C-reactive protein and interleukin-6 levels in the early detection of infection after open fractures

Purpose. To measure C-reactive protein (CRP) and interleukin-6 (IL-6) levels in 30 patients with open fractures and correlate the levels with infection. Methods. 29 men and one woman aged 9 to 70 (mean, 37) years presented with open fractures of the upper or lower extremity within 12 hours of injury and underwent debridement and external fixation 3 to 40 (mean, 16) hours after injury. Serum CRP and IL-6 concentrations were measured preoperatively and on postoperative days 2 and 4. CRP was measured using latex agglutination and nephelometry, and IL-6 by enzyme-linked immunosorbent assay. The mean CRP and IL-6 levels in infected and non-infected patients were compared. The trend of CRP and IL-6 levels within the infected group was analysed. Correlations between CRP and infection, and between IL-6 and infection were analysed. Results. 11 of the 30 patients developed wound infection. The day-2 CRP levels of 30 patients were positive (range, 7-28 mu g/ml). In 27 patients, the CRP levels were higher on day 2 than preoperation. On day 4, CRP levels declined sharply in patients without infection (mean, 8 mu g/ml) but were persistently elevated in patients with infection (mean, 17 mu g/ml). The sensitivity and specificity of the CRP test were 100% and 42%, respectively. In the 11 patients with infection, the IL-6 concentrations were elevated at day 2 (mean, 689 pg/ml) and decreased progressively at day 4 (mean, 175 pg/ml). The sensitivity and specificity of the IL-6 test were 90% and 100%, respectively. Infection correlated with CRP and IL-6 levels. Conclusions. Serial serum measurements of IL-6 and CRP levels help in the early diagnosis of infections after open fractures before they are clinically evident.