title: Risk of infection following posterior instrumented lumbar fusion for degenerative spine disease in 817 consecutive cases.
abstract: OBJECTIVE
  Posterior lumbar spinal fusion for degenerative spine disease is a common procedure, and its use is increasing annually. The rate of infection, as well as the factors associated with an increased risk of infection, remains unclear for this patient population. A better understanding of these features may help guide treatment strategies aimed at minimizing infection for this relatively common procedure. The authors' goals were therefore to ascertain the incidence of postoperative spinal infections and identify factors associated with postoperative spinal infections.
  
  
  METHODS
  Data obtained in adult patients who underwent instrumented posterior lumbar fusion for degenerative spine disease between 1993 and 2010 were retrospectively reviewed. Stepwise multivariate proportional hazards regression analysis was used to identify factors associated with infection. Variables with p < 0.05 were considered statistically significant.
  
  
  RESULTS
  During the study period, 817 consecutive patients underwent lumbar fusion for degenerative spine disease, and 37 patients (4.5%) developed postoperative spine infection at a median of 0.6 months (IQR 0.3-0.9). The factors independently associated with an increased risk of infection were increasing age (RR 1.004 [95% CI 1.001-1.009], p = 0.049), diabetes (RR 5.583 [95% CI 1.322-19.737], p = 0.02), obesity (RR 6.216 [95% CI 1.832-9.338], p = 0.005), previous spine surgery (RR 2.994 [95% CI 1.263-9.346], p = 0.009), and increasing duration of hospital stay (RR 1.155 [95% CI 1.076-1.230], p = 0.003). Of the 37 patients in whom infection developed, 21 (57%) required operative intervention but only 3 (8%) required instrumentation removal as part of their infection management.
  
  
  CONCLUSIONS
  This study identifies that several factors--older age, diabetes, obesity, prior spine surgery, and length of hospital stay--were each independently associated with an increased risk of developing infection among patients undergoing instrumented lumbar fusion for degenerative spine disease. The overwhelming majority of these patients were treated effectively without hardware removal.
authors.affiliation: Department of Neurosurgery, Johns Hopkins University School of Medicine, Baltimore, Maryland.
authors.forename: Kaisorn L
authors.initials: KL
authors.lastname: Chaichana
authors.forename: Mohamad
authors.initials: M
authors.lastname: Bydon
authors.forename: David R
authors.initials: DR
authors.lastname: Santiago-Dieppa
authors.forename: Lee
authors.initials: L
authors.lastname: Hwang
authors.forename: Gregory
authors.initials: G
authors.lastname: McLoughlin
authors.forename: Daniel M
authors.initials: DM
authors.lastname: Sciubba
authors.forename: Jean-Paul
authors.initials: JP
authors.lastname: Wolinsky
authors.forename: Ali
authors.initials: A
authors.lastname: Bydon
authors.forename: Ziya L
authors.initials: ZL
authors.lastname: Gokaslan
authors.forename: Timothy
authors.initials: T
authors.lastname: Witham
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D006801:Humans; D015994:Incidence; D008159:Lumbar Vertebrae / Q000601:surgery*; D008297:Male; D008875:Middle Aged; D012189:Retrospective Studies; D013122:Spinal Diseases / Q000601:surgery*; D013123:Spinal Fusion / Q000009:adverse effects* / Q000295:instrumentation; D013530:Surgical Wound Infection / Q000453:epidemiology / Q000209:etiology*; D016896:Treatment Outcome