gms | German Medical Science

Objective: In order to elucidate whether serum inflammatory markers identify patients with local surgical site infection (SSI) as underlying disease for recurrent or new symptomatology following spine surgery, we evaluated the diagnostic potential of interleukin-6 (IL-6) as a marker of SSI in patients undergoing spinal re-operation. The diagnostic impact of IL-6 was compared to the standard serum inflammatory markers C-reactive Protein (CRP) and white blood cell count (WBCC).

Methods: 98 consecutive patients with re-operation after spinal surgery of degenerative spinal canal stenosis entered the study. Baseline patients’ characteristics as well as the above mentioned inflammatory markers were collected and arithmetical means with standard deviation, area under the curve (AUC), thresholds, sensitivity, specificity, positive (+) likelihood ratio (LR) and negative (-) LR with corresponding 95% confidence interval (95%CI) were calculated and correlated with presence or absence of SSI. The AUC describes the diagnostic potential of an inflammatory marker.

Results: 9 Patients suffered from a SSI, whereas the remaining patients had a re-stenosis without any suspicion of SSI. The most significant parameter for diagnosing a SSI was serum IL-6 (cut-off-value > 15.3 pg/ml, AUC = 0.954, SE = 85.7% (95%CI 0.487 – 0.974), SP = 97.3% (95 CI 0.861 – 0.995), +LR = 31.7 (95%CI 4.48 – 224.43), -LR = 0.15 (95%CI 0.02 – 0.90), followed by CRP (AUC = 0.916), and WBCC (AUC = 0.745).

Conclusion: In case of recurrent symptomatology pre-operative raised serum IL-6 levels are significantly associated with SSI. Hence, serum concentrations of IL-6 should be obtained in patients with recurrent symptoms; increased IL-6 levels higher than 15.3 pg/ml should direct the surgeon’s attention to SSI.

Table 1 [Tab. 1]