C-reactive protein versus erythrocyte sedimentation rate, white blood cell count and alkaline phosphatase in diagnosing bacteraemia in bone and joint infections.

Aim: Bacteraemia is common in childhood acute bone and joint infections and demands urgent treatment. Blood C-reactive protein (CRP), erythrocyte sedimentation rate and white blood cell count (WBC) are well known and established markers in these infections. Instead, no information is available on serum alkaline phosphatase whose concentration is known to increase in septic conditions.

Methods: In our large prospective treatment trial comprising of 265 children with acute culture-positive bone or joint infection, all these laboratory indices were monitored on admission to hospital. The predictive value to detect bacteraemia was assessed for each of these four indices.

Results: In all, 59% of the patients showed bacteraemia. CRP was significantly (P < 0.05) higher among bacteraemic patients, whereas erythrocyte sedimentation rate, white blood cell count and alkaline phosphatase were not. The area under receiver operator characteristic curve for CRP was 0.588 (CI95% 0.524-0.649) and the significance level P (Area = 0.5) was <0.05.

Conclusion: None of the markers could reliably diagnose bacteraemia. CRP alone was significantly higher among bacteraemic patients.