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Meta-analysis finds CRP has moderate accuracy for diagnosing diabetic foot osteomyelitisC-reactive protein test shows moderate accuracy for diabetic foot bone infection

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Key Takeaway
Consider CRP as a moderate screening adjunct for diabetic foot osteomyelitis, not a definitive test.

This meta-analysis of 12 observational diagnostic studies (1828 total patients) with a retrospective cohort component (265 patients with diabetic foot, including 204 with osteomyelitis) assessed the diagnostic accuracy of C-reactive protein (CRP) for diabetic foot osteomyelitis (DFO). The comparator was the presence versus absence of DFO diagnosis.

In the retrospective cohort, CRP showed an area under the curve (AUC) of 0.63 (95% CI: 0.55, 0.71). The optimal cut-off value was 9.57 mg/l, yielding a sensitivity of 74% and specificity of 53%. The meta-analysis pooled results indicated a sensitivity of 74% (95% CI: 63-83%), specificity of 73% (95% CI: 65-79%), and an AUC of 0.79 (95% CI: 0.75, 0.82). A composite model using a 15.20 mg/l cut-off achieved 80% sensitivity but only 53% specificity.

Safety and tolerability data were not reported. Key limitations were not reported, but the evidence is based on observational diagnostic studies with a retrospective component. The practice relevance is restrained: CRP demonstrates moderate diagnostic utility for DFO and could function as a screening adjunct in clinical evaluation, but its standalone accuracy is insufficient for definitive diagnosis.

A research team wanted to know if a common blood test for inflammation, called C-reactive protein (CRP), could help doctors identify a serious bone infection called osteomyelitis in people with diabetic foot wounds. They looked back at medical records from 265 patients and combined their findings with data from 12 previous studies involving over 1,800 patients total. This type of study is called a meta-analysis.

In the combined analysis of all the studies, the CRP test correctly identified about 74% of people who had the bone infection and correctly ruled it out in about 73% of people who did not have it. This is considered moderate accuracy. However, in the researchers' own smaller group of 265 patients, the test's accuracy was lower. A specific test result level was suggested, but using it would miss some infections and could also incorrectly flag many people who don't have one.

No safety issues with the blood test itself were reported, as it is a standard lab test. The main reason for caution is that this research only looked at past data. The test's performance was not consistent across all studies, and it was not tested prospectively to see how well it works in real-time clinical decisions. For now, this analysis suggests CRP could be one helpful piece of information among others, but it is not a definitive standalone test for this complex infection.

What this means for you:
A CRP blood test may help screen for bone infection in diabetic foot wounds, but it is not a perfect test on its own.

Study Details

Study typeMeta analysis
Sample sizen = 265
EvidenceLevel 1
PublishedApr 2026
View Original Abstract ↓
OBJECTIVE: To determine the composite cut-off value and diagnostic accuracy of C-reactive protein (CRP) for diabetic foot osteomyelitis (DFO). METHOD: A retrospective study of patients was combined with a meta-analysis. Study quality was assessed using the Quality Assessment of Diagnostic Accuracy Studies-2 tool. Pooled sensitivity, specificity and area under the curve (AUC) were calculated via forest plots and summary receiver operating characteristic curves. A composite cut-off model was developed using R 4.4.3 (R Foundation for Statistical Computing, Austria). RESULTS: The experimental cohort comprised 265 patients (204 with DFO and 61 without). The meta-analysis comprised 12 studies, including a total of 1828 patients. The retrospective cohort demonstrated that CRP achieved an AUC of 0.63 (95% confidence interval (CI): 0.55, 0.71) for diagnosing DFO, with an optimal cut-off value of 9.57mg/l (sensitivity 74%, specificity 53%). Meta-analysis revealed pooled sensitivity of 74% (63-83%) and specificity of 73% (65-79%) (AUC=0.79; 95%CI: 0.75, 0.82). The composite model suggested a CRP cut-off of 15.20mg/l (sensitivity 80%, specificity 53%). CONCLUSION: In this study, CRP demonstrated moderate diagnostic utility for DFO and could function as a screening adjunct.
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