Diagnostic Accuracy of Bone Culture Versus Biopsy in Diabetic Foot Osteomyelitis.

Objective: To compare the diagnostic accuracy of bone culture (microbiology) and biopsy (histology) in patients with acute or chronic diabetic foot osteomyelitis (DFO).
Methods: This cross-sectional study involved patients for whom providers had a clinical suspicion of DFO. Two bone samples were taken: one for microbiologic testing and another for histologic testing. The sensitivity, specificity, positive predictive value, negative predictive value, and likelihood ratio were calculated for bone culture results in relation to the probability of DFO diagnosis.
Results: Fifty-two patients were included; 69% had positive bone culture results, and 90.4% had positive histology results (P = .013), and of those 90.4%, 25.5% had acute and 74.5% had chronic DFO. The sensitivity of the microbiologic bone culture result was 0.70, the specificity was 0.40, the positive predictive value was 0.92, and the negative predictive value was 0.13.
Conclusions: Histology provides more accurate diagnosis of DFO than microbiology, especially for patients with chronic DFO. These patients could be underdiagnosed because of false-negative results provided by bone culture. Providers should perform both tests to confirm the presence of DFO.
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