title: Lymphopenia at 4 Days Postoperatively Is the Most Significant Laboratory Marker for Early Detection of Surgical Site Infection Following Posterior Lumbar Instrumentation Surgery.
abstract: METHODS
  Case control study.
  
  
  OBJECTIVE
  To identify the most significant laboratory marker for early detection of surgical site infection (SSI) using multiple logistic regression analysis.
  
  
  BACKGROUND
  SSI is a serious complication of spinal instrumentation surgery. Early diagnosis and treatment are crucial.
  
  
  METHODS
  We retrospectively reviewed the laboratory data of patients who underwent posterior lumbar instrumentation surgery for degenerative spinal disease from January 2003 to December 2014. Six laboratory markers for early SSI detection were considered: renewed elevation of the white blood cell count, higher at 7 than 4 days postoperatively; renewed elevation of the C-reactive protein (CRP) level, higher at 7 than 4 days postoperatively; CRP level of >10 mg/dL at 4 days postoperatively; neutrophil percentage of >75% at 4 days postoperatively; lymphocyte percentage of <10% at 4 days postoperatively; and lymphocyte count of <1,000/µL at 4 days postoperatively.
  
  
  RESULTS
  Ninety patients were enrolled; five developed deep SSI. Multivariate regression analysis showed that a lymphocyte count of <1,000/µL at 4 days postoperatively was the sole significant independent laboratory marker for early detection of SSI (p=0.037; odds ratio, 11.9; 95% confidence interval, 1.2-122.7).
  
  
  CONCLUSIONS
  A lymphocyte count of <1,000/µL at 4 days postoperatively is the most significant laboratory marker for early detection of SSI.
authors.affiliation: Department of Orthopedic Surgery, Nara Medical University, Nara, Japan.
authors.forename: Eiichiro
authors.initials: E
authors.lastname: Iwata
authors.affiliation: Department of Orthopedic Surgery, Nara Medical University, Nara, Japan.
authors.forename: Hideki
authors.initials: H
authors.lastname: Shigematsu
authors.affiliation: Department of Orthopedic Surgery, Nara Medical University, Nara, Japan.
authors.forename: Akinori
authors.initials: A
authors.lastname: Okuda
authors.affiliation: Department of Orthopedic Surgery, Nara Medical University, Nara, Japan.
authors.forename: Yasuhiko
authors.initials: Y
authors.lastname: Morimoto
authors.affiliation: Department of Orthopedic Surgery, Nara Medical University, Nara, Japan.
authors.forename: Keisuke
authors.initials: K
authors.lastname: Masuda
authors.affiliation: Department of Orthopedic Surgery, Otemae Hospital, Osaka, Japan.
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Nakajima
authors.affiliation: Department of Spine Surgery, Nara Prefecture General Medical Center, Nara, Japan.
authors.forename: Munehisa
authors.initials: M
authors.lastname: Koizumi
authors.affiliation: Department of Orthopedic Surgery, Nara Medical University, Nara, Japan.
authors.forename: Yasuhito
authors.initials: Y
authors.lastname: Tanaka
keywords: Biomarkers; Instrumentation; Leukocytes; Lymphopenia; Surgical wound infection