Decreased accuracy of erythrocyte sedimentation rate in diagnosing osteomyelitis in diabetic foot infection patients with severe renal impairment: A retrospective cross-sectional study.

BACKGROUND: Rapid diagnosis and treatment of diabetic foot osteomyelitis (DFO) could reduce the risk of amputation and death in patients with diabetic foot infection (DFI). Erythrocyte sedimentation rate (ESR) is considered the most useful serum inflammatory marker for the diagnosis of DFO. However, whether severe renal impairment (SRI) affects its diagnostic accuracy has not been reported previously. OBJECTIVE: To investigate the accuracy of ESR in diagnosing DFO in DFI patients with and without SRI. METHODS: This was a retrospective cross-sectional study. From the inpatient electronic medical record system, the investigators extracted demographic information, diagnostic information, and laboratory test results of patients with DFI who had been hospitalized in Longhua Hospital from January 1, 2016 to September 30, 2021. Logistic regression was performed to analyze the interaction between ESR and SRI with adjustment for potential confounders. The area under the curve (AUC), cutoff point, sensitivity, specificity, prevalence, positive predictive value (PPV), negative predictive value (NPV), positive likelihood ratio (LR+), and negative likelihood ratio (LR-) were analyzed by receiver operating characteristic (ROC) curve analysis and VassarStats. RESULTS: A total of 364 DFI patients were included in the analysis. The logistic regression analysis results showed that elevated ESR increased the probability of diagnosing DFO (adjusted odds ratio [OR], 2.40; 95% confidence interval [CI], 1.75-3.28; adjusted P < 0.001); SRI was not associated with the diagnosis of DFO (adjusted OR, 3.20; 95% CI, 0.40-25.32; adjusted P = 0.271), but it had an obstructive effect on the diagnosis of DFO by ESR (adjusted OR, 0.48; 95% CI, 0.23-0.99; adjusted P = 0.048). ROC analysis in DFI patients without SRI revealed that the AUC of ESR to diagnose DFO was 0.76 (95% CI, 0.71-0.81), with the cutoff value of 45 mm/h (sensitivity, 67.8%; specificity, 78.0%; prevalence, 44.7%; PPV, 71.3%; NPV, 75.0%; LR+, 3.08; LR-, 0.41). In contrast, in patients with SRI, the AUC of ESR to diagnose DFO was 0.57 (95% CI, 0.40-0.75), with the cutoff value of 42 mm/h (sensitivity, 95.0%; specificity, 29.2%; prevalence, 45.5%; PPV, 52.8%; NPV, 87.5%; LR+, 1.34; LR-, 0.17). CONCLUSIONS: The accuracy of ESR in diagnosing DFO in DFI patients with SRI is reduced, and it may not have clinical diagnostic value in these patients.

Protein chip for detection of different HCV antibodies: preparation, quality control, and clinical evaluation.

INTRODUCTION: As a contagious disease caused by hepatitis C virus (HCV) hepatitis C is a serious threat to human health. Therefore, the detection and verification of HCV infection is very important in the treatment of hepatitis C. This study investigated the preparation, quality control, and clinical evaluation of a protein chip capable of simultaneously detecting different HCV antibodies. The aim was to establish a convenient method for the detection of HCV. METHOD: To prepare the protein chip, six antigens including five recombinant HCV antigens (chimeric, core, NS3, NS4, and NS5) and interleukin (IL)-1 were arrayed onto aldehyde-coated slides and blocked using 10% calf serum in phosphate buffered saline. After dilution with sample solution, the serum sample was added to a reaction well on the protein chip. After incubation for 30 minutes at 37 degrees C, fluorescence Cy3-labeled rabbit antihuman IgG was added and incubated again for 30 minutes at 37 degrees C, and then scanned. Positive or negative controls were established from serum samples with or without HCV infection. Clinical evaluation was done by detecting 490 serum samples using the protein chips and ELISA reagents, with 150 of the 490 serum samples confirmed by recombinant immunoblot assay (RIBA). RESULTS: The protein chip for detection of five HCV antibodies was successfully prepared. Fifteen positive controls and 15 negative controls were established as standard samples for quality control. The quality control-passed protein chip was tested again using the standard of the National Institute for the Control of Pharmaceutical and Biological Products (NICPBP), and met the quality control criteria prescribed by the NICPBP. In the clinical evaluation with 490 samples, the coincidence rates between the protein-chip assay and ELISA were 97.4% for positive and 100% for negative results. Five inconsistent samples that were positive in ELISA, but non-positive (four samples) or negative (one) in the protein-chip assay, were confirmed by RIBA (gold standard) to be four non-positive and one negative. The results of 150 samples showed the coincidence rates between protein chip and RIBA were 98.15% for positive and 96.88% for single-segment positive. CONCLUSION: The protein-chip assay has higher sensitivity and specificity than ELISA and has a high coincidence rate with RIBA. The protein chip, characterized by its easy operation and low economic cost, will be very useful for in vitro detection of HCV antibodies.