Elsevier

The Spine Journal

Volume 16, Issue 5, May 2016, Pages 632-642
The Spine Journal

Clinical Study
Diagnosis and neurologic status as predictors of surgical site infection in primary cervical spinal surgery

https://doi.org/10.1016/j.spinee.2016.01.019Get rights and content

Abstract

Background Context

Surgical site infection (SSI) incidence after cervical spinal surgery ranges from 0.1% to 17%. Although the general risk factors for SSI have been discussed, the relationship of neurologic status and trauma to SSI has not been explicitly explored.

Purpose

This study aimed to study associated risk factors and to report the incidence of SSI in patients who have undergone cervical spinal surgery with the following four preoperative diagnoses: (1) degenerative disease with no myelopathy (MP), (2) degenerative disease with MP, (3) traumatic cervical injury without spinal cord injury (SCI), (4) traumatic cervical injury with SCI. We hypothesize that SSI incidence would increase from Group (1) to Group (4).

Study Design

Retrospective database analysis was carried out.

Patients Sample

We used International Classification of Diseases codes to identify the four groups of patients in the U.S. Nationwide Inpatient Sample (NIS) from the years 2000 to 2011. We complemented this study with a similar search in our institutional database (ID) from the years 2000 to 2013. Patients with concomitant congenital deformity, infection, inflammatory disease, and neoplasia were excluded, as were revision surgeries.

Outcome Measures

The primary outcome studied was the occurrence of SSI. Statistical analyses included bivariate comparisons and chi-square distribution of demographic data and multivariable regression for demographic, surgical, and outcome variables.

Results

A total of 1,247,281 and 5,540 patients met inclusion criteria in the NIS database and the ID, respectively. Overall SSI incidence was 0.73% (NIS) versus 1.75% (ID). Surgical site infection incidence increased steadily from 0.52% in Group (1) to 1.97% in Group (4) in the NIS data and from 0.88% to 5.54% in the ID. Differences between diagnostic groups and cohorts reached statistical significance. Surgical site infection was predicted significantly by status (odds ratio [OR] 1.69, p<.0001) and trauma (OR 1.30, p=.0003) in the NIS data. Other significant predictors included the following: approach, number of levels fused, female gender, black race, medium size hospital, rural hospital, large hospital, western US hospital and Medicare coverage. In the ID, only trauma (OR 2.11, p=.03) reached significance when accounting for comorbidities.

Conclusions

Both primary diagnosis (trauma vs. degenerative) and neurologic status (MP or SCI) were found to be strong and independent predictors of SSI in cervical spine surgery.

Introduction

The annual volume of cervical spine operations performed in the United States has increased steadily over the past decades [1], [2]. These surgeries are typically performed to treat cervical stenosis causing radiculopathy or myelopathy, and less commonly for trauma, neoplasm, or infection [3]. Not only has the absolute number of patients undergoing spine surgeries increased, but also has the average age and comorbidity index [1], [2]. However, this rise was associated with neither higher morbidity nor mortality, and in fact, average total length of hospital stay has decreased over the same time period [2]. Wound-related complications, including infections, are a relatively common postoperative problem, increasing overall morbidity, mortality, and health-care costs [4], [5]. The overall incidence of infections in spine surgeries varies from 0% to 17% depending on the diagnosis, surgical approach, operative region, number of levels, and use of instrumentation [6], [7], [8], [9], [10]. This incidence varies between studies based on the definition and methods used to monitor for infection. Other common risk factors for surgical site infections (SSIs) include comorbidities such as age over 60 years, diabetes, malnutrition, and obesity, among others [11], [12], [13], [14], [15]. Multiple studies have demonstrated a relatively high risk of infection after posterior cervical surgery ranging from 3% to 94% [15], [16] compared with a much lower rate with anterior-only approaches [7], [17], [18]. Higher complication rates have also been reported after posterior stabilization for traumatic cervical injuries, rheumatoid cervical disease, and in patients with myelopathy, upward of 17% in some cases [6], [7], [16], [19]. Infection after posttraumatic posterior cervical fusion has also been associated with delays to operative intervention, increased postoperative intensive care unit stay, and use of a postoperative semi-rigid cervical orthosis [20].

Although numerous risk factors for infection after cervical spinal surgery have been identified, the relationship between preoperative neurologic status and infection has not been fully explored. Increased approach-related perioperative morbidity was demonstrated in patients with cervical spondylotic myelopathy [3], [7], [10], [21]. Increased morbidity and mortality have also been documented in patients following surgery for traumatic injuries compared with patients undergoing surgery for non-traumatic indications, and a single study linked spinal cord injury (SCI) to infectious outcomes [6], [8], [20], [22], [23]. However, no studies have been done to compare incidence of SSI based on neurologic status in patients undergoing cervical procedures for either degenerative or traumatic indications. Thus, the premise of this study was to report the incidence of SSI in patients who have undergone cervical spinal surgery with the following four preoperative diagnoses: (1) cervical radiculopathy, (2) cervical myeloradiculopathy, (3) traumatic cervical injury without neurologic injury, and (4) traumatic cervical injury with neurologic injury.

The hypothesis is that the infection rate—and thus perioperative morbidity—will increase in a stepwise fashion moving from Group (1) to Group (4).

Section snippets

Data sources

The U.S. Nationwide Inpatient Sample (NIS) database was used to access patient information from the years 2000 to 2011. The NIS is the largest publicly available all-payer inpatient care database containing de-identified discharge data, approximating a 20% stratified sample of U.S. community hospitals [24]. The Agency for Healthcare Research and Quality reports high NIS accuracy and agreement between data estimated by the NIS and the National Hospital Discharge Survey. The NIS data quality is

(a) NIS data

A total of 1,872,327 patients were identified from the NIS database that met inclusion criteria from 2000 until 2011. Analysis detected high rates of inconsistent or missing data between the years 2000 and 2003. These four years were therefore dropped from the final analyses and only years 2004–2011 were considered. A total of 1,247,281 patients remained in the final cohort. Only 68,482 patients had a traumatic diagnosis (5.49%). A total of 345,458 patients had myelopathy at the time of

Discussion

Published SSI incidence for spine surgery ranges from 0.5% to 12% [25]. This wide range of infection rates is related to the variations in average age, indication, approach, type(s) of procedures, and use of instrumentation, among other factors. Another source of variability is the diagnostic criteria and the length of monitoring for the infection itself [26], [27], [28]. Other proposed risk factors include ethnicity [29], insurance status [12], [30], and the hospital setting. As such, many

Conclusions

This is the first report directly linking diagnosis and neurologic status to the occurrence of SSI. We found a higher incidence of infection in patients presenting with spinal trauma as well as patients with neurologic injury irrespective of the etiology. Both primary diagnosis (traumatic injury vs. degenerative) and neurologic status (myelopathy or SCI) were found to be strong and independent predictors of SSIs after cervical spine surgery. These findings underscore the importance of

References (39)

  • S.G. Memtsoudis et al.

    Increased in-hospital complications after primary posterior versus primary anterior cervical fusion

    Clin Orthop Relat Res

    (2011)
  • M. Boakye et al.

    Cervical spondylotic myelopathy: complications and outcomes after spinal fusion

    Neurosurgery

    (2008)
  • FangA. et al.

    Risk factors for infection after spinal surgery

    Spine

    (2005)
  • M.W. Manoso et al.

    Medicaid status is associated with higher surgical site infection rates after spine surgery

    Spine

    (2014)
  • A.J. Schoenfeld et al.

    Risk factors for immediate postoperative complications and mortality following spine surgery: a study of 3475 patients from the National Surgical Quality Improvement Program

    J Bone Joint Surg Am

    (2011)
  • P.A. Kalanithi et al.

    Morbid obesity increases cost and complication rates in spinal arthrodesis

    Spine

    (2012)
  • A. Veeravagu et al.

    Risk factors for postoperative spinal wound infections after spinal decompression and fusion surgeries

    Spine

    (2009)
  • HuangR.C. et al.

    Treatment of multilevel cervical spondylotic myeloradiculopathy with posterior decompression and fusion with lateral mass plate fixation and local bone graft

    J Spinal Disord Tech

    (2003)
  • B.K. Kwon et al.

    A prospective randomized controlled trial of anterior compared with posterior stabilization for unilateral facet injuries of the cervical spine

    J Neurosurg Spine

    (2007)
  • Cited by (18)

    • Nuchal thickness and increased risk of surgical site infection in posterior cervical operations

      2021, Clinical Neurology and Neurosurgery
      Citation Excerpt :

      Diabetes mellitus, obesity (BMI > 35 kg/m2), subcutaneous fat thickness, multiple medical comorbidities, current smoker status, and malnutrition have been specifically shown to be risk factors for SSI in spinal surgery [7,9–17]. Within cervical surgeries, posterior approach is consistently reported to be a risk factor [7,18–22]. There exists mixed evidence for significant associations between SSI and age, duration of surgery, surgical team, intraoperative blood loss, dural tear, or urinary tract infection/urinary catheter use [17].

    • Risk factors associated with reoperation in posterior cervical fusions: A large-scale retrospective analysis

      2020, Clinical Neurology and Neurosurgery
      Citation Excerpt :

      Reoperations for “mechanical” reasons such as screw pullout and adjacent segment disease did not account for even half of the reoperations, which may account for the lack of significance noted in the groups with fusions including C2 or CTJ. Prior studies have shown that PCF alone or when combined with anterior fusions confer a higher risk of infection than anterior fusions alone [29]. The reoperation rate for infection in patients with PCF in this study was found to be 3.0 %.

    • Using artificial intelligence (AI) to predict postoperative surgical site infection: A retrospective cohort of 4046 posterior spinal fusions

      2020, Clinical Neurology and Neurosurgery
      Citation Excerpt :

      Similarly, this study found that ICU admission, increasing Charlson comorbidity score, white race and male to be protective against SSI. While it has been documented that both race and sex contribute to overall infection rates[37], the trend of ICU admissions and increasing Charlson score as protective are unexpected. In fact, the majority of literature currently available suggests the opposite, that increasing Charlson comorbidity scores and ICU admission lead to a higher incidence of infection [35,38].

    View all citing articles on Scopus

    FDA device/drug status: Not applicable.

    Author disclosures: SH: Nothing to disclose. PWM: Stocks: Globus (F), outside the submitted work. MM: Nothing to disclose. CR: Nothing to disclose. CKK: Nothing to disclose. ARV: Service on Scientific Advisory Board/Board of Directors/Service on Committees: Progressive Spinal Technologies (Nonfinancial), Flagship Surgical (Nonfinancial), AO Spine (Nonfinancial), Innovative Surgical Design (Nonfinancial), Association of Collaborative Spine Research (Nonfinancial), Prime Surgeons (Nonfinancial); Consulting/Independent Contractor: DePuy (B), Medtronics (B), Stryker Spine (C), Globus (C), Stout Medical (Nonfinancial), Gerson Lehman Group (Nonfinancial), Guidepoint Global (B), Medacorp (B), Innovative Surgical Design (Nonfinancial), Orthobullets (Nonfinancial), Expert testimony (Nonfinancial), Nuvasive (Nonfinancial); Receipt of Royalty Payments: Medtronics (F), Stryker Spine (G), Globus (F), Aesculap (B), Jaypee (B), Elsevier (B), Taylor Francis (A); Stock/Stock Option Ownership Interests: Replication Medica (<1%), Globus (<1%), Paradigm Spine (<1%), Stout Medical (1%), Progressive Spinal Technologies (<1%), Advanced Spinal Intellectual Properties (30%), Spine Medica (<1%), Computational Biodynamics (<1%), Spinology (<1%), In Vivo (<1%), Flagship Surgical (<1%), Cytonics (<1%), Bonovo Orthopaedics (<1%), Electrocore (<1%), Gamma Spine (<1%), Location Based Intelligence (20%), FlowPharma (<1%), Rothman Institute and Related Properties (3%), Innovative Surgical Design (1%), Avaz Surgical (<1%), Prime Surgeons (<1%), Dimension Orthotics LLC (<1%), outside the submitted work.

    The disclosure key can be found on the Table of Contents and at www.TheSpineJournalOnline.com.

    View full text