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Invasiveness Index as a Predictor of Surgical Site Infection after Spinal Fusion, Revision Fusion, or Laminectomy

  • Brian L. Hollenbeck (a1), Kevin J. McGuire (a2), Andrew P. White (a2), David S. Yassa (a3) and Sharon B. Wright (a3)...
  • Please note a correction has been issued for this article.



To evaluate invasiveness index as a potential predictor of spine surgical site infection (SSI) after spinal fusion, revision fusion, or laminectomy.


Retrospective cohort study.


Single, large, academic medical center.


Adults undergoing spinal fusion, revision fusion, or laminectomy.


Data were obtained from electronic hospital databases; cases of SSI were extracted from the infection control database using National Healthcare Safety Network (NHSN) definitions. For each case, an invasiveness index, determined by surgical approach, procedure, and number of spine levels treated, was calculated using current procedural terminology (CPT) billing codes. Statistical analyses were performed using univariate and multivariate logistic regression models.


In total, 3,143 patients met inclusion criteria, and 43 of these developed SSI. Multivariate regression showed that advanced age (odds ratio [OR], 1.03; 95% confidence interval [CI], 1.005–1.05, for each year of life) and invasiveness index (medium invasiveness index OR, 5.36; 95% CI, 1.92–14.96; high invasiveness index OR, 14.1; 95% CI, 4.38–45.43) were significant predictors of infection. In subgroup analyses of spinal fusion patients, morbid obesity (OR, 2.542; 95% CI, 1.08–5.99), trauma (OR, 2.41; 95% CI, 1.05–5.55), and invasiveness index (medium invasiveness index OR, 5.39; 95% CI, 1.56–18.61; high invasiveness index OR, 13.44; 95% CI, 3.28–55.01) were significant predictors of SSI. Models containing invasiveness index were compared to NHSN models and demonstrated similar performance.


Invasiveness index is a predictor of SSI after spinal fusion and performs similarly to NHSN models. Invasiveness index shows promise as a potential risk stratification tool that is easily calculated and is available preoperatively.

Infect Control Hosp Epidemiol 2016:1–7


Corresponding author

Address correspondence to Brian L. Hollenbeck, MD, New England Baptist Hospital, Division of Infectious Diseases, 125 Parker Hill Ave, Converse #600, Boston, MA 02120 (


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PREVIOUS PRESENTATION. These data were presented as an Abstract at IDWeek 2014 in Philadelphia, Pennsylvania, on October 10, 2014. EP 1009.



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1. Jenks, PJ, Laurent, M, McQuarry, S, Watkins, R. Clinical and economic burden of surgical site infection (SSI) and predicted financial consequences of elimination of SSI from an English hospital. J Hosp Infect 2014;86:2433.
2. Mu, Y, Edwards, JR, Horan, TC, Berrios-Torres, SI, Fridkin, SK. Improving risk-adjusted measures of surgical site infection for the national healthcare safety network. Infect Control Hosp Epidemiol 2011;32:970986.
3. Nota, SP, Braun, Y, Ring, D, Schwab, JH. Incidence of surgical site infection after spine surgery: What is the impact of the definition of infection? Clin Orthop Rel Res 2015;473:16121619.
4. Cizik, AM, Lee, MJ, Martin, BI, et al. Using the spine surgical invasiveness index to identify risk of surgical site infection: a multivariate analysis. J Bone Joint Surg Am 2012;94:335342.
5. Watanabe, M, Sakai, D, Matsuyama, D, Yamamoto, Y, Sato, M, Mochida, J. Risk factors for surgical site infection following spine surgery: efficacy of intraoperative saline irrigation. J Neurosurg Spine 2010;12:540546.
6. Pull ter Gunne, AF, Cohen, DB. Incidence, prevalence, and analysis of risk factors for surgical site infection following adult spinal surgery. Spine 2009;34:14221428.
7. Tenney, JH, Vlahov, D, Salcman, M, Ducker, TB. Wide variation in risk of wound infection following clean neurosurgery. Implications for perioperative antibiotic prophylaxis. J Neurosurg 1985;62:243247.
8. Klein, JD, Hey, LA, Yu, CS, et al. Perioperative nutrition and postoperative complications in patients undergoing spinal surgery. Spine 1996;21:26762682.
9. Olsen, MA, Mayfield, J, Lauryssen, C, et al. Risk factors for surgical site infection in spinal surgery. J Neurosurg 2003;98:149155.
10. Friedman, ND, Sexton, DJ, Connelly, SM, Kaye, KS. Risk factors for surgical site infection complicating laminectomy. Infect Control Hosp Epidemiol 2007;28:10601065.
11. Levi, AD, Dickman, CA, Sonntag, VK. Management of postoperative infections after spinal instrumentation. J Neurosurg 1997;86:975980.
12. Boston, KM, Baraniuk, S, O’Heron, S, Murray, KO. Risk factors for spinal surgical site infection, Houston, Texas. Infect Control Hosp Epidemiol 2009;30:884889.
13. Radcliff, KE, Rasouli, MR, Neusner, A, et al. Preoperative delay of more than 1 hour increases the risk of surgical site infection. Spine 2013;38:13181323.
14. Thakkar, V, Ghobrial, GM, Maulucci, CM, et al. Nasal MRSA colonization: impact on surgical site infection following spine surgery. Clin Neurol Neurosurg 2014;125:9497.
15. Xing, D, Ma, JX, Ma, XL, et al. A methodological, systematic review of evidence-based independent risk factors for surgical site infections after spinal surgery. Eur Spine J 2013;22:605615.
16. McGregor, JC, Harris, AD. The need for advancements in the field of risk adjustment for healthcare-associated infections. Infect Control Hosp Epidemiol 2014;35:89.
17. Surveillance for Surgical Site Infection (SSI) Events. Center for Disease Control and Prevention website. Published 2015. Accessed on August 25, 2014.
18. Mirza, SK, Martin, BI, Goodkin, R, Hart, RA, Anderson, PA. Developing a toolkit for comparing safety in spine surgery. Instruct Course Lect 2014;63:271286.
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