Lymphopenia and Elevated Blood C-Reactive Protein Levels at Four Days Postoperatively Are Useful Markers for Early Detection of Surgical Site Infection Following Posterior Lumbar Instrumentation Surgery.
METHODS
Case-control study.


OBJECTIVE
To identify the characteristics of candidate indexes for early detection of surgical site infection (SSI).


BACKGROUND
SSI is a serious complication of spinal instrumentation surgery. Early diagnosis and treatment are crucial for the welfare of the patient postoperation.


METHODS
We retrospectively reviewed laboratory data of patients who underwent posterior lumbar instrumentation surgery for degenerative spine disease. The sensitivity and specificity of six laboratory markers for early detection of SSI were calculated: greater elevation of the white blood cell count at day 7 than at day 4 postoperatively, greater elevation of the C-reactive protein (CRP) level at day 7 than at day 4 postoperatively, a CRP level of >10 mg/dL at 4 days postoperatively, neutrophil percentage of >75% at 4 days postoperatively, a lymphocyte percentage of <10% at 4 days postoperatively, and a lymphocyte count of <1,000/µL at 4 days postoperatively. Statistical analysis was via Fisher's exact test and a p-value of <0.05 was considered significant.


RESULTS
In total, 85 patients were enrolled. Of these, five patients developed deep SSI. The sensitivity and specificity of each index were as follows: index 1, 20.0% and 77.5%; index 2, 20.0% and 83.8%; index 3, 40.0% and 97.5%; index 4, 40.0% and 86.3%; index 5, 0% and 96.3%; and index 6, 80.0% and 80.0%. A significant difference was noted for indexes 3 and 6.


CONCLUSIONS
A CRP level of >10 mg/dL at 4 days postoperatively would be useful for definitive diagnosis of SSI, and a lymphocyte count of <1,000/µL at 4 days postoperatively would be a useful screening test for SSI. Although laboratory markers for early detection of SSI have been frequently reported, we believe that it is important to understand the characteristics of each index for a precise diagnosis.
Department of Orthopedic Surgery, Nara Medical University, Nara, Japan.
Eiichiro
E
Iwata
Department of Orthopedic Surgery, Nara Medical University, Nara, Japan.
Hideki
H
Shigematsu
Department of Orthopedic Surgery, Nara Prefecture General Medical Center, Nara, Japan.
Munehisa
M
Koizumi
Department of Orthopedic Surgery, Otemae Hospital, Osaka, Japan.
Hiroshi
H
Nakajima
Department of Orthopedic Surgery, Nara Medical University, Nara, Japan.
Akinori
A
Okuda
Department of Orthopedic Surgery, Nara Medical University, Nara, Japan.
Yasuhiko
Y
Morimoto
Department of Orthopedic Surgery, Nara Medical University, Nara, Japan.
Keisuke
K
Masuda
Department of Orthopedic Surgery, Nara Medical University, Nara, Japan.
Yasuhito
Y
Tanaka
C-reactive protein; Instrumentation; Laboratory marker; Lymphocyte; Surgical site infection