgery Improvement Collaborative; NPO = nothing by mouth; PE = pulmonary embolism; POD = postoperative day; RF = risk factor; UTI = urinary tract infection.

Article Information

Correspondence Victor Chang: Henry Ford West Bloomfield Hospital, West Bloomfield Township, MI.

INCLUDE WHEN CITING Published online February 15, 2019; DOI: 10.3171/2018.10.SPINE18666.

Disclosures Dr. Schwalb: salary support for MSSIC role as Associate Director from Blue Cross Blue Shield of Michigan, consultant for Huidant, LLC, and clinical or research support for the study described from Medtronic. Dr. Park: consultant for Globus, NuVasive, Medtronic, and Allosource; and royalties from Globus. Dr. Chang: consultant for Globus Medical, K2M, and SpineGuard.

Although Blue Cross Blue Shield of Michigan and MSSIC work collaboratively, the opinions, beliefs, and viewpoints expressed by the authors do not necessarily reflect the opinions, beliefs, and viewpoints of BCBSM or any of its employees. Support for MSSIC is provided by Blue Cross and Blue Shield of Michigan and Blue Care Network as part of the BCBSM Value Partnerships program.

© AANS, except where prohibited by US copyright law.



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    A: Comprehensive map of all participants within the MSSIC. Each wave represents a different time of entry since MSSIC’s inception in 2014. B: Heat map showing the populations of MSSIC patients based on home ZIP code. The darker the color, the greater the number of patients from that particular ZIP code. Most of MSSIC’s surgical population is drawn from the state of Michigan and is concentrated around large urban areas. Source:





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