Diagnostic Utility of Erythrocyte Sedimentation Rate and C-Reactive Protein in Osteomyelitis of the Foot in Persons Without Diabetes

Update of biomarkers to diagnose diabetic foot osteomyelitis: A meta-analysis and systematic review

The aim of this study was to evaluate the diagnostic characteristics of biomarker for diabetic foot osteomyelitis (DFO). We searched PubMed, Scopus, Embase and Medline for studies who report serological markers and DFO before December 2022. Studies must include at least one of the following diagnostic parameters for biomarkers: area under the curve, sensitivities, specificities, positive predictive value, negative predictive value. Two authors evaluated quality using the Quality Assessment of Diagnostic Accuracy Studies tool. We included 19 papers. In this systematic review, there were 2854 subjects with 2134 (74.8%) of those patients being included in the meta-analysis. The most common biomarkers were erythrocyte sedimentation rate (ESR), C-reactive protein (CRP) and procalcitonin (PCT). A meta-analysis was then performed where data were evaluated with Forrest plots and receiver operating characteristic curves. The pooled sensitivity and specificity were 0.72 and 0.75 for PCT, 0.72 and 0.76 for CRP and 0.70 and 0.77 for ESR. Pooled area under the curves for ESR, CRP and PCT were 0.83, 0.77 and 0.71, respectfully. Average diagnostic odds ratios were 16.1 (range 3.6-55.4), 14.3 (range 2.7-48.7) and 6.7 (range 3.6-10.4) for ESR, CRP and PCT, respectfully. None of the biomarkers we evaluated could be rated as 'outstanding' to diagnose osteomyelitis. Based on the areas under the curve, ESR is an 'excellent' biomarker to detect osteomyelitis, and CRP and PCT are 'acceptable' biomarkers to diagnose osteomyelitis. Diagnostic odds ratios indicate that ESR, CRP and PCT are 'good' or 'very good' tools to identify osteomyelitis.

The infected diabetic foot: Modulation of traditional biomarkers for osteomyelitis diagnosis in the setting of diabetic foot infection and renal impairment

The objective of this paper was to investigate erythrocyte sedimentation rate (ESR) and c-reactive protein (CRP) in diagnosing pedal osteomyelitis (OM) in patients with and without diabetes, and with and without severe renal impairment (SRI). This was a retrospective cohort study of patients with moderate and severe foot infections. We evaluated three groups: Subjects without diabetes (NDM), subjects with diabetes and without severe renal insufficiency (DM-NSRI), and patients with diabetes and SRI (DM-SRI). SRI was defined as eGFR <30. We evaluated area under the curve (AUC), cutoff point, sensitivity and specificity to characterize the accuracy of ESR and CRP to diagnose OM. A total of 408 patients were included in the analysis. ROC analysis in the NDM group revealed the AUC for ESR was 0.62, with a cutoff value of 46 mm/h (sensitivity, 49.0%; specificity, 76.0%). DM-NSRI subjects showed the AUC for ESR was 0.70 with the cutoff value of 61 mm/h (sensitivity, 68.9%; specificity 61.8%). In DM-SRI, the AUC for ESR was 0.67, with a cutoff value of 119 mm/h (sensitivity, 46.4%; specificity, 82.40%). In the NDM group, the AUC for CRP was 0.55, with a cutoff value of 6.4 mg/dL (sensitivity, 31.3%; specificity, 84.0%). For DM-NSRI, the AUC for CRP was 0.70, with a cutoff value of 8 mg/dL (sensitivity, 49.2%; specificity, 80.6%). In DM-SRI, the AUC for CRP was 0.62, with a cutoff value of 7 mg/dL (sensitivity, 57.1%; specificity, 67.7%). While CRP demonstrated relatively consistent utility, ESR's diagnostic cutoff points diverged significantly. These results highlight the necessity of considering patient-specific factors when interpreting ESR results in the context of OM diagnosis.

The infected diabetes-related foot: Comparison of erythrocyte sedementation rate/albumin and C-reactive protein/albumin ratios with erythrocyte sedimentation rate and C-reactive protein to differentiate bone and soft tissue infections

The objective of this study was to evaluate the effectiveness of C-reactive protein (CRP)/albumin, erythrocyte sedimentation rate (ESR)/albumin ratio, ESR, CRP and albumin to differentiate bone and soft tissue infection in persons with diabetes. We retrospectively evaluated 242 individuals admitted to hospital with diabetes-related foot infections (DFI). We categorised DFI cases as either bone (OM) or soft tissue infection based on bone culture and/or histology. We evaluated the diagnostic accuracy of CRP, ESR, albumin, CRP/albumin and ESR/albumin as biomarkers to diagnose OM in persons with diabetes. The median age was 53 years (74% male). There were 224 diabetes-related patients of which 125 had been diagnosed with osteomyelitis. The ESR/albumin and CRP/albumin ratios cut-points were >17.84 and >1.83, respectively. ESR/albumin and CRP/albumin ratios had similar diagnostic parameters: AUC (0.71, 0.71), sensitivity (70.0%, 57.0%), specificity (62.0%, 75.0%), positive predictive value (67.0%, 71.0%) and negative predictive value (66.0% and 71.0%). In contrast diagnostic efficiency of CRP and ESR were AUC 0.71 and 0.71, sensitivity (45.6%, 71.2%), specificity (85.5%, 60.7%), positive predictive value (70.0%, 65.9%) and negative predictive value (59.5%, 66.4%), respectively. When comparing area under the curves, the results showed that ESR/albumin was not significantly different to ESR alone (Delong test pvs ESR  >0.1). Similarly, CRP/albumin was not significantly different to CRP alone (Delong test pvs CRP  >0.1). In conclusion, ESR/albumin and CRP/albumin ratios provided comparable results as using ESR and CRP alone.

C-Reactive Protein: Pathophysiology, Diagnosis, False Test Results and a Novel Diagnostic Algorithm for Clinicians

The current literature provides a body of evidence on C-Reactive Protein (CRP) and its potential role in inflammation. However, most pieces of evidence are sparse and controversial. This critical state-of-the-art monography provides all the crucial data on the potential biochemical properties of the protein, along with further evidence on its potential pathobiology, both for its pentameric and monomeric forms, including information for its ligands as well as the possible function of autoantibodies against the protein. Furthermore, the current evidence on its potential utility as a biomarker of various diseases is presented, of all cardiovascular, respiratory, hepatobiliary, gastrointestinal, pancreatic, renal, gynecological, andrological, dental, oral, otorhinolaryngological, ophthalmological, dermatological, musculoskeletal, neurological, mental, splenic, thyroid conditions, as well as infections, autoimmune-supposed conditions and neoplasms, including other possible factors that have been linked with elevated concentrations of that protein. Moreover, data on molecular diagnostics on CRP are discussed, and possible etiologies of false test results are highlighted. Additionally, this review evaluates all current pieces of evidence on CRP and systemic inflammation, and highlights future goals. Finally, a novel diagnostic algorithm to carefully assess the CRP level for a precise diagnosis of a medical condition is illustrated.

Efficacy and Safety of Antibiotic Impregnated Microporous Nanohydroxyapatite Beads for Chronic Osteomyelitis Treatment: A Multicenter, Open-Label, Prospective Cohort Study

Chronic osteomyelitis is still a serious health problem that causes disabling conditions and has an impact on the quality of life. The objective of this study was to determine the clinical efficacy and safety of localized antibiotics delivery via impregnated microporous nanohydroxyapatite (nHA-ATB) beads for chronic osteomyelitis treatment. A total of 62 patients were enrolled in this study. After radical surgical debridement, the bone defect was filled with three types of antibiotics (vancomycin or gentamicin or fosfomycin) impregnated HA beads. The follow-up period was 48 weeks. It was found that the success rate was approximately 98% with a re-infection in only one patient. Quality of life of all patients after treatment improved significantly over time. Systemic exposure to vancomycin and gentamicin after beads implantation was limited and high local antibiotics concentrations were found in wound drainage fluid at 24, 48 and 72 h. Blood biochemistry measurements did not show any nephrotoxic or hepatotoxic effects. 20 adverse events were reported, but 90% of the events were resolved without having to remove the beads and the patients recovered. Satisfactory outcomes were observed in terms of success rate, quality of life and adverse effect. nHA-ATB beads impregnated by vancomycin or gentamicin or fosfomycin could potentially be employed as an alternative product of choice for localized antibiotics delivery in chronic osteomyelitis treatment.

Inflammatory response in confirmed non-diabetic foot and ankle infections: A case series with normal inflammatory markers

BACKGROUND

The distinction between foot and ankle wound healing complications as opposed to infection is crucial for the appropriate and efficacious allocation of antibiotic therapy. Multiple reports have focused on the diagnostic accuracy of different inflammatory markers, however, mainly in the diabetic population.

AIM

To evaluate the diagnostic accuracy of white cell count (WCC) and C-reactive protein (CRP) as diagnostic tools for this distinction in the non-diabetic cohort.

METHODS

Data was reviewed from a prospectively maintained Infectious Diseases Unit database of 216 patients admitted at Leicester University Hospitals–United Kingdom with musculoskeletal infections over the period between July 2014 and February 2020 (68 mo). All patients with confirmed diagnosis of diabetes were excluded while only those with confirmed microbiological or clinical diagnosis of foot or ankle infection were included in our study. For the included patients, we retrospectively retrieved the inflammatory markers (WCCs and CRP) at the time of presentation. Values of CRP 0-10 mg/L and WCC 4.0-11.0 × 10⁹/L were considered normal.

RESULTS

After exclusion of patients with confirmed diabetes, 25 patients with confirmed foot or ankle infections were included. All infections were confirmed microbiologically with positive intra-operative culture results. 7 (28%) patients with osteomyelitis (OM) of the foot, 11 (44%) with OM of the ankle, 5 (20%) with ankle septic arthritis and 2 (8%) patients with post-surgical wound infection were identified. Previous bony surgery was identified in 13 (52%) patients, either a corrective osteotomy or an open reduction and internal fixation for a foot or ankle fracture with the infection developing on top of the existing metalwork. 21 (84%) patients did have raised inflammatory markers while 4 (16%) patients failed to mount an inflammatory response even with subsequent debridement and removal of metal work. CRP sensitivity was 84%, while WCC sensitivity was only 28%.

CONCLUSION

CRP has a relatively good sensitivity in the diagnosis of foot and ankle infections in non-diabetic patients, whereas WCC is a poor inflammatory marker in the detection of such cases. In presence of clinically high level of suspicion of foot or ankle infection, a normal CRP should not rule out the diagnosis of OM.

Use of Novel Strategies to Develop Guidelines for Management of Pyogenic Osteomyelitis in Adults: A WikiGuidelines Group Consensus Statement

IMPORTANCE

Traditional approaches to practice guidelines frequently result in dissociation between strength of recommendation and quality of evidence.

OBJECTIVE

To construct a clinical guideline for pyogenic osteomyelitis management, with a new standard of evidence to resolve the gap between strength of recommendation and quality of evidence, through the use of a novel open access approach utilizing social media tools.

EVIDENCE REVIEW

This consensus statement and systematic review study used a novel approach from the WikiGuidelines Group, an open access collaborative research project, to construct clinical guidelines for pyogenic osteomyelitis. In June 2021 and February 2022, authors recruited via social media conducted multiple PubMed literature searches, including all years and languages, regarding osteomyelitis management; criteria for article quality and inclusion were specified in the group's charter. The GRADE system for evaluating evidence was not used based on previously published concerns regarding the potential dissociation between strength of recommendation and quality of evidence. Instead, the charter required that clear recommendations be made only when reproducible, prospective, controlled studies provided hypothesis-confirming evidence. In the absence of such data, clinical reviews were drafted to discuss pros and cons of care choices. Both clear recommendations and clinical reviews were planned with the intention to be regularly updated as new data become available.

FINDINGS

Sixty-three participants with diverse expertise from 8 countries developed the group's charter and its first guideline on pyogenic osteomyelitis. These participants included both nonacademic and academic physicians and pharmacists specializing in general internal medicine or hospital medicine, infectious diseases, orthopedic surgery, pharmacology, and medical microbiology. Of the 7 questions addressed in the guideline, 2 clear recommendations were offered for the use of oral antibiotic therapy and the duration of therapy. In addition, 5 clinical reviews were authored addressing diagnosis, approaches to osteomyelitis underlying a pressure ulcer, timing for the administration of empirical therapy, specific antimicrobial options (including empirical regimens, use of antimicrobials targeting resistant pathogens, the role of bone penetration, and the use of rifampin as adjunctive therapy), and the role of biomarkers and imaging to assess responses to therapy.

CONCLUSIONS AND RELEVANCE

The WikiGuidelines approach offers a novel methodology for clinical guideline development that precludes recommendations based on low-quality data or opinion. The primary limitation is the need for more rigorous clinical investigations, enabling additional clear recommendations for clinical questions currently unresolved by high-quality data.

Effect of Sensory Neuropathy on the Predictive Value of Inflammatory Biomarkers for Osteomyelitis in Diabetic and Nondiabetic Patients with Foot Infections

OBJECTIVE

To investigate the predictive value of erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP) in persons with and without diabetes with osteomyelitis (OM).

METHODS

We evaluated 455 patients in a retrospective cohort study of patients admitted to the hospital with diabetic foot OM (n = 177), diabetic foot soft-tissue infections (STIs) (n = 176), nondiabetic OM (n = 51), and nondiabetic STIs (n = 51). Infection diagnosis was determined through bone culture, histopathologic examination for OM, and/or imaging (magnetic resonance imaging/single-photon emission computed tomography) for STI. The optimal cutoff values of ESR and CRP in predicting OM were determined by receiver operating characteristic curve analysis. Sensitivity, specificity, positive and negative predictive values, and positive and negative likelihood ratios were determined through contingency tables.

RESULTS

In persons without diabetes with STI or OM, the mean ESR and CRP differences were 10.0 mm/h and 2.6 mg/dL, respectively. In contrast, persons with diabetes had higher levels of each: 24.8 mm/h and 6.8 mg/dL, respectively. As a result, ESR and CRP predicted OM better in patients with diabetes. However, when patients were stratified by neuropathy status, ESR remained predictive of OM in diabetic patients with neuropathy (75% sensitivity, 58% specificity) but not in diabetic patients without neuropathy (50% sensitivity, 44% specificity). Also, CRP remained predictive irrespective of neuropathy status. A similar trend was observed in patients without diabetes.

CONCLUSIONS

Previous studies have reported that ESR and CRP are predictive of OM. However, this study suggests that neuropathy influences the predictive value of inflammatory biomarkers. The underlying mechanisms require further study.

Erythrocyte Sedimentation Rate and C-Reactive Protein in Acute Inflammation

OBJECTIVES

To assess the diagnostic accuracy of erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP) in acute inflammation.

METHODS

PubMed and Scopus were searched and eligible articles were screened for methodologic quality using the Quality Assessment of the Diagnostic Accuracy Studies-Revised. Meta-analysis with calculation of pooled sensitivity (Se), specificity (Sp), and summary area under the curve (SAUC) was performed.

RESULTS

Twenty-nine studies were eligible. Se and Sp were 0.78 and 0.68 (SAUC = 0.80) for ESR in orthopedic infections and 0.79 and 0.70 (SAUC = 0.81) for CRP. For the diagnosis of other various inflammatory conditions, CRP had a superior diagnostic accuracy, with a Se of 0.86, Sp of 0.67, and SAUC of 0.86 compared with a Se of 0.77, Sp of 0.59, and SAUC of 0.75 for ESR. Heterogeneity among studies was elevated. Combined use of ESR and CRP yielded higher diagnostic accuracy.

CONCLUSIONS

Despite observed heterogeneity among studies, ESR and CRP have a similar diagnostic accuracy in assessment of inflammation, especially in orthopedic conditions.

What are the Optimal Cutoff Values for ESR and CRP to Diagnose Osteomyelitis in Patients with Diabetes-related Foot Infections?

BACKGROUND

Distinguishing osteomyelitis from soft-tissue infection of the foot is important because osteomyelitis is associated with more operations, amputation, and prolonged antibiotic exposure. Both erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP) are routinely ordered inflammatory biomarkers for evaluating foot infection. When initial evaluation is inconclusive, advanced imaging is indicated, and high clinical or radiographic suspicion of osteomyelitis may indicate bone biopsy to identify organisms and antibiotic sensitivity. Although ESR and CRP levels are helpful for distinguishing osteomyelitis from soft-tissue infections in patients with diabetes-related foot infections, parameters regarding optimal cutoff values for those tests have not, to our knowledge, been defined.

QUESTIONS/PURPOSES

(1) What are the optimal cutoff values for ESR and CRP to differentiate osteomyelitis from soft-tissue infection in patients with diabetes-related foot infection? (2) Can a diagnostic algorithm be derived to guide interpretation of ESR and CRP to improve recognition of osteomyelitis in the setting of diabetic foot infection?

METHODS

The medical records of 1842 patients between 18 and 89 years of age treated at our institution between January 1, 2010 and February 6, 2017 for foot infection were reviewed. For inclusion, patients must have had a diagnosis of diabetes mellitus, moderate or severe infection, ESR and CRP values within 72 hours of admission, either advanced imaging (MRI or single-positron emission computed tomography/computed tomography [SPECT/CT]) or bone biopsy during admission and must not have had comorbidities that could affect ESR and CRP, such as autoimmune disorders. As such, 1489 patients were excluded, and 353 patients were included in the study. Osteomyelitis was diagnosed by positive bone culture or histopathology. Osteomyelitis was considered to be absent if there was a negative MRI or SPECT/CT result, or negative bone culture and histology findings if imaging was inconclusive. We identified 176 patients with osteomyelitis and 177 with soft-tissue infection. A blinded investigator performed the statistics. Optimal cutoffs of ESR and CRP were determined using receiver operative characteristic (ROC) analysis. A diagnostic algorithm was determined using epidemiologic principles of screening evaluations.

RESULTS

An ESR of 60 mm/h and a CRP level of 7.9 mg/dL were determined to be the optimal cutoff points for predicting osteomyelitis based on results of the ROC analysis. The ESR threshold of 60 mm/h demonstrated a sensitivity of 74% (95% confidence interval [CI], 67-80) and specificity of 56% (95% CI, 48-63) for osteomyelitis, whereas the CRP threshold of 7.9 mg/dL had a sensitivity of 49% (95% CI, 41-57) and specificity of 80% (95% CI, 74-86). If the ESR is < 30 mm/h, the likelihood of osteomyelitis is low. However, if ESR is > 60 mm/h and CRP level is > 7.9 mg/dL, the likelihood of osteomyelitis is high, and treatment of suspected osteomyelitis should be strongly considered.

CONCLUSIONS

While ESR is better for ruling out osteomyelitis initially, CRP helps distinguish osteomyelitis from soft-tissue infection in patients with high ESR values. Further prospective studies addressing the prognostic value of ESR and CRP are needed, and a more comprehensive diagnostic algorithm should be developed to include other diagnostic tests such as probe-to-bone and imaging.

LEVEL OF EVIDENCE

Level III, diagnostic study.