Serum inflammatory markers inaccurate in diagnosing late fracture-related infections

Reference

van den Kieboom J, Bosch P, Plate JDJ, et al. Diagnostic accuracy of serum inflammatory markers in late fracture-related infection. Bone Joint J 2018;100-B(12):1542-1550.

Synopsis

These authors searched PubMed, EMBASE, and the Cochrane Library to find studies published in English, German, or Dutch that evaluated the diagnostic accuracy of specific inflammatory markers in patients with late infections related to a fracture: erythrocyte sedimentation rate (ESR), white blood cell count (WBC), and C-reactive protein (CRP) levels. Late infections were classified if they occurred more than 6 weeks after a traumatic fracture. Two authors independently evaluated potential studies for inclusion and a third author resolved discrepancies. They used a similar approach to assess the methodologic quality of included studies. They excluded studies that did not use a reference standard of intra-operative cultures or 5 months of clinical follow-up. Ultimately, the authors included 6 studies with 582 patients, 161 of whom (28%) had late fracture-related infections. Overall, the studies were of modest quality. The overall diagnostic accuracy for each test was modest at best. For CRP, the overall sensitivity and specificity were 77% and 68%, respectively (positive likelihood ratio [LR+] 2.4; negative likelihood ratio [LR-] 0.3). WBC was 52% sensitive and 67% specific (LR+ 1.6; LR- 0.7) and ESR was only 45% sensitive but 79% specific (LR+ 2.2; LR- 0.7). A positive likelihood ratio more than 10 and a negative likelihood ratio less than 0.1 are the most useful, and values for either that are close to 1 provide no useful diagnostic information. Finally, 4 studies analyzed the utility of combining inflammatory markers, but because of significant variability in the combinations, the authors were not able to pool the data.